tests: Use errno value rather than a specific int
[vpp.git] / test / test_bfd.py
index b4f082a..0842fd7 100644 (file)
@@ -1,16 +1,50 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+""" BFD tests """
 
 from __future__ import division
-import unittest
-import hashlib
+
 import binascii
+from collections import namedtuple
+import hashlib
+import ipaddress
+import reprlib
 import time
-from random import randint
-from bfd import *
-from framework import *
+import unittest
+from random import randint, shuffle, getrandbits
+from socket import AF_INET, AF_INET6
+
+import scapy.compat
+from scapy.layers.inet import UDP, IP
+from scapy.layers.inet6 import IPv6
+from scapy.layers.l2 import Ether, GRE
+from scapy.packet import Raw
+
+from config import config
+from bfd import (
+    VppBFDAuthKey,
+    BFD,
+    BFDAuthType,
+    VppBFDUDPSession,
+    BFDDiagCode,
+    BFDState,
+    BFD_vpp_echo,
+)
+from framework import VppTestCase
+from asfframework import (
+    tag_fixme_vpp_workers,
+    tag_fixme_debian11,
+    tag_run_solo,
+    VppTestRunner,
+)
 from util import ppp
+from vpp_ip import DpoProto
+from vpp_ip_route import VppIpRoute, VppRoutePath
+from vpp_lo_interface import VppLoInterface
+from vpp_papi_provider import UnexpectedApiReturnValueError, CliFailedCommandError
+from vpp_pg_interface import CaptureTimeoutError, is_ipv6_misc
+from vpp_gre_interface import VppGreInterface
 
-us_in_sec = 1000000
+USEC_IN_SEC = 1000000
 
 
 class AuthKeyFactory(object):
@@ -20,22 +54,29 @@ class AuthKeyFactory(object):
         self._conf_key_ids = {}
 
     def create_random_key(self, test, auth_type=BFDAuthType.keyed_sha1):
+        """create a random key with unique conf key id"""
         conf_key_id = randint(0, 0xFFFFFFFF)
         while conf_key_id in self._conf_key_ids:
             conf_key_id = randint(0, 0xFFFFFFFF)
         self._conf_key_ids[conf_key_id] = 1
-        key = str(bytearray([randint(0, 255) for j in range(randint(1, 20))]))
-        return VppBFDAuthKey(test=test, auth_type=auth_type,
-                             conf_key_id=conf_key_id, key=key)
+        key = scapy.compat.raw(
+            bytearray([randint(0, 255) for _ in range(randint(1, 20))])
+        )
+        return VppBFDAuthKey(
+            test=test, auth_type=auth_type, conf_key_id=conf_key_id, key=key
+        )
 
 
 class BFDAPITestCase(VppTestCase):
     """Bidirectional Forwarding Detection (BFD) - API"""
 
+    pg0 = None
+    pg1 = None
+
     @classmethod
     def setUpClass(cls):
         super(BFDAPITestCase, cls).setUpClass()
-
+        cls.vapi.cli("set log class bfd level debug")
         try:
             cls.create_pg_interfaces(range(2))
             for i in cls.pg_interfaces:
@@ -47,73 +88,115 @@ class BFDAPITestCase(VppTestCase):
             super(BFDAPITestCase, cls).tearDownClass()
             raise
 
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDAPITestCase, cls).tearDownClass()
+
     def setUp(self):
         super(BFDAPITestCase, self).setUp()
         self.factory = AuthKeyFactory()
 
     def test_add_bfd(self):
-        """ create a BFD session """
+        """create a BFD session"""
         session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
         session.add_vpp_config()
-        self.logger.debug("Session state is %s" % str(session.state))
+        self.logger.debug("Session state is %s", session.state)
         session.remove_vpp_config()
         session.add_vpp_config()
-        self.logger.debug("Session state is %s" % str(session.state))
+        self.logger.debug("Session state is %s", session.state)
         session.remove_vpp_config()
 
     def test_double_add(self):
-        """ create the same BFD session twice (negative case) """
+        """create the same BFD session twice (negative case)"""
         session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
         session.add_vpp_config()
 
-        with self.vapi.expect_negative_api_retval():
+        with self.vapi.assert_negative_api_retval():
             session.add_vpp_config()
 
         session.remove_vpp_config()
 
     def test_add_bfd6(self):
-        """ create IPv6 BFD session """
-        session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6)
+        """create IPv6 BFD session"""
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip6, af=AF_INET6)
         session.add_vpp_config()
-        self.logger.debug("Session state is %s" % str(session.state))
+        self.logger.debug("Session state is %s", session.state)
         session.remove_vpp_config()
         session.add_vpp_config()
-        self.logger.debug("Session state is %s" % str(session.state))
+        self.logger.debug("Session state is %s", session.state)
         session.remove_vpp_config()
 
     def test_mod_bfd(self):
-        """ modify BFD session parameters """
-        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
-                                   desired_min_tx=50000,
-                                   required_min_rx=10000,
-                                   detect_mult=1)
+        """modify BFD session parameters"""
+        session = VppBFDUDPSession(
+            self,
+            self.pg0,
+            self.pg0.remote_ip4,
+            desired_min_tx=50000,
+            required_min_rx=10000,
+            detect_mult=1,
+        )
         session.add_vpp_config()
-        e = session.get_bfd_udp_session_dump_entry()
-        self.assert_equal(session.desired_min_tx,
-                          e.desired_min_tx,
-                          "desired min transmit interval")
-        self.assert_equal(session.required_min_rx,
-                          e.required_min_rx,
-                          "required min receive interval")
-        self.assert_equal(session.detect_mult, e.detect_mult, "detect mult")
-        session.modify_parameters(desired_min_tx=session.desired_min_tx * 2,
-                                  required_min_rx=session.required_min_rx * 2,
-                                  detect_mult=session.detect_mult * 2)
-        e = session.get_bfd_udp_session_dump_entry()
-        self.assert_equal(session.desired_min_tx,
-                          e.desired_min_tx,
-                          "desired min transmit interval")
-        self.assert_equal(session.required_min_rx,
-                          e.required_min_rx,
-                          "required min receive interval")
-        self.assert_equal(session.detect_mult, e.detect_mult, "detect mult")
+        s = session.get_bfd_udp_session_dump_entry()
+        self.assert_equal(
+            session.desired_min_tx, s.desired_min_tx, "desired min transmit interval"
+        )
+        self.assert_equal(
+            session.required_min_rx, s.required_min_rx, "required min receive interval"
+        )
+        self.assert_equal(session.detect_mult, s.detect_mult, "detect mult")
+        session.modify_parameters(
+            desired_min_tx=session.desired_min_tx * 2,
+            required_min_rx=session.required_min_rx * 2,
+            detect_mult=session.detect_mult * 2,
+        )
+        s = session.get_bfd_udp_session_dump_entry()
+        self.assert_equal(
+            session.desired_min_tx, s.desired_min_tx, "desired min transmit interval"
+        )
+        self.assert_equal(
+            session.required_min_rx, s.required_min_rx, "required min receive interval"
+        )
+        self.assert_equal(session.detect_mult, s.detect_mult, "detect mult")
+
+    def test_upd_bfd(self):
+        """Create/Modify w/ Update BFD session parameters"""
+        session = VppBFDUDPSession(
+            self,
+            self.pg0,
+            self.pg0.remote_ip4,
+            desired_min_tx=50000,
+            required_min_rx=10000,
+            detect_mult=1,
+        )
+        session.upd_vpp_config()
+        s = session.get_bfd_udp_session_dump_entry()
+        self.assert_equal(
+            session.desired_min_tx, s.desired_min_tx, "desired min transmit interval"
+        )
+        self.assert_equal(
+            session.required_min_rx, s.required_min_rx, "required min receive interval"
+        )
+
+        self.assert_equal(session.detect_mult, s.detect_mult, "detect mult")
+        session.upd_vpp_config(
+            desired_min_tx=session.desired_min_tx * 2,
+            required_min_rx=session.required_min_rx * 2,
+            detect_mult=session.detect_mult * 2,
+        )
+        s = session.get_bfd_udp_session_dump_entry()
+        self.assert_equal(
+            session.desired_min_tx, s.desired_min_tx, "desired min transmit interval"
+        )
+        self.assert_equal(
+            session.required_min_rx, s.required_min_rx, "required min receive interval"
+        )
+        self.assert_equal(session.detect_mult, s.detect_mult, "detect mult")
 
     def test_add_sha1_keys(self):
-        """ add SHA1 keys """
+        """add SHA1 keys"""
         key_count = 10
-        keys = [self.factory.create_random_key(
-            self) for i in range(0, key_count)]
+        keys = [self.factory.create_random_key(self) for i in range(0, key_count)]
         for key in keys:
             self.assertFalse(key.query_vpp_config())
         for key in keys:
@@ -121,8 +204,8 @@ class BFDAPITestCase(VppTestCase):
         for key in keys:
             self.assertTrue(key.query_vpp_config())
         # remove randomly
-        indexes = range(key_count)
-        random.shuffle(indexes)
+        indexes = list(range(key_count))
+        shuffle(indexes)
         removed = []
         for i in indexes:
             key = keys[i]
@@ -148,64 +231,68 @@ class BFDAPITestCase(VppTestCase):
             self.assertFalse(key.query_vpp_config())
 
     def test_add_bfd_sha1(self):
-        """ create a BFD session (SHA1) """
+        """create a BFD session (SHA1)"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
-                                   sha1_key=key)
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
         session.add_vpp_config()
-        self.logger.debug("Session state is %s" % str(session.state))
+        self.logger.debug("Session state is %s", session.state)
         session.remove_vpp_config()
         session.add_vpp_config()
-        self.logger.debug("Session state is %s" % str(session.state))
+        self.logger.debug("Session state is %s", session.state)
         session.remove_vpp_config()
 
     def test_double_add_sha1(self):
-        """ create the same BFD session twice (negative case) (SHA1) """
+        """create the same BFD session twice (negative case) (SHA1)"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
-                                   sha1_key=key)
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
         session.add_vpp_config()
         with self.assertRaises(Exception):
             session.add_vpp_config()
 
-    def test_add_authenticated_with_nonexistent_key(self):
-        """ create BFD session using non-existent SHA1 (negative case) """
+    def test_add_auth_nonexistent_key(self):
+        """create BFD session using non-existent SHA1 (negative case)"""
         session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip4,
-            sha1_key=self.factory.create_random_key(self))
+            self,
+            self.pg0,
+            self.pg0.remote_ip4,
+            sha1_key=self.factory.create_random_key(self),
+        )
         with self.assertRaises(Exception):
             session.add_vpp_config()
 
     def test_shared_sha1_key(self):
-        """ share single SHA1 key between multiple BFD sessions """
+        """single SHA1 key shared by multiple BFD sessions"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
         sessions = [
-            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
-                             sha1_key=key),
-            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip6,
-                             sha1_key=key, af=AF_INET6),
-            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip4,
-                             sha1_key=key),
-            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip6,
-                             sha1_key=key, af=AF_INET6)]
+            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4, sha1_key=key),
+            VppBFDUDPSession(
+                self, self.pg0, self.pg0.remote_ip6, sha1_key=key, af=AF_INET6
+            ),
+            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip4, sha1_key=key),
+            VppBFDUDPSession(
+                self, self.pg1, self.pg1.remote_ip6, sha1_key=key, af=AF_INET6
+            ),
+        ]
         for s in sessions:
             s.add_vpp_config()
         removed = 0
         for s in sessions:
             e = key.get_bfd_auth_keys_dump_entry()
-            self.assert_equal(e.use_count, len(sessions) - removed,
-                              "Use count for shared key")
+            self.assert_equal(
+                e.use_count, len(sessions) - removed, "Use count for shared key"
+            )
             s.remove_vpp_config()
             removed += 1
         e = key.get_bfd_auth_keys_dump_entry()
-        self.assert_equal(e.use_count, len(sessions) - removed,
-                          "Use count for shared key")
+        self.assert_equal(
+            e.use_count, len(sessions) - removed, "Use count for shared key"
+        )
 
     def test_activate_auth(self):
-        """ activate SHA1 authentication """
+        """activate SHA1 authentication"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
         session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
@@ -213,7 +300,7 @@ class BFDAPITestCase(VppTestCase):
         session.activate_auth(key)
 
     def test_deactivate_auth(self):
-        """ deactivate SHA1 authentication """
+        """deactivate SHA1 authentication"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
         session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
@@ -222,49 +309,195 @@ class BFDAPITestCase(VppTestCase):
         session.deactivate_auth()
 
     def test_change_key(self):
-        """ change SHA1 key """
+        """change SHA1 key"""
         key1 = self.factory.create_random_key(self)
         key2 = self.factory.create_random_key(self)
         while key2.conf_key_id == key1.conf_key_id:
             key2 = self.factory.create_random_key(self)
         key1.add_vpp_config()
         key2.add_vpp_config()
-        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
-                                   sha1_key=key1)
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4, sha1_key=key1)
         session.add_vpp_config()
         session.activate_auth(key2)
 
+    def test_set_del_udp_echo_source(self):
+        """set/del udp echo source"""
+        self.create_loopback_interfaces(1)
+        self.loopback0 = self.lo_interfaces[0]
+        self.loopback0.admin_up()
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertFalse(echo_source.is_set)
+        self.assertFalse(echo_source.have_usable_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertTrue(echo_source.is_set)
+        self.assertEqual(echo_source.sw_if_index, self.loopback0.sw_if_index)
+        self.assertFalse(echo_source.have_usable_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+        self.loopback0.config_ip4()
+        echo_ip4 = ipaddress.IPv4Address(
+            int(ipaddress.IPv4Address(self.loopback0.local_ip4)) ^ 1
+        ).packed
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertTrue(echo_source.is_set)
+        self.assertEqual(echo_source.sw_if_index, self.loopback0.sw_if_index)
+        self.assertTrue(echo_source.have_usable_ip4)
+        self.assertEqual(echo_source.ip4_addr.packed, echo_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+        self.loopback0.config_ip6()
+        echo_ip6 = ipaddress.IPv6Address(
+            int(ipaddress.IPv6Address(self.loopback0.local_ip6)) ^ 1
+        ).packed
+
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertTrue(echo_source.is_set)
+        self.assertEqual(echo_source.sw_if_index, self.loopback0.sw_if_index)
+        self.assertTrue(echo_source.have_usable_ip4)
+        self.assertEqual(echo_source.ip4_addr.packed, echo_ip4)
+        self.assertTrue(echo_source.have_usable_ip6)
+        self.assertEqual(echo_source.ip6_addr.packed, echo_ip6)
+
+        self.vapi.bfd_udp_del_echo_source()
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertFalse(echo_source.is_set)
+        self.assertFalse(echo_source.have_usable_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
 
-class BFDTestSession(object):
-    """ BFD session as seen from test framework side """
 
-    def __init__(self, test, interface, af, detect_mult=3, sha1_key=None,
-                 bfd_key_id=None, our_seq_number=0xFFFFFFFF - 4):
+class BFDTestSession(object):
+    """BFD session as seen from test framework side"""
+
+    def __init__(
+        self,
+        test,
+        interface,
+        af,
+        detect_mult=3,
+        sha1_key=None,
+        bfd_key_id=None,
+        our_seq_number=None,
+        tunnel_header=None,
+        phy_interface=None,
+    ):
         self.test = test
         self.af = af
         self.sha1_key = sha1_key
         self.bfd_key_id = bfd_key_id
         self.interface = interface
-        self.udp_sport = 50000
-        self.our_seq_number = our_seq_number
+        if phy_interface:
+            self.phy_interface = phy_interface
+        else:
+            self.phy_interface = self.interface
+        self.udp_sport = randint(49152, 65535)
+        if our_seq_number is None:
+            self.our_seq_number = randint(0, 40000000)
+        else:
+            self.our_seq_number = our_seq_number
         self.vpp_seq_number = None
-        self.bfd_values = {
-            'my_discriminator': 0,
-            'desired_min_tx_interval': 100000,
-            'detect_mult': detect_mult,
-            'diag': BFDDiagCode.no_diagnostic,
-        }
+        self.my_discriminator = 0
+        self.desired_min_tx = 300000
+        self.required_min_rx = 300000
+        self.required_min_echo_rx = None
+        self.detect_mult = detect_mult
+        self.diag = BFDDiagCode.no_diagnostic
+        self.your_discriminator = None
+        self.state = BFDState.down
+        self.auth_type = BFDAuthType.no_auth
+        self.tunnel_header = tunnel_header
+        self.tx_packets = 0
+        self.rx_packets = 0
+        self.tx_packets_echo = 0
+        self.rx_packets_echo = 0
 
     def inc_seq_num(self):
+        """increment sequence number, wrapping if needed"""
         if self.our_seq_number == 0xFFFFFFFF:
             self.our_seq_number = 0
         else:
             self.our_seq_number += 1
 
-    def update(self, **kwargs):
-        self.bfd_values.update(kwargs)
+    def update(
+        self,
+        my_discriminator=None,
+        your_discriminator=None,
+        desired_min_tx=None,
+        required_min_rx=None,
+        required_min_echo_rx=None,
+        detect_mult=None,
+        diag=None,
+        state=None,
+        auth_type=None,
+    ):
+        """update BFD parameters associated with session"""
+        if my_discriminator is not None:
+            self.my_discriminator = my_discriminator
+        if your_discriminator is not None:
+            self.your_discriminator = your_discriminator
+        if required_min_rx is not None:
+            self.required_min_rx = required_min_rx
+        if required_min_echo_rx is not None:
+            self.required_min_echo_rx = required_min_echo_rx
+        if desired_min_tx is not None:
+            self.desired_min_tx = desired_min_tx
+        if detect_mult is not None:
+            self.detect_mult = detect_mult
+        if diag is not None:
+            self.diag = diag
+        if state is not None:
+            self.state = state
+        if auth_type is not None:
+            self.auth_type = auth_type
+
+    def fill_packet_fields(self, packet):
+        """set packet fields with known values in packet"""
+        bfd = packet[BFD]
+        if self.my_discriminator:
+            self.test.logger.debug(
+                "BFD: setting packet.my_discriminator=%s", self.my_discriminator
+            )
+            bfd.my_discriminator = self.my_discriminator
+        if self.your_discriminator:
+            self.test.logger.debug(
+                "BFD: setting packet.your_discriminator=%s", self.your_discriminator
+            )
+            bfd.your_discriminator = self.your_discriminator
+        if self.required_min_rx:
+            self.test.logger.debug(
+                "BFD: setting packet.required_min_rx_interval=%s", self.required_min_rx
+            )
+            bfd.required_min_rx_interval = self.required_min_rx
+        if self.required_min_echo_rx:
+            self.test.logger.debug(
+                "BFD: setting packet.required_min_echo_rx=%s", self.required_min_echo_rx
+            )
+            bfd.required_min_echo_rx_interval = self.required_min_echo_rx
+        if self.desired_min_tx:
+            self.test.logger.debug(
+                "BFD: setting packet.desired_min_tx_interval=%s", self.desired_min_tx
+            )
+            bfd.desired_min_tx_interval = self.desired_min_tx
+        if self.detect_mult:
+            self.test.logger.debug(
+                "BFD: setting packet.detect_mult=%s", self.detect_mult
+            )
+            bfd.detect_mult = self.detect_mult
+        if self.diag:
+            self.test.logger.debug("BFD: setting packet.diag=%s", self.diag)
+            bfd.diag = self.diag
+        if self.state:
+            self.test.logger.debug("BFD: setting packet.state=%s", self.state)
+            bfd.state = self.state
+        if self.auth_type:
+            # this is used by a negative test-case
+            self.test.logger.debug("BFD: setting packet.auth_type=%s", self.auth_type)
+            bfd.auth_type = self.auth_type
 
     def create_packet(self):
+        """create a BFD packet, reflecting the current state of session"""
         if self.sha1_key:
             bfd = BFD(flags="A")
             bfd.auth_type = self.sha1_key.auth_type
@@ -274,209 +507,338 @@ class BFDTestSession(object):
             bfd.length = BFD.sha1_auth_len + BFD.bfd_pkt_len
         else:
             bfd = BFD()
+        packet = Ether(
+            src=self.phy_interface.remote_mac, dst=self.phy_interface.local_mac
+        )
+        if self.tunnel_header:
+            packet = packet / self.tunnel_header
         if self.af == AF_INET6:
-            packet = (Ether(src=self.interface.remote_mac,
-                            dst=self.interface.local_mac) /
-                      IPv6(src=self.interface.remote_ip6,
-                           dst=self.interface.local_ip6,
-                           hlim=255) /
-                      UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
-                      bfd)
+            packet = (
+                packet
+                / IPv6(
+                    src=self.interface.remote_ip6,
+                    dst=self.interface.local_ip6,
+                    hlim=255,
+                )
+                / UDP(sport=self.udp_sport, dport=BFD.udp_dport)
+                / bfd
+            )
         else:
-            packet = (Ether(src=self.interface.remote_mac,
-                            dst=self.interface.local_mac) /
-                      IP(src=self.interface.remote_ip4,
-                         dst=self.interface.local_ip4,
-                         ttl=255) /
-                      UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
-                      bfd)
+            packet = (
+                packet
+                / IP(
+                    src=self.interface.remote_ip4, dst=self.interface.local_ip4, ttl=255
+                )
+                / UDP(sport=self.udp_sport, dport=BFD.udp_dport)
+                / bfd
+            )
         self.test.logger.debug("BFD: Creating packet")
-        for name, value in self.bfd_values.iteritems():
-            self.test.logger.debug("BFD: setting packet.%s=%s", name, value)
-            packet[BFD].setfieldval(name, value)
+        self.fill_packet_fields(packet)
         if self.sha1_key:
-            hash_material = str(packet[BFD])[:32] + self.sha1_key.key + \
-                "\0" * (20 - len(self.sha1_key.key))
-            self.test.logger.debug("BFD: Calculated SHA1 hash: %s" %
-                                   hashlib.sha1(hash_material).hexdigest())
+            hash_material = (
+                scapy.compat.raw(packet[BFD])[:32]
+                + self.sha1_key.key
+                + b"\0" * (20 - len(self.sha1_key.key))
+            )
+            self.test.logger.debug(
+                "BFD: Calculated SHA1 hash: %s"
+                % hashlib.sha1(hash_material).hexdigest()
+            )
             packet[BFD].auth_key_hash = hashlib.sha1(hash_material).digest()
         return packet
 
-    def send_packet(self, packet=None):
+    def send_packet(self, packet=None, interface=None):
+        """send packet on interface, creating the packet if needed"""
         if packet is None:
             packet = self.create_packet()
+        if interface is None:
+            interface = self.phy_interface
         self.test.logger.debug(ppp("Sending packet:", packet))
-        self.test.pg0.add_stream([packet])
+        interface.add_stream(packet)
+        self.tx_packets += 1
         self.test.pg_start()
 
     def verify_sha1_auth(self, packet):
-        """ Verify correctness of authentication in BFD layer. """
+        """Verify correctness of authentication in BFD layer."""
         bfd = packet[BFD]
         self.test.assert_equal(bfd.auth_len, 28, "Auth section length")
-        self.test.assert_equal(bfd.auth_type, self.sha1_key.auth_type,
-                               BFDAuthType)
+        self.test.assert_equal(bfd.auth_type, self.sha1_key.auth_type, BFDAuthType)
         self.test.assert_equal(bfd.auth_key_id, self.bfd_key_id, "Key ID")
         self.test.assert_equal(bfd.auth_reserved, 0, "Reserved")
         if self.vpp_seq_number is None:
             self.vpp_seq_number = bfd.auth_seq_num
-            self.test.logger.debug("Received initial sequence number: %s" %
-                                   self.vpp_seq_number)
+            self.test.logger.debug(
+                "Received initial sequence number: %s" % self.vpp_seq_number
+            )
         else:
             recvd_seq_num = bfd.auth_seq_num
-            self.test.logger.debug("Received followup sequence number: %s" %
-                                   recvd_seq_num)
-            if self.vpp_seq_number < 0xffffffff:
-                if self.sha1_key.auth_type == \
-                        BFDAuthType.meticulous_keyed_sha1:
-                    self.test.assert_equal(recvd_seq_num,
-                                           self.vpp_seq_number + 1,
-                                           "BFD sequence number")
+            self.test.logger.debug(
+                "Received followup sequence number: %s" % recvd_seq_num
+            )
+            if self.vpp_seq_number < 0xFFFFFFFF:
+                if self.sha1_key.auth_type == BFDAuthType.meticulous_keyed_sha1:
+                    self.test.assert_equal(
+                        recvd_seq_num, self.vpp_seq_number + 1, "BFD sequence number"
+                    )
                 else:
-                    self.test.assert_in_range(recvd_seq_num,
-                                              self.vpp_seq_number,
-                                              self.vpp_seq_number + 1,
-                                              "BFD sequence number")
+                    self.test.assert_in_range(
+                        recvd_seq_num,
+                        self.vpp_seq_number,
+                        self.vpp_seq_number + 1,
+                        "BFD sequence number",
+                    )
             else:
-                if self.sha1_key.auth_type == \
-                        BFDAuthType.meticulous_keyed_sha1:
-                    self.test.assert_equal(recvd_seq_num, 0,
-                                           "BFD sequence number")
+                if self.sha1_key.auth_type == BFDAuthType.meticulous_keyed_sha1:
+                    self.test.assert_equal(recvd_seq_num, 0, "BFD sequence number")
                 else:
-                    self.test.assertIn(recvd_seq_num, (self.vpp_seq_number, 0),
-                                       "BFD sequence number not one of "
-                                       "(%s, 0)" % self.vpp_seq_number)
+                    self.test.assertIn(
+                        recvd_seq_num,
+                        (self.vpp_seq_number, 0),
+                        "BFD sequence number not one of "
+                        "(%s, 0)" % self.vpp_seq_number,
+                    )
             self.vpp_seq_number = recvd_seq_num
         # last 20 bytes represent the hash - so replace them with the key,
         # pad the result with zeros and hash the result
-        hash_material = bfd.original[:-20] + self.sha1_key.key + \
-            "\0" * (20 - len(self.sha1_key.key))
+        hash_material = (
+            bfd.original[:-20]
+            + self.sha1_key.key
+            + b"\0" * (20 - len(self.sha1_key.key))
+        )
         expected_hash = hashlib.sha1(hash_material).hexdigest()
-        self.test.assert_equal(binascii.hexlify(bfd.auth_key_hash),
-                               expected_hash, "Auth key hash")
+        self.test.assert_equal(
+            binascii.hexlify(bfd.auth_key_hash), expected_hash.encode(), "Auth key hash"
+        )
 
     def verify_bfd(self, packet):
-        """ Verify correctness of BFD layer. """
+        """Verify correctness of BFD layer."""
         bfd = packet[BFD]
         self.test.assert_equal(bfd.version, 1, "BFD version")
-        self.test.assert_equal(bfd.your_discriminator,
-                               self.bfd_values['my_discriminator'],
-                               "BFD - your discriminator")
+        self.test.assert_equal(
+            bfd.your_discriminator, self.my_discriminator, "BFD - your discriminator"
+        )
         if self.sha1_key:
             self.verify_sha1_auth(packet)
 
 
-class BFDCommonCode:
-    """Common code used by both IPv4 and IPv6 Test Cases"""
-
-    def tearDown(self):
-        self.vapi.collect_events()  # clear the event queue
-        if not self.vpp_dead:
-            self.vapi.want_bfd_events(enable_disable=0)
-
-    def bfd_session_up(self):
-        """ Bring BFD session up """
-        self.logger.info("BFD: Waiting for slow hello")
-        p, timeout = self.wait_for_bfd_packet(2)
-        self.logger.info("BFD: Sending Init")
-        self.test_session.update(my_discriminator=randint(0, 40000000),
-                                 your_discriminator=p[BFD].my_discriminator,
-                                 state=BFDState.init,
-                                 required_min_rx_interval=100000)
-        self.test_session.send_packet()
-        self.logger.info("BFD: Waiting for event")
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
-        self.verify_event(e, expected_state=BFDState.up)
-        self.logger.info("BFD: Session is Up")
-        self.test_session.update(state=BFDState.up)
-        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-
-    def bfd_session_down(self):
-        """ Bring BFD session down """
-        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.test_session.update(state=BFDState.down)
-        self.test_session.send_packet()
-        self.logger.info("BFD: Waiting for event")
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
-        self.verify_event(e, expected_state=BFDState.down)
-        self.logger.info("BFD: Session is Down")
-        self.assert_equal(self.vpp_session.state, BFDState.down, BFDState)
-
-    def verify_ip(self, packet):
-        """ Verify correctness of IP layer. """
-        if self.vpp_session.af == AF_INET6:
-            ip = packet[IPv6]
-            local_ip = self.pg0.local_ip6
-            remote_ip = self.pg0.remote_ip6
-            self.assert_equal(ip.hlim, 255, "IPv6 hop limit")
-        else:
-            ip = packet[IP]
-            local_ip = self.pg0.local_ip4
-            remote_ip = self.pg0.remote_ip4
-            self.assert_equal(ip.ttl, 255, "IPv4 TTL")
-        self.assert_equal(ip.src, local_ip, "IP source address")
-        self.assert_equal(ip.dst, remote_ip, "IP destination address")
-
-    def verify_udp(self, packet):
-        """ Verify correctness of UDP layer. """
-        udp = packet[UDP]
-        self.assert_equal(udp.dport, BFD.udp_dport, "UDP destination port")
-        self.assert_in_range(udp.sport, BFD.udp_sport_min, BFD.udp_sport_max,
-                             "UDP source port")
-
-    def verify_event(self, event, expected_state):
-        """ Verify correctness of event values. """
-        e = event
-        self.logger.debug("BFD: Event: %s" % repr(e))
-        self.assert_equal(e.sw_if_index,
-                          self.vpp_session.interface.sw_if_index,
-                          "BFD interface index")
-        is_ipv6 = 0
-        if self.vpp_session.af == AF_INET6:
-            is_ipv6 = 1
-        self.assert_equal(e.is_ipv6, is_ipv6, "is_ipv6")
-        if self.vpp_session.af == AF_INET:
-            self.assert_equal(e.local_addr[:4], self.vpp_session.local_addr_n,
-                              "Local IPv4 address")
-            self.assert_equal(e.peer_addr[:4], self.vpp_session.peer_addr_n,
-                              "Peer IPv4 address")
+def bfd_session_up(test):
+    """Bring BFD session up"""
+    test.logger.info("BFD: Waiting for slow hello")
+    p = wait_for_bfd_packet(test, 2, is_tunnel=test.vpp_session.is_tunnel)
+    old_offset = None
+    if hasattr(test, "vpp_clock_offset"):
+        old_offset = test.vpp_clock_offset
+    test.vpp_clock_offset = time.time() - float(p.time)
+    test.logger.debug("BFD: Calculated vpp clock offset: %s", test.vpp_clock_offset)
+    if old_offset:
+        test.assertAlmostEqual(
+            old_offset,
+            test.vpp_clock_offset,
+            delta=0.5,
+            msg="vpp clock offset not stable (new: %s, old: %s)"
+            % (test.vpp_clock_offset, old_offset),
+        )
+    test.logger.info("BFD: Sending Init")
+    test.test_session.update(
+        my_discriminator=randint(0, 40000000),
+        your_discriminator=p[BFD].my_discriminator,
+        state=BFDState.init,
+    )
+    if (
+        test.test_session.sha1_key
+        and test.test_session.sha1_key.auth_type == BFDAuthType.meticulous_keyed_sha1
+    ):
+        test.test_session.inc_seq_num()
+    test.test_session.send_packet()
+    test.logger.info("BFD: Waiting for event")
+    e = test.vapi.wait_for_event(1, "bfd_udp_session_event")
+    verify_event(test, e, expected_state=BFDState.up)
+    test.logger.info("BFD: Session is Up")
+    test.test_session.update(state=BFDState.up)
+    if (
+        test.test_session.sha1_key
+        and test.test_session.sha1_key.auth_type == BFDAuthType.meticulous_keyed_sha1
+    ):
+        test.test_session.inc_seq_num()
+    test.test_session.send_packet()
+    test.assert_equal(test.vpp_session.state, BFDState.up, BFDState)
+
+
+def bfd_session_down(test):
+    """Bring BFD session down"""
+    test.assert_equal(test.vpp_session.state, BFDState.up, BFDState)
+    test.test_session.update(state=BFDState.down)
+    if (
+        test.test_session.sha1_key
+        and test.test_session.sha1_key.auth_type == BFDAuthType.meticulous_keyed_sha1
+    ):
+        test.test_session.inc_seq_num()
+    test.test_session.send_packet()
+    test.logger.info("BFD: Waiting for event")
+    e = test.vapi.wait_for_event(1, "bfd_udp_session_event")
+    verify_event(test, e, expected_state=BFDState.down)
+    test.logger.info("BFD: Session is Down")
+    test.assert_equal(test.vpp_session.state, BFDState.down, BFDState)
+
+
+def verify_bfd_session_config(test, session, state=None):
+    dump = session.get_bfd_udp_session_dump_entry()
+    test.assertIsNotNone(dump)
+    # since dump is not none, we have verified that sw_if_index and addresses
+    # are valid (in get_bfd_udp_session_dump_entry)
+    if state:
+        test.assert_equal(dump.state, state, "session state")
+    test.assert_equal(
+        dump.required_min_rx, session.required_min_rx, "required min rx interval"
+    )
+    test.assert_equal(
+        dump.desired_min_tx, session.desired_min_tx, "desired min tx interval"
+    )
+    test.assert_equal(dump.detect_mult, session.detect_mult, "detect multiplier")
+    if session.sha1_key is None:
+        test.assert_equal(dump.is_authenticated, 0, "is_authenticated flag")
+    else:
+        test.assert_equal(dump.is_authenticated, 1, "is_authenticated flag")
+        test.assert_equal(dump.bfd_key_id, session.bfd_key_id, "bfd key id")
+        test.assert_equal(
+            dump.conf_key_id, session.sha1_key.conf_key_id, "config key id"
+        )
+
+
+def verify_ip(test, packet):
+    """Verify correctness of IP layer."""
+    if test.vpp_session.af == AF_INET6:
+        ip = packet[IPv6]
+        local_ip = test.vpp_session.interface.local_ip6
+        remote_ip = test.vpp_session.interface.remote_ip6
+        test.assert_equal(ip.hlim, 255, "IPv6 hop limit")
+    else:
+        ip = packet[IP]
+        local_ip = test.vpp_session.interface.local_ip4
+        remote_ip = test.vpp_session.interface.remote_ip4
+        test.assert_equal(ip.ttl, 255, "IPv4 TTL")
+    test.assert_equal(ip.src, local_ip, "IP source address")
+    test.assert_equal(ip.dst, remote_ip, "IP destination address")
+
+
+def verify_udp(test, packet):
+    """Verify correctness of UDP layer."""
+    udp = packet[UDP]
+    test.assert_equal(udp.dport, BFD.udp_dport, "UDP destination port")
+    test.assert_in_range(
+        udp.sport, BFD.udp_sport_min, BFD.udp_sport_max, "UDP source port"
+    )
+
+
+def verify_event(test, event, expected_state):
+    """Verify correctness of event values."""
+    e = event
+    test.logger.debug("BFD: Event: %s" % reprlib.repr(e))
+    test.assert_equal(
+        e.sw_if_index, test.vpp_session.interface.sw_if_index, "BFD interface index"
+    )
+
+    test.assert_equal(
+        str(e.local_addr), test.vpp_session.local_addr, "Local IPv6 address"
+    )
+    test.assert_equal(str(e.peer_addr), test.vpp_session.peer_addr, "Peer IPv6 address")
+    test.assert_equal(e.state, expected_state, BFDState)
+
+
+def wait_for_bfd_packet(test, timeout=1, pcap_time_min=None, is_tunnel=False):
+    """wait for BFD packet and verify its correctness
+
+    :param timeout: how long to wait
+    :param pcap_time_min: ignore packets with pcap timestamp lower than this
+
+    :returns: tuple (packet, time spent waiting for packet)
+    """
+    test.logger.info("BFD: Waiting for BFD packet")
+    deadline = time.time() + timeout
+    counter = 0
+    while True:
+        counter += 1
+        # sanity check
+        test.assert_in_range(counter, 0, 100, "number of packets ignored")
+        time_left = deadline - time.time()
+        if time_left < 0:
+            raise CaptureTimeoutError("Packet did not arrive within timeout")
+        p = test.pg0.wait_for_packet(timeout=time_left)
+        test.test_session.rx_packets += 1
+        test.logger.debug(ppp("BFD: Got packet:", p))
+        if pcap_time_min is not None and p.time < pcap_time_min:
+            test.logger.debug(
+                ppp(
+                    "BFD: ignoring packet (pcap time %s < "
+                    "pcap time min %s):" % (p.time, pcap_time_min),
+                    p,
+                )
+            )
         else:
-            self.assert_equal(e.local_addr, self.vpp_session.local_addr_n,
-                              "Local IPv6 address")
-            self.assert_equal(e.peer_addr, self.vpp_session.peer_addr_n,
-                              "Peer IPv6 address")
-        self.assert_equal(e.state, expected_state, BFDState)
-
-    def wait_for_bfd_packet(self, timeout=1):
-        """ wait for BFD packet
-
-        :param timeout: how long to wait max
-
-        :returns: tuple (packet, time spent waiting for packet)
-        """
-        self.logger.info("BFD: Waiting for BFD packet")
-        before = time.time()
-        p = self.pg0.wait_for_packet(timeout=timeout)
-        after = time.time()
-        self.logger.debug(ppp("BFD: Got packet:", p))
-        bfd = p[BFD]
-        if bfd is None:
-            raise Exception(ppp("Unexpected or invalid BFD packet:", p))
-        if bfd.payload:
-            raise Exception(ppp("Unexpected payload in BFD packet:", bfd))
-        self.verify_ip(p)
-        self.verify_udp(p)
-        self.test_session.verify_bfd(p)
-        return p, after - before
-
-
-class BFD4TestCase(VppTestCase, BFDCommonCode):
+            break
+    test.logger.debug(test.vapi.ppcli("show trace"))
+    if is_tunnel:
+        # strip an IP layer and move to the next
+        p = p[IP].payload
+
+    bfd = p[BFD]
+    if bfd is None:
+        raise Exception(ppp("Unexpected or invalid BFD packet:", p))
+    if bfd.payload:
+        raise Exception(ppp("Unexpected payload in BFD packet:", bfd))
+    verify_ip(test, p)
+    verify_udp(test, p)
+    test.test_session.verify_bfd(p)
+    return p
+
+
+BFDStats = namedtuple("BFDStats", "rx rx_echo tx tx_echo")
+
+
+def bfd_grab_stats_snapshot(test, bs_idx=0, thread_index=None):
+    s = test.statistics
+    ti = thread_index
+    if ti is None:
+        rx = s["/bfd/rx-session-counters"][:, bs_idx].sum_packets()
+        rx_echo = s["/bfd/rx-session-echo-counters"][:, bs_idx].sum_packets()
+        tx = s["/bfd/tx-session-counters"][:, bs_idx].sum_packets()
+        tx_echo = s["/bfd/tx-session-echo-counters"][:, bs_idx].sum_packets()
+    else:
+        rx = s["/bfd/rx-session-counters"][ti, bs_idx].sum_packets()
+        rx_echo = s["/bfd/rx-session-echo-counters"][ti, bs_idx].sum_packets()
+        tx = s["/bfd/tx-session-counters"][ti, bs_idx].sum_packets()
+        tx_echo = s["/bfd/tx-session-echo-counters"][ti, bs_idx].sum_packets()
+    return BFDStats(rx, rx_echo, tx, tx_echo)
+
+
+def bfd_stats_diff(stats_before, stats_after):
+    rx = stats_after.rx - stats_before.rx
+    rx_echo = stats_after.rx_echo - stats_before.rx_echo
+    tx = stats_after.tx - stats_before.tx
+    tx_echo = stats_after.tx_echo - stats_before.tx_echo
+    return BFDStats(rx, rx_echo, tx, tx_echo)
+
+
+@tag_run_solo
+@tag_fixme_debian11
+class BFD4TestCase(VppTestCase):
     """Bidirectional Forwarding Detection (BFD)"""
 
+    pg0 = None
+    vpp_clock_offset = None
+    vpp_session = None
+    test_session = None
+
     @classmethod
     def setUpClass(cls):
         super(BFD4TestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
         try:
             cls.create_pg_interfaces([0])
+            cls.create_loopback_interfaces(1)
+            cls.loopback0 = cls.lo_interfaces[0]
+            cls.loopback0.config_ip4()
+            cls.loopback0.admin_up()
             cls.pg0.config_ip4()
             cls.pg0.configure_ipv4_neighbors()
             cls.pg0.admin_up()
@@ -486,301 +848,1363 @@ class BFD4TestCase(VppTestCase, BFDCommonCode):
             super(BFD4TestCase, cls).tearDownClass()
             raise
 
+    @classmethod
+    def tearDownClass(cls):
+        super(BFD4TestCase, cls).tearDownClass()
+
     def setUp(self):
         super(BFD4TestCase, self).setUp()
         self.factory = AuthKeyFactory()
         self.vapi.want_bfd_events()
-        self.pg_enable_capture([self.pg0])
+        self.pg0.enable_capture()
         try:
-            self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                                self.pg0.remote_ip4)
+            self.bfd_udp4_sessions = self.statistics["/bfd/udp4/sessions"]
+            self.bfd_udp6_sessions = self.statistics["/bfd/udp6/sessions"]
+            self.vapi.cli("trace add bfd-process 500")
+            self.vpp_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
             self.vpp_session.add_vpp_config()
             self.vpp_session.admin_up()
             self.test_session = BFDTestSession(self, self.pg0, AF_INET)
-        except:
+        except BaseException:
             self.vapi.want_bfd_events(enable_disable=0)
             raise
 
     def tearDown(self):
-        BFDCommonCode.tearDown(self)
-        VppTestCase.tearDown(self)
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=0)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFD4TestCase, self).tearDown()
 
     def test_session_up(self):
-        """ bring BFD session up """
-        self.bfd_session_up()
+        """bring BFD session up"""
+        bfd_session_up(self)
+        bfd_udp4_sessions = self.statistics["/bfd/udp4/sessions"]
+        bfd_udp6_sessions = self.statistics["/bfd/udp6/sessions"]
+        self.assert_equal(bfd_udp4_sessions - self.bfd_udp4_sessions, 1)
+        self.assert_equal(bfd_udp6_sessions, self.bfd_udp6_sessions)
+
+    def test_session_up_by_ip(self):
+        """bring BFD session up - first frame looked up by address pair"""
+        self.logger.info("BFD: Sending Slow control frame")
+        self.test_session.update(my_discriminator=randint(0, 40000000))
+        self.test_session.send_packet()
+        self.pg0.enable_capture()
+        p = self.pg0.wait_for_packet(1)
+        self.assert_equal(
+            p[BFD].your_discriminator,
+            self.test_session.my_discriminator,
+            "BFD - your discriminator",
+        )
+        self.assert_equal(p[BFD].state, BFDState.init, BFDState)
+        self.test_session.update(
+            your_discriminator=p[BFD].my_discriminator, state=BFDState.up
+        )
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.init)
+        self.logger.info("BFD: Sending Up")
+        self.test_session.send_packet()
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.up)
+        self.logger.info("BFD: Session is Up")
+        self.test_session.update(state=BFDState.up)
+        self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
 
     def test_session_down(self):
-        """ bring BFD session down """
-        self.bfd_session_up()
-        self.bfd_session_down()
+        """bring BFD session down"""
+        bfd_session_up(self)
+        bfd_session_down(self)
 
     def test_hold_up(self):
-        """ hold BFD session up """
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        """hold BFD session up"""
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
             self.test_session.send_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_slow_timer(self):
-        """ verify slow periodic control frames while session down """
-        expected_packets = 3
-        self.logger.info("BFD: Waiting for %d BFD packets" % expected_packets)
-        self.wait_for_bfd_packet(2)
-        for i in range(expected_packets):
-            before = time.time()
-            self.wait_for_bfd_packet(2)
-            after = time.time()
+        """verify slow periodic control frames while session down"""
+        packet_count = 3
+        self.logger.info("BFD: Waiting for %d BFD packets", packet_count)
+        prev_packet = wait_for_bfd_packet(self, 2)
+        for dummy in range(packet_count):
+            next_packet = wait_for_bfd_packet(self, 2)
+            time_diff = next_packet.time - prev_packet.time
             # spec says the range should be <0.75, 1>, allow extra 0.05 margin
             # to work around timing issues
-            self.assert_in_range(
-                after - before, 0.70, 1.05, "time between slow packets")
-            before = after
+            self.assert_in_range(time_diff, 0.70, 1.05, "time between slow packets")
+            prev_packet = next_packet
 
     def test_zero_remote_min_rx(self):
-        """ no packets when zero BFD RemoteMinRxInterval """
-        self.pg_enable_capture([self.pg0])
-        p, timeout = self.wait_for_bfd_packet(2)
-        self.test_session.update(my_discriminator=randint(0, 40000000),
-                                 your_discriminator=p[BFD].my_discriminator,
-                                 state=BFDState.init,
-                                 required_min_rx_interval=0)
+        """no packets when zero remote required min rx interval"""
+        bfd_session_up(self)
+        self.test_session.update(required_min_rx=0)
         self.test_session.send_packet()
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
-        self.verify_event(e, expected_state=BFDState.up)
-
-        cap = 2 * self.vpp_session.desired_min_tx *\
-            self.vpp_session.detect_mult
-        now = time.time()
-        count = 0
-        # busy wait here, trying to collect a packet or event, vpp is not
-        # allowed to send packets and the session will timeout first - so the
-        # Up->Down event must arrive before any packets do
-        while time.time() < now + cap / us_in_sec:
+        for dummy in range(self.test_session.detect_mult):
+            self.sleep(
+                self.vpp_session.required_min_rx / USEC_IN_SEC,
+                "sleep before transmitting bfd packet",
+            )
+            self.test_session.send_packet()
             try:
-                p, ttp = self.wait_for_bfd_packet(timeout=0)
+                p = wait_for_bfd_packet(self, timeout=0)
                 self.logger.error(ppp("Received unexpected packet:", p))
-                count += 1
-            except:
+            except CaptureTimeoutError:
                 pass
-            events = self.vapi.collect_events()
-            if len(events) > 0:
-                self.verify_event(events[0], BFDState.down)
-                break
-        self.assert_equal(count, 0, "number of packets received")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
+        self.test_session.update(required_min_rx=300000)
+        for dummy in range(3):
+            self.test_session.send_packet()
+            wait_for_bfd_packet(
+                self, timeout=self.test_session.required_min_rx / USEC_IN_SEC
+            )
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_conn_down(self):
-        """ verify session goes down after inactivity """
-        self.bfd_session_up()
-        self.wait_for_bfd_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        self.wait_for_bfd_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
-        self.verify_event(e, expected_state=BFDState.down)
+        """verify session goes down after inactivity"""
+        bfd_session_up(self)
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        self.sleep(detection_time, "waiting for BFD session time-out")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.down)
+
+    def test_peer_discr_reset_sess_down(self):
+        """peer discriminator reset after session goes down"""
+        bfd_session_up(self)
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        self.sleep(detection_time, "waiting for BFD session time-out")
+        self.test_session.my_discriminator = 0
+        wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
 
     def test_large_required_min_rx(self):
-        """ large remote RequiredMinRxInterval """
-        self.bfd_session_up()
-        self.wait_for_bfd_packet()
+        """large remote required min rx interval"""
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
         interval = 3000000
-        self.test_session.update(required_min_rx_interval=interval)
+        self.test_session.update(required_min_rx=interval)
         self.test_session.send_packet()
-        now = time.time()
+        time_mark = time.time()
         count = 0
         # busy wait here, trying to collect a packet or event, vpp is not
         # allowed to send packets and the session will timeout first - so the
         # Up->Down event must arrive before any packets do
-        while time.time() < now + interval / us_in_sec:
+        while time.time() < time_mark + interval / USEC_IN_SEC:
             try:
-                p, ttp = self.wait_for_bfd_packet(timeout=0)
+                p = wait_for_bfd_packet(self, timeout=0)
+                # if vpp managed to send a packet before we did the session
+                # session update, then that's fine, ignore it
+                if p.time < time_mark - self.vpp_clock_offset:
+                    continue
                 self.logger.error(ppp("Received unexpected packet:", p))
                 count += 1
-            except:
+            except CaptureTimeoutError:
                 pass
             events = self.vapi.collect_events()
             if len(events) > 0:
-                self.verify_event(events[0], BFDState.down)
+                verify_event(self, events[0], BFDState.down)
                 break
         self.assert_equal(count, 0, "number of packets received")
 
-    def test_immediate_remote_min_rx_reduce(self):
-        """ immediately honor remote min rx reduction """
+    def test_immediate_remote_min_rx_reduction(self):
+        """immediately honor remote required min rx reduction"""
         self.vpp_session.remove_vpp_config()
         self.vpp_session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip4, desired_min_tx=10000)
-        self.pg_enable_capture([self.pg0])
+            self, self.pg0, self.pg0.remote_ip4, desired_min_tx=10000
+        )
+        self.pg0.enable_capture()
         self.vpp_session.add_vpp_config()
-        self.test_session.update(desired_min_tx_interval=1000000,
-                                 required_min_rx_interval=1000000)
-        self.bfd_session_up()
-        self.wait_for_bfd_packet()
-        interval = 100000
-        self.test_session.update(required_min_rx_interval=interval)
+        self.test_session.update(desired_min_tx=1000000, required_min_rx=1000000)
+        bfd_session_up(self)
+        reference_packet = wait_for_bfd_packet(self)
+        time_mark = time.time()
+        interval = 300000
+        self.test_session.update(required_min_rx=interval)
         self.test_session.send_packet()
-        p, ttp = self.wait_for_bfd_packet()
-        # allow extra 10% to work around timing issues, first packet is special
-        self.assert_in_range(ttp, 0, 1.10 * interval / us_in_sec,
-                             "time between BFD packets")
-        p, ttp = self.wait_for_bfd_packet()
-        self.assert_in_range(ttp, .9 * .75 * interval / us_in_sec,
-                             1.10 * interval / us_in_sec,
-                             "time between BFD packets")
-        p, ttp = self.wait_for_bfd_packet()
-        self.assert_in_range(ttp, .9 * .75 * interval / us_in_sec,
-                             1.10 * interval / us_in_sec,
-                             "time between BFD packets")
+        extra_time = time.time() - time_mark
+        p = wait_for_bfd_packet(self)
+        # first packet is allowed to be late by time we spent doing the update
+        # calculated in extra_time
+        self.assert_in_range(
+            p.time - reference_packet.time,
+            0.95 * 0.75 * interval / USEC_IN_SEC,
+            1.05 * interval / USEC_IN_SEC + extra_time,
+            "time between BFD packets",
+        )
+        reference_packet = p
+        for dummy in range(3):
+            p = wait_for_bfd_packet(self)
+            diff = p.time - reference_packet.time
+            self.assert_in_range(
+                diff,
+                0.95 * 0.75 * interval / USEC_IN_SEC,
+                1.05 * interval / USEC_IN_SEC,
+                "time between BFD packets",
+            )
+            reference_packet = p
 
     def test_modify_req_min_rx_double(self):
-        """ modify session - double required min rx """
-        self.bfd_session_up()
-        self.wait_for_bfd_packet()
-        self.test_session.update(desired_min_tx_interval=10000,
-                                 required_min_rx_interval=10000)
+        """modify session - double required min rx"""
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.test_session.update(desired_min_tx=10000, required_min_rx=10000)
         self.test_session.send_packet()
-        # first double required min rx
+        # double required min rx
         self.vpp_session.modify_parameters(
-            required_min_rx=2 * self.vpp_session.required_min_rx)
-        p, ttp = self.wait_for_bfd_packet()
+            required_min_rx=2 * self.vpp_session.required_min_rx
+        )
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
         # poll bit needs to be set
-        self.assertIn("P", p.sprintf("%BFD.flags%"),
-                      "Poll bit not set in BFD packet")
+        self.assertIn("P", p.sprintf("%BFD.flags%"), "Poll bit not set in BFD packet")
         # finish poll sequence with final packet
         final = self.test_session.create_packet()
         final[BFD].flags = "F"
+        timeout = (
+            self.test_session.detect_mult
+            * max(self.test_session.desired_min_tx, self.vpp_session.required_min_rx)
+            / USEC_IN_SEC
+        )
         self.test_session.send_packet(final)
-        # now we can wait 0.9*3*req-min-rx and the session should still be up
-        self.sleep(0.9 * self.vpp_session.detect_mult *
-                   self.vpp_session.required_min_rx / us_in_sec)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        time_mark = time.time()
+        e = self.vapi.wait_for_event(2 * timeout, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.down)
+        time_to_event = time.time() - time_mark
+        self.assert_in_range(
+            time_to_event, 0.9 * timeout, 1.1 * timeout, "session timeout"
+        )
 
     def test_modify_req_min_rx_halve(self):
-        """ modify session - halve required min rx """
+        """modify session - halve required min rx"""
         self.vpp_session.modify_parameters(
-            required_min_rx=2 * self.vpp_session.required_min_rx)
-        self.bfd_session_up()
-        self.wait_for_bfd_packet()
-        self.test_session.update(desired_min_tx_interval=10000,
-                                 required_min_rx_interval=10000)
+            required_min_rx=2 * self.vpp_session.required_min_rx
+        )
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.test_session.update(desired_min_tx=10000, required_min_rx=10000)
         self.test_session.send_packet()
-        p, ttp = self.wait_for_bfd_packet()
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
         # halve required min rx
         old_required_min_rx = self.vpp_session.required_min_rx
         self.vpp_session.modify_parameters(
-            required_min_rx=0.5 * self.vpp_session.required_min_rx)
+            required_min_rx=self.vpp_session.required_min_rx // 2
+        )
         # now we wait 0.8*3*old-req-min-rx and the session should still be up
-        self.sleep(0.8 * self.vpp_session.detect_mult *
-                   old_required_min_rx / us_in_sec)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        p, ttp = self.wait_for_bfd_packet()
+        self.sleep(
+            0.8 * self.vpp_session.detect_mult * old_required_min_rx / USEC_IN_SEC,
+            "wait before finishing poll sequence",
+        )
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
+        p = wait_for_bfd_packet(self)
         # poll bit needs to be set
-        self.assertIn("P", p.sprintf("%BFD.flags%"),
-                      "Poll bit not set in BFD packet")
+        self.assertIn("P", p.sprintf("%BFD.flags%"), "Poll bit not set in BFD packet")
         # finish poll sequence with final packet
         final = self.test_session.create_packet()
         final[BFD].flags = "F"
         self.test_session.send_packet(final)
         # now the session should time out under new conditions
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
         before = time.time()
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        e = self.vapi.wait_for_event(2 * detection_time, "bfd_udp_session_event")
         after = time.time()
-        detection_time = self.vpp_session.detect_mult *\
-            self.vpp_session.required_min_rx / us_in_sec
-        self.assert_in_range(after - before,
-                             0.9 * detection_time,
-                             1.1 * detection_time,
-                             "time before bfd session goes down")
-        self.verify_event(e, expected_state=BFDState.down)
-
-    def test_modify_des_min_tx(self):
-        """ modify desired min tx interval """
-        pass
+        self.assert_in_range(
+            after - before,
+            0.9 * detection_time,
+            1.1 * detection_time,
+            "time before bfd session goes down",
+        )
+        verify_event(self, e, expected_state=BFDState.down)
 
     def test_modify_detect_mult(self):
-        """ modify detect multiplier """
-        self.bfd_session_up()
+        """modify detect multiplier"""
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
         self.vpp_session.modify_parameters(detect_mult=1)
-        p, ttp = self.wait_for_bfd_packet()
-        self.assert_equal(self.vpp_session.detect_mult,
-                          p[BFD].detect_mult,
-                          "detect mult")
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(
+            self.vpp_session.detect_mult, p[BFD].detect_mult, "detect mult"
+        )
         # poll bit must not be set
-        self.assertNotIn("P", p.sprintf("%BFD.flags%"),
-                         "Poll bit not set in BFD packet")
+        self.assertNotIn(
+            "P", p.sprintf("%BFD.flags%"), "Poll bit not set in BFD packet"
+        )
         self.vpp_session.modify_parameters(detect_mult=10)
-        p, ttp = self.wait_for_bfd_packet()
-        self.assert_equal(self.vpp_session.detect_mult,
-                          p[BFD].detect_mult,
-                          "detect mult")
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(
+            self.vpp_session.detect_mult, p[BFD].detect_mult, "detect mult"
+        )
         # poll bit must not be set
-        self.assertNotIn("P", p.sprintf("%BFD.flags%"),
-                         "Poll bit not set in BFD packet")
+        self.assertNotIn(
+            "P", p.sprintf("%BFD.flags%"), "Poll bit not set in BFD packet"
+        )
+
+    def test_queued_poll(self):
+        """test poll sequence queueing"""
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx
+        )
+        p = wait_for_bfd_packet(self)
+        poll_sequence_start = time.time()
+        poll_sequence_length_min = 0.5
+        send_final_after = time.time() + poll_sequence_length_min
+        # poll bit needs to be set
+        self.assertIn("P", p.sprintf("%BFD.flags%"), "Poll bit not set in BFD packet")
+        self.assert_equal(
+            p[BFD].required_min_rx_interval,
+            self.vpp_session.required_min_rx,
+            "BFD required min rx interval",
+        )
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx
+        )
+        # 2nd poll sequence should be queued now
+        # don't send the reply back yet, wait for some time to emulate
+        # longer round-trip time
+        packet_count = 0
+        while time.time() < send_final_after:
+            self.test_session.send_packet()
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(
+                len(self.vapi.collect_events()), 0, "number of bfd events"
+            )
+            self.assert_equal(
+                p[BFD].required_min_rx_interval,
+                self.vpp_session.required_min_rx,
+                "BFD required min rx interval",
+            )
+            packet_count += 1
+            # poll bit must be set
+            self.assertIn(
+                "P", p.sprintf("%BFD.flags%"), "Poll bit not set in BFD packet"
+            )
+        final = self.test_session.create_packet()
+        final[BFD].flags = "F"
+        self.test_session.send_packet(final)
+        # finish 1st with final
+        poll_sequence_length = time.time() - poll_sequence_start
+        # vpp must wait for some time before starting new poll sequence
+        poll_no_2_started = False
+        for dummy in range(2 * packet_count):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(
+                len(self.vapi.collect_events()), 0, "number of bfd events"
+            )
+            if "P" in p.sprintf("%BFD.flags%"):
+                poll_no_2_started = True
+                if time.time() < poll_sequence_start + poll_sequence_length:
+                    raise Exception("VPP started 2nd poll sequence too soon")
+                final = self.test_session.create_packet()
+                final[BFD].flags = "F"
+                self.test_session.send_packet(final)
+                break
+            else:
+                self.test_session.send_packet()
+        self.assertTrue(poll_no_2_started, "2nd poll sequence not performed")
+        # finish 2nd with final
+        final = self.test_session.create_packet()
+        final[BFD].flags = "F"
+        self.test_session.send_packet(final)
+        p = wait_for_bfd_packet(self)
+        # poll bit must not be set
+        self.assertNotIn("P", p.sprintf("%BFD.flags%"), "Poll bit set in BFD packet")
+
+    # returning inconsistent results requiring retries in per-patch tests
+    @unittest.skipUnless(config.extended, "part of extended tests")
+    def test_poll_response(self):
+        """test correct response to control frame with poll bit set"""
+        bfd_session_up(self)
+        poll = self.test_session.create_packet()
+        poll[BFD].flags = "P"
+        self.test_session.send_packet(poll)
+        final = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset
+        )
+        self.assertIn("F", final.sprintf("%BFD.flags%"))
+
+    def test_no_periodic_if_remote_demand(self):
+        """no periodic frames outside poll sequence if remote demand set"""
+        bfd_session_up(self)
+        demand = self.test_session.create_packet()
+        demand[BFD].flags = "D"
+        self.test_session.send_packet(demand)
+        transmit_time = (
+            0.9
+            * max(self.vpp_session.required_min_rx, self.test_session.desired_min_tx)
+            / USEC_IN_SEC
+        )
+        count = 0
+        for dummy in range(self.test_session.detect_mult * 2):
+            self.sleep(transmit_time)
+            self.test_session.send_packet(demand)
+            try:
+                p = wait_for_bfd_packet(self, timeout=0)
+                self.logger.error(ppp("Received unexpected packet:", p))
+                count += 1
+            except CaptureTimeoutError:
+                pass
+        events = self.vapi.collect_events()
+        for e in events:
+            self.logger.error("Received unexpected event: %s", e)
+        self.assert_equal(count, 0, "number of packets received")
+        self.assert_equal(len(events), 0, "number of events received")
+
+    def test_echo_looped_back(self):
+        """echo packets looped back"""
+        bfd_session_up(self)
+        stats_before = bfd_grab_stats_snapshot(self)
+        self.pg0.enable_capture()
+        echo_packet_count = 10
+        # random source port low enough to increment a few times..
+        udp_sport_tx = randint(1, 50000)
+        udp_sport_rx = udp_sport_tx
+        echo_packet = (
+            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
+            / IP(src=self.pg0.remote_ip4, dst=self.pg0.remote_ip4)
+            / UDP(dport=BFD.udp_dport_echo)
+            / Raw("this should be looped back")
+        )
+        for dummy in range(echo_packet_count):
+            self.sleep(0.01, "delay between echo packets")
+            echo_packet[UDP].sport = udp_sport_tx
+            udp_sport_tx += 1
+            self.logger.debug(ppp("Sending packet:", echo_packet))
+            self.pg0.add_stream(echo_packet)
+            self.pg_start()
+            self.logger.debug(self.vapi.ppcli("show trace"))
+        counter = 0
+        bfd_control_packets_rx = 0
+        while counter < echo_packet_count:
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            ether = p[Ether]
+            self.assert_equal(self.pg0.remote_mac, ether.dst, "Destination MAC")
+            self.assert_equal(self.pg0.local_mac, ether.src, "Source MAC")
+            ip = p[IP]
+            self.assert_equal(self.pg0.remote_ip4, ip.dst, "Destination IP")
+            udp = p[UDP]
+            if udp.dport == BFD.udp_dport:
+                bfd_control_packets_rx += 1
+                continue
+            self.assert_equal(self.pg0.remote_ip4, ip.src, "Source IP")
+            self.assert_equal(udp.dport, BFD.udp_dport_echo, "UDP destination port")
+            self.assert_equal(udp.sport, udp_sport_rx, "UDP source port")
+            udp_sport_rx += 1
+            # need to compare the hex payload here, otherwise BFD_vpp_echo
+            # gets in way
+            self.assertEqual(
+                scapy.compat.raw(p[UDP].payload),
+                scapy.compat.raw(echo_packet[UDP].payload),
+                "Received packet is not the echo packet sent",
+            )
+            counter += 1
+        self.assert_equal(
+            udp_sport_tx,
+            udp_sport_rx,
+            "UDP source port (== ECHO packet identifier for test purposes)",
+        )
+        stats_after = bfd_grab_stats_snapshot(self)
+        diff = bfd_stats_diff(stats_before, stats_after)
+        self.assertEqual(0, diff.rx, "RX counter bumped but no BFD packets sent")
+        self.assertEqual(
+            0, diff.rx_echo, "RX echo counter bumped but no BFD session exists"
+        )
+        self.assertEqual(
+            0, diff.tx_echo, "TX echo counter bumped but no BFD session exists"
+        )
+
+    def test_echo(self):
+        """echo function"""
+        stats_before = bfd_grab_stats_snapshot(self)
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        # echo shouldn't work without echo source set
+        for dummy in range(10):
+            sleep = self.vpp_session.required_min_rx / USEC_IN_SEC
+            self.sleep(sleep, "delay before sending bfd packet")
+            self.test_session.send_packet()
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(
+            p[BFD].required_min_rx_interval,
+            self.vpp_session.required_min_rx,
+            "BFD required min rx interval",
+        )
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        echo_seen = False
+        # should be turned on - loopback echo packets
+        for dummy in range(3):
+            loop_until = time.time() + 0.75 * detection_time
+            while time.time() < loop_until:
+                p = self.pg0.wait_for_packet(1)
+                self.logger.debug(ppp("Got packet:", p))
+                if p[UDP].dport == BFD.udp_dport_echo:
+                    self.assert_equal(p[IP].dst, self.pg0.local_ip4, "BFD ECHO dst IP")
+                    self.assertNotEqual(
+                        p[IP].src,
+                        self.loopback0.local_ip4,
+                        "BFD ECHO src IP equal to loopback IP",
+                    )
+                    self.logger.debug(ppp("Looping back packet:", p))
+                    self.assert_equal(
+                        p[Ether].dst,
+                        self.pg0.remote_mac,
+                        "ECHO packet destination MAC address",
+                    )
+                    p[Ether].dst = self.pg0.local_mac
+                    self.pg0.add_stream(p)
+                    self.test_session.rx_packets_echo += 1
+                    self.test_session.tx_packets_echo += 1
+                    self.pg_start()
+                    echo_seen = True
+                elif p.haslayer(BFD):
+                    self.test_session.rx_packets += 1
+                    if echo_seen:
+                        self.assertGreaterEqual(
+                            p[BFD].required_min_rx_interval, 1000000
+                        )
+                    if "P" in p.sprintf("%BFD.flags%"):
+                        final = self.test_session.create_packet()
+                        final[BFD].flags = "F"
+                        self.test_session.send_packet(final)
+                else:
+                    raise Exception(ppp("Received unknown packet:", p))
 
+                self.assert_equal(
+                    len(self.vapi.collect_events()), 0, "number of bfd events"
+                )
+            self.test_session.send_packet()
+        self.assertTrue(echo_seen, "No echo packets received")
+
+        stats_after = bfd_grab_stats_snapshot(self)
+        diff = bfd_stats_diff(stats_before, stats_after)
+        # our rx is vpp tx and vice versa, also tolerate one packet off
+        self.assert_in_range(
+            self.test_session.tx_packets, diff.rx - 1, diff.rx + 1, "RX counter"
+        )
+        self.assert_in_range(
+            self.test_session.rx_packets, diff.tx - 1, diff.tx + 1, "TX counter"
+        )
+        self.assert_in_range(
+            self.test_session.tx_packets_echo,
+            diff.rx_echo - 1,
+            diff.rx_echo + 1,
+            "RX echo counter",
+        )
+        self.assert_in_range(
+            self.test_session.rx_packets_echo,
+            diff.tx_echo - 1,
+            diff.tx_echo + 1,
+            "TX echo counter",
+        )
+
+    def test_echo_fail(self):
+        """session goes down if echo function fails"""
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        # echo function should be used now, but we will drop the echo packets
+        verified_diag = False
+        for dummy in range(3):
+            loop_until = time.time() + 0.75 * detection_time
+            while time.time() < loop_until:
+                p = self.pg0.wait_for_packet(1)
+                self.logger.debug(ppp("Got packet:", p))
+                if p[UDP].dport == BFD.udp_dport_echo:
+                    # dropped
+                    pass
+                elif p.haslayer(BFD):
+                    if "P" in p.sprintf("%BFD.flags%"):
+                        self.assertGreaterEqual(
+                            p[BFD].required_min_rx_interval, 1000000
+                        )
+                        final = self.test_session.create_packet()
+                        final[BFD].flags = "F"
+                        self.test_session.send_packet(final)
+                    if p[BFD].state == BFDState.down:
+                        self.assert_equal(
+                            p[BFD].diag, BFDDiagCode.echo_function_failed, BFDDiagCode
+                        )
+                        verified_diag = True
+                else:
+                    raise Exception(ppp("Received unknown packet:", p))
+            self.test_session.send_packet()
+        events = self.vapi.collect_events()
+        self.assert_equal(len(events), 1, "number of bfd events")
+        self.assert_equal(events[0].state, BFDState.down, BFDState)
+        self.assertTrue(verified_diag, "Incorrect diagnostics code received")
+
+    def test_echo_stop(self):
+        """echo function stops if peer sets required min echo rx zero"""
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        # wait for first echo packet
+        while True:
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            if p[UDP].dport == BFD.udp_dport_echo:
+                self.logger.debug(ppp("Looping back packet:", p))
+                p[Ether].dst = self.pg0.local_mac
+                self.pg0.add_stream(p)
+                self.pg_start()
+                break
+            elif p.haslayer(BFD):
+                # ignore BFD
+                pass
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+        self.test_session.update(required_min_echo_rx=0)
+        self.test_session.send_packet()
+        # echo packets shouldn't arrive anymore
+        for dummy in range(5):
+            wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+            self.test_session.send_packet()
+            events = self.vapi.collect_events()
+            self.assert_equal(len(events), 0, "number of bfd events")
+
+    def test_echo_source_removed(self):
+        """echo function stops if echo source is removed"""
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        # wait for first echo packet
+        while True:
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            if p[UDP].dport == BFD.udp_dport_echo:
+                self.logger.debug(ppp("Looping back packet:", p))
+                p[Ether].dst = self.pg0.local_mac
+                self.pg0.add_stream(p)
+                self.pg_start()
+                break
+            elif p.haslayer(BFD):
+                # ignore BFD
+                pass
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+        self.vapi.bfd_udp_del_echo_source()
+        self.test_session.send_packet()
+        # echo packets shouldn't arrive anymore
+        for dummy in range(5):
+            wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+            self.test_session.send_packet()
+            events = self.vapi.collect_events()
+            self.assert_equal(len(events), 0, "number of bfd events")
+
+    def test_stale_echo(self):
+        """stale echo packets don't keep a session up"""
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        self.test_session.send_packet()
+        # should be turned on - loopback echo packets
+        echo_packet = None
+        timeout_at = None
+        timeout_ok = False
+        for dummy in range(10 * self.vpp_session.detect_mult):
+            p = self.pg0.wait_for_packet(1)
+            if p[UDP].dport == BFD.udp_dport_echo:
+                if echo_packet is None:
+                    self.logger.debug(ppp("Got first echo packet:", p))
+                    echo_packet = p
+                    timeout_at = (
+                        time.time()
+                        + self.vpp_session.detect_mult
+                        * self.test_session.required_min_echo_rx
+                        / USEC_IN_SEC
+                    )
+                else:
+                    self.logger.debug(ppp("Got followup echo packet:", p))
+                self.logger.debug(ppp("Looping back first echo packet:", p))
+                echo_packet[Ether].dst = self.pg0.local_mac
+                self.pg0.add_stream(echo_packet)
+                self.pg_start()
+            elif p.haslayer(BFD):
+                self.logger.debug(ppp("Got packet:", p))
+                if "P" in p.sprintf("%BFD.flags%"):
+                    final = self.test_session.create_packet()
+                    final[BFD].flags = "F"
+                    self.test_session.send_packet(final)
+                if p[BFD].state == BFDState.down:
+                    self.assertIsNotNone(
+                        timeout_at,
+                        "Session went down before first echo packet received",
+                    )
+                    now = time.time()
+                    self.assertGreaterEqual(
+                        now,
+                        timeout_at,
+                        "Session timeout at %s, but is expected at %s"
+                        % (now, timeout_at),
+                    )
+                    self.assert_equal(
+                        p[BFD].diag, BFDDiagCode.echo_function_failed, BFDDiagCode
+                    )
+                    events = self.vapi.collect_events()
+                    self.assert_equal(len(events), 1, "number of bfd events")
+                    self.assert_equal(events[0].state, BFDState.down, BFDState)
+                    timeout_ok = True
+                    break
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+            self.test_session.send_packet()
+        self.assertTrue(timeout_ok, "Expected timeout event didn't occur")
 
-class BFD6TestCase(VppTestCase, BFDCommonCode):
-    """Bidirectional Forwarding Detection (BFD) (IPv6) """
+    def test_invalid_echo_checksum(self):
+        """echo packets with invalid checksum don't keep a session up"""
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        self.test_session.send_packet()
+        # should be turned on - loopback echo packets
+        timeout_at = None
+        timeout_ok = False
+        for dummy in range(10 * self.vpp_session.detect_mult):
+            p = self.pg0.wait_for_packet(1)
+            if p[UDP].dport == BFD.udp_dport_echo:
+                self.logger.debug(ppp("Got echo packet:", p))
+                if timeout_at is None:
+                    timeout_at = (
+                        time.time()
+                        + self.vpp_session.detect_mult
+                        * self.test_session.required_min_echo_rx
+                        / USEC_IN_SEC
+                    )
+                p[BFD_vpp_echo].checksum = getrandbits(64)
+                p[Ether].dst = self.pg0.local_mac
+                self.logger.debug(ppp("Looping back modified echo packet:", p))
+                self.pg0.add_stream(p)
+                self.pg_start()
+            elif p.haslayer(BFD):
+                self.logger.debug(ppp("Got packet:", p))
+                if "P" in p.sprintf("%BFD.flags%"):
+                    final = self.test_session.create_packet()
+                    final[BFD].flags = "F"
+                    self.test_session.send_packet(final)
+                if p[BFD].state == BFDState.down:
+                    self.assertIsNotNone(
+                        timeout_at,
+                        "Session went down before first echo packet received",
+                    )
+                    now = time.time()
+                    self.assertGreaterEqual(
+                        now,
+                        timeout_at,
+                        "Session timeout at %s, but is expected at %s"
+                        % (now, timeout_at),
+                    )
+                    self.assert_equal(
+                        p[BFD].diag, BFDDiagCode.echo_function_failed, BFDDiagCode
+                    )
+                    events = self.vapi.collect_events()
+                    self.assert_equal(len(events), 1, "number of bfd events")
+                    self.assert_equal(events[0].state, BFDState.down, BFDState)
+                    timeout_ok = True
+                    break
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+            self.test_session.send_packet()
+        self.assertTrue(timeout_ok, "Expected timeout event didn't occur")
+
+    def test_admin_up_down(self):
+        """put session admin-up and admin-down"""
+        bfd_session_up(self)
+        self.vpp_session.admin_down()
+        self.pg0.enable_capture()
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.admin_down)
+        for dummy in range(2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.admin_down, BFDState)
+        # try to bring session up - shouldn't be possible
+        self.test_session.update(state=BFDState.init)
+        self.test_session.send_packet()
+        for dummy in range(2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.admin_down, BFDState)
+        self.vpp_session.admin_up()
+        self.test_session.update(state=BFDState.down)
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.down)
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].state, BFDState.down, BFDState)
+        self.test_session.send_packet()
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].state, BFDState.init, BFDState)
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.init)
+        self.test_session.update(state=BFDState.up)
+        self.test_session.send_packet()
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.up)
+
+    def test_config_change_remote_demand(self):
+        """configuration change while peer in demand mode"""
+        bfd_session_up(self)
+        demand = self.test_session.create_packet()
+        demand[BFD].flags = "D"
+        self.test_session.send_packet(demand)
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx
+        )
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        # poll bit must be set
+        self.assertIn("P", p.sprintf("%BFD.flags%"), "Poll bit not set")
+        # terminate poll sequence
+        final = self.test_session.create_packet()
+        final[BFD].flags = "D+F"
+        self.test_session.send_packet(final)
+        # vpp should be quiet now again
+        transmit_time = (
+            0.9
+            * max(self.vpp_session.required_min_rx, self.test_session.desired_min_tx)
+            / USEC_IN_SEC
+        )
+        count = 0
+        for dummy in range(self.test_session.detect_mult * 2):
+            self.sleep(transmit_time)
+            self.test_session.send_packet(demand)
+            try:
+                p = wait_for_bfd_packet(self, timeout=0)
+                self.logger.error(ppp("Received unexpected packet:", p))
+                count += 1
+            except CaptureTimeoutError:
+                pass
+        events = self.vapi.collect_events()
+        for e in events:
+            self.logger.error("Received unexpected event: %s", e)
+        self.assert_equal(count, 0, "number of packets received")
+        self.assert_equal(len(events), 0, "number of events received")
+
+    def test_intf_deleted(self):
+        """interface with bfd session deleted"""
+        intf = VppLoInterface(self)
+        intf.config_ip4()
+        intf.admin_up()
+        sw_if_index = intf.sw_if_index
+        vpp_session = VppBFDUDPSession(self, intf, intf.remote_ip4)
+        vpp_session.add_vpp_config()
+        vpp_session.admin_up()
+        intf.remove_vpp_config()
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        self.assert_equal(e.sw_if_index, sw_if_index, "sw_if_index")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+
+@tag_run_solo
+@tag_fixme_vpp_workers
+class BFD6TestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (IPv6)"""
+
+    pg0 = None
+    vpp_clock_offset = None
+    vpp_session = None
+    test_session = None
 
     @classmethod
     def setUpClass(cls):
         super(BFD6TestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
         try:
             cls.create_pg_interfaces([0])
             cls.pg0.config_ip6()
             cls.pg0.configure_ipv6_neighbors()
             cls.pg0.admin_up()
             cls.pg0.resolve_ndp()
+            cls.create_loopback_interfaces(1)
+            cls.loopback0 = cls.lo_interfaces[0]
+            cls.loopback0.config_ip6()
+            cls.loopback0.admin_up()
 
         except Exception:
             super(BFD6TestCase, cls).tearDownClass()
             raise
 
+    @classmethod
+    def tearDownClass(cls):
+        super(BFD6TestCase, cls).tearDownClass()
+
     def setUp(self):
         super(BFD6TestCase, self).setUp()
         self.factory = AuthKeyFactory()
         self.vapi.want_bfd_events()
-        self.pg_enable_capture([self.pg0])
+        self.pg0.enable_capture()
         try:
-            self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                                self.pg0.remote_ip6,
-                                                af=AF_INET6)
+            self.bfd_udp4_sessions = self.statistics["/bfd/udp4/sessions"]
+            self.bfd_udp6_sessions = self.statistics["/bfd/udp6/sessions"]
+            self.vpp_session = VppBFDUDPSession(
+                self, self.pg0, self.pg0.remote_ip6, af=AF_INET6
+            )
             self.vpp_session.add_vpp_config()
             self.vpp_session.admin_up()
             self.test_session = BFDTestSession(self, self.pg0, AF_INET6)
             self.logger.debug(self.vapi.cli("show adj nbr"))
-        except:
+        except BaseException:
             self.vapi.want_bfd_events(enable_disable=0)
             raise
 
     def tearDown(self):
-        BFDCommonCode.tearDown(self)
-        VppTestCase.tearDown(self)
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=0)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFD6TestCase, self).tearDown()
 
     def test_session_up(self):
-        """ bring BFD session up """
-        self.bfd_session_up()
+        """bring BFD session up"""
+        bfd_session_up(self)
+        bfd_udp4_sessions = self.statistics["/bfd/udp4/sessions"]
+        bfd_udp6_sessions = self.statistics["/bfd/udp6/sessions"]
+        self.assert_equal(bfd_udp4_sessions, self.bfd_udp4_sessions)
+        self.assert_equal(bfd_udp6_sessions - self.bfd_udp6_sessions, 1)
+
+    def test_session_up_by_ip(self):
+        """bring BFD session up - first frame looked up by address pair"""
+        self.logger.info("BFD: Sending Slow control frame")
+        self.test_session.update(my_discriminator=randint(0, 40000000))
+        self.test_session.send_packet()
+        self.pg0.enable_capture()
+        p = self.pg0.wait_for_packet(1)
+        self.assert_equal(
+            p[BFD].your_discriminator,
+            self.test_session.my_discriminator,
+            "BFD - your discriminator",
+        )
+        self.assert_equal(p[BFD].state, BFDState.init, BFDState)
+        self.test_session.update(
+            your_discriminator=p[BFD].my_discriminator, state=BFDState.up
+        )
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.init)
+        self.logger.info("BFD: Sending Up")
+        self.test_session.send_packet()
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        verify_event(self, e, expected_state=BFDState.up)
+        self.logger.info("BFD: Session is Up")
+        self.test_session.update(state=BFDState.up)
+        self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
 
     def test_hold_up(self):
-        """ hold BFD session up """
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        """hold BFD session up"""
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
             self.test_session.send_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
 
+    def test_echo_looped_back(self):
+        """echo packets looped back"""
+        bfd_session_up(self)
+        stats_before = bfd_grab_stats_snapshot(self)
+        self.pg0.enable_capture()
+        echo_packet_count = 10
+        # random source port low enough to increment a few times..
+        udp_sport_tx = randint(1, 50000)
+        udp_sport_rx = udp_sport_tx
+        echo_packet = (
+            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
+            / IPv6(src=self.pg0.remote_ip6, dst=self.pg0.remote_ip6)
+            / UDP(dport=BFD.udp_dport_echo)
+            / Raw("this should be looped back")
+        )
+        for dummy in range(echo_packet_count):
+            self.sleep(0.01, "delay between echo packets")
+            echo_packet[UDP].sport = udp_sport_tx
+            udp_sport_tx += 1
+            self.logger.debug(ppp("Sending packet:", echo_packet))
+            self.pg0.add_stream(echo_packet)
+            self.pg_start()
+        counter = 0
+        bfd_control_packets_rx = 0
+        while counter < echo_packet_count:
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            ether = p[Ether]
+            self.assert_equal(self.pg0.remote_mac, ether.dst, "Destination MAC")
+            self.assert_equal(self.pg0.local_mac, ether.src, "Source MAC")
+            ip = p[IPv6]
+            self.assert_equal(self.pg0.remote_ip6, ip.dst, "Destination IP")
+            udp = p[UDP]
+            if udp.dport == BFD.udp_dport:
+                bfd_control_packets_rx += 1
+                continue
+            self.assert_equal(self.pg0.remote_ip6, ip.src, "Source IP")
+            self.assert_equal(udp.dport, BFD.udp_dport_echo, "UDP destination port")
+            self.assert_equal(udp.sport, udp_sport_rx, "UDP source port")
+            udp_sport_rx += 1
+            # need to compare the hex payload here, otherwise BFD_vpp_echo
+            # gets in way
+            self.assertEqual(
+                scapy.compat.raw(p[UDP].payload),
+                scapy.compat.raw(echo_packet[UDP].payload),
+                "Received packet is not the echo packet sent",
+            )
+            counter += 1
+        self.assert_equal(
+            udp_sport_tx,
+            udp_sport_rx,
+            "UDP source port (== ECHO packet identifier for test purposes)",
+        )
+        stats_after = bfd_grab_stats_snapshot(self)
+        diff = bfd_stats_diff(stats_before, stats_after)
+        self.assertEqual(0, diff.rx, "RX counter bumped but no BFD packets sent")
+        self.assertEqual(
+            0, diff.rx_echo, "RX echo counter bumped but no BFD session exists"
+        )
+        self.assertEqual(
+            0, diff.tx_echo, "TX echo counter bumped but no BFD session exists"
+        )
+
+    def test_echo(self):
+        """echo function"""
+        stats_before = bfd_grab_stats_snapshot(self)
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        # echo shouldn't work without echo source set
+        for dummy in range(10):
+            sleep = self.vpp_session.required_min_rx / USEC_IN_SEC
+            self.sleep(sleep, "delay before sending bfd packet")
+            self.test_session.send_packet()
+        p = wait_for_bfd_packet(self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(
+            p[BFD].required_min_rx_interval,
+            self.vpp_session.required_min_rx,
+            "BFD required min rx interval",
+        )
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(sw_if_index=self.loopback0.sw_if_index)
+        echo_seen = False
+        # should be turned on - loopback echo packets
+        for dummy in range(3):
+            loop_until = time.time() + 0.75 * detection_time
+            while time.time() < loop_until:
+                p = self.pg0.wait_for_packet(1)
+                self.logger.debug(ppp("Got packet:", p))
+                if p[UDP].dport == BFD.udp_dport_echo:
+                    self.assert_equal(
+                        p[IPv6].dst, self.pg0.local_ip6, "BFD ECHO dst IP"
+                    )
+                    self.assertNotEqual(
+                        p[IPv6].src,
+                        self.loopback0.local_ip6,
+                        "BFD ECHO src IP equal to loopback IP",
+                    )
+                    self.logger.debug(ppp("Looping back packet:", p))
+                    self.assert_equal(
+                        p[Ether].dst,
+                        self.pg0.remote_mac,
+                        "ECHO packet destination MAC address",
+                    )
+                    self.test_session.rx_packets_echo += 1
+                    self.test_session.tx_packets_echo += 1
+                    p[Ether].dst = self.pg0.local_mac
+                    self.pg0.add_stream(p)
+                    self.pg_start()
+                    echo_seen = True
+                elif p.haslayer(BFD):
+                    self.test_session.rx_packets += 1
+                    if echo_seen:
+                        self.assertGreaterEqual(
+                            p[BFD].required_min_rx_interval, 1000000
+                        )
+                    if "P" in p.sprintf("%BFD.flags%"):
+                        final = self.test_session.create_packet()
+                        final[BFD].flags = "F"
+                        self.test_session.send_packet(final)
+                else:
+                    raise Exception(ppp("Received unknown packet:", p))
+
+                self.assert_equal(
+                    len(self.vapi.collect_events()), 0, "number of bfd events"
+                )
+            self.test_session.send_packet()
+        self.assertTrue(echo_seen, "No echo packets received")
+
+        stats_after = bfd_grab_stats_snapshot(self)
+        diff = bfd_stats_diff(stats_before, stats_after)
+        # our rx is vpp tx and vice versa, also tolerate one packet off
+        self.assert_in_range(
+            self.test_session.tx_packets, diff.rx - 1, diff.rx + 1, "RX counter"
+        )
+        self.assert_in_range(
+            self.test_session.rx_packets, diff.tx - 1, diff.tx + 1, "TX counter"
+        )
+        self.assert_in_range(
+            self.test_session.tx_packets_echo,
+            diff.rx_echo - 1,
+            diff.rx_echo + 1,
+            "RX echo counter",
+        )
+        self.assert_in_range(
+            self.test_session.rx_packets_echo,
+            diff.tx_echo - 1,
+            diff.tx_echo + 1,
+            "TX echo counter",
+        )
+
+    def test_intf_deleted(self):
+        """interface with bfd session deleted"""
+        intf = VppLoInterface(self)
+        intf.config_ip6()
+        intf.admin_up()
+        sw_if_index = intf.sw_if_index
+        vpp_session = VppBFDUDPSession(self, intf, intf.remote_ip6, af=AF_INET6)
+        vpp_session.add_vpp_config()
+        vpp_session.admin_up()
+        intf.remove_vpp_config()
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_event")
+        self.assert_equal(e.sw_if_index, sw_if_index, "sw_if_index")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+
+@tag_run_solo
+class BFDFIBTestCase(VppTestCase):
+    """BFD-FIB interactions (IPv6)"""
+
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDFIBTestCase, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDFIBTestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDFIBTestCase, self).setUp()
+        self.create_pg_interfaces(range(1))
+
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+
+        for i in self.pg_interfaces:
+            i.admin_up()
+            i.config_ip6()
+            i.configure_ipv6_neighbors()
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=False)
+
+        super(BFDFIBTestCase, self).tearDown()
+
+    @staticmethod
+    def pkt_is_not_data_traffic(p):
+        """not data traffic implies BFD or the usual IPv6 ND/RA"""
+        if p.haslayer(BFD) or is_ipv6_misc(p):
+            return True
+        return False
+
+    def test_session_with_fib(self):
+        """BFD-FIB interactions"""
+
+        # packets to match against both of the routes
+        p = [
+            (
+                Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac)
+                / IPv6(src="3001::1", dst="2001::1")
+                / UDP(sport=1234, dport=1234)
+                / Raw(b"\xa5" * 100)
+            ),
+            (
+                Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac)
+                / IPv6(src="3001::1", dst="2002::1")
+                / UDP(sport=1234, dport=1234)
+                / Raw(b"\xa5" * 100)
+            ),
+        ]
+
+        # A recursive and a non-recursive route via a next-hop that
+        # will have a BFD session
+        ip_2001_s_64 = VppIpRoute(
+            self,
+            "2001::",
+            64,
+            [VppRoutePath(self.pg0.remote_ip6, self.pg0.sw_if_index)],
+        )
+        ip_2002_s_64 = VppIpRoute(
+            self, "2002::", 64, [VppRoutePath(self.pg0.remote_ip6, 0xFFFFFFFF)]
+        )
+        ip_2001_s_64.add_vpp_config()
+        ip_2002_s_64.add_vpp_config()
+
+        # bring the session up now the routes are present
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6
+        )
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(self, self.pg0, AF_INET6)
+
+        # session is up - traffic passes
+        bfd_session_up(self)
+
+        self.pg0.add_stream(p)
+        self.pg_start()
+        for packet in p:
+            captured = self.pg0.wait_for_packet(
+                1, filter_out_fn=self.pkt_is_not_data_traffic
+            )
+            self.assertEqual(captured[IPv6].dst, packet[IPv6].dst)
+
+        # session is up - traffic is dropped
+        bfd_session_down(self)
+
+        self.pg0.add_stream(p)
+        self.pg_start()
+        with self.assertRaises(CaptureTimeoutError):
+            self.pg0.wait_for_packet(1, self.pkt_is_not_data_traffic)
+
+        # session is up - traffic passes
+        bfd_session_up(self)
+
+        self.pg0.add_stream(p)
+        self.pg_start()
+        for packet in p:
+            captured = self.pg0.wait_for_packet(
+                1, filter_out_fn=self.pkt_is_not_data_traffic
+            )
+            self.assertEqual(captured[IPv6].dst, packet[IPv6].dst)
+
+
+@unittest.skipUnless(config.extended, "part of extended tests")
+class BFDTunTestCase(VppTestCase):
+    """BFD over GRE tunnel"""
+
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDTunTestCase, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDTunTestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDTunTestCase, self).setUp()
+        self.create_pg_interfaces(range(1))
+
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
 
-class BFDSHA1TestCase(VppTestCase, BFDCommonCode):
-    """Bidirectional Forwarding Detection (BFD) (SHA1 auth) """
+        for i in self.pg_interfaces:
+            i.admin_up()
+            i.config_ip4()
+            i.resolve_arp()
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=0)
+
+        super(BFDTunTestCase, self).tearDown()
+
+    @staticmethod
+    def pkt_is_not_data_traffic(p):
+        """not data traffic implies BFD or the usual IPv6 ND/RA"""
+        if p.haslayer(BFD) or is_ipv6_misc(p):
+            return True
+        return False
+
+    def test_bfd_o_gre(self):
+        """BFD-o-GRE"""
+
+        # A GRE interface over which to run a BFD session
+        gre_if = VppGreInterface(self, self.pg0.local_ip4, self.pg0.remote_ip4)
+        gre_if.add_vpp_config()
+        gre_if.admin_up()
+        gre_if.config_ip4()
+
+        # bring the session up now the routes are present
+        self.vpp_session = VppBFDUDPSession(
+            self, gre_if, gre_if.remote_ip4, is_tunnel=True
+        )
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+
+        self.test_session = BFDTestSession(
+            self,
+            gre_if,
+            AF_INET,
+            tunnel_header=(IP(src=self.pg0.remote_ip4, dst=self.pg0.local_ip4) / GRE()),
+            phy_interface=self.pg0,
+        )
+
+        # packets to match against both of the routes
+        p = [
+            (
+                Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac)
+                / IP(src=self.pg0.remote_ip4, dst=gre_if.remote_ip4)
+                / UDP(sport=1234, dport=1234)
+                / Raw(b"\xa5" * 100)
+            )
+        ]
+
+        # session is up - traffic passes
+        bfd_session_up(self)
+
+        self.send_and_expect(self.pg0, p, self.pg0)
+
+        # bring session down
+        bfd_session_down(self)
+
+
+@tag_run_solo
+class BFDSHA1TestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (SHA1 auth)"""
+
+    pg0 = None
+    vpp_clock_offset = None
+    vpp_session = None
+    test_session = None
 
     @classmethod
     def setUpClass(cls):
         super(BFDSHA1TestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
         try:
             cls.create_pg_interfaces([0])
             cls.pg0.config_ip4()
@@ -791,103 +2215,129 @@ class BFDSHA1TestCase(VppTestCase, BFDCommonCode):
             super(BFDSHA1TestCase, cls).tearDownClass()
             raise
 
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDSHA1TestCase, cls).tearDownClass()
+
     def setUp(self):
         super(BFDSHA1TestCase, self).setUp()
         self.factory = AuthKeyFactory()
         self.vapi.want_bfd_events()
-        self.pg_enable_capture([self.pg0])
+        self.pg0.enable_capture()
 
     def tearDown(self):
-        BFDCommonCode.tearDown(self)
-        VppTestCase.tearDown(self)
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=False)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFDSHA1TestCase, self).tearDown()
 
     def test_session_up(self):
-        """ bring BFD session up """
+        """bring BFD session up"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4,
-                                            sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
         self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
 
     def test_hold_up(self):
-        """ hold BFD session up """
+        """hold BFD session up"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4,
-                                            sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
         self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
 
     def test_hold_up_meticulous(self):
-        """ hold BFD session up - meticulous auth """
-        key = self.factory.create_random_key(
-            self, BFDAuthType.meticulous_keyed_sha1)
+        """hold BFD session up - meticulous auth"""
+        key = self.factory.create_random_key(self, BFDAuthType.meticulous_keyed_sha1)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
         self.vpp_session.admin_up()
+        # specify sequence number so that it wraps
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+            our_seq_number=0xFFFFFFFF - 4,
+        )
+        bfd_session_up(self)
+        for dummy in range(30):
+            wait_for_bfd_packet(self)
             self.test_session.inc_seq_num()
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
 
     def test_send_bad_seq_number(self):
-        """ session is not kept alive by msgs with bad seq numbers"""
-        key = self.factory.create_random_key(
-            self, BFDAuthType.meticulous_keyed_sha1)
+        """session is not kept alive by msgs with bad sequence numbers"""
+        key = self.factory.create_random_key(self, BFDAuthType.meticulous_keyed_sha1)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        self.wait_for_bfd_packet()
-        self.test_session.send_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        self.wait_for_bfd_packet()
-        self.test_session.send_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        self.wait_for_bfd_packet()
-        self.test_session.send_packet()
-        self.wait_for_bfd_packet()
-        self.test_session.send_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        send_until = time.time() + 2 * detection_time
+        while time.time() < send_until:
+            self.test_session.send_packet()
+            self.sleep(
+                0.7 * self.vpp_session.required_min_rx / USEC_IN_SEC,
+                "time between bfd packets",
+            )
         e = self.vapi.collect_events()
         # session should be down now, because the sequence numbers weren't
         # updated
         self.assert_equal(len(e), 1, "number of bfd events")
-        self.verify_event(e[0], expected_state=BFDState.down)
+        verify_event(self, e[0], expected_state=BFDState.down)
 
-    def execute_rogue_session_scenario(self, vpp_bfd_udp_session,
-                                       legitimate_test_session,
-                                       rogue_test_session,
-                                       rogue_bfd_values=None):
-        """ execute a rogue session interaction scenario
+    def execute_rogue_session_scenario(
+        self,
+        vpp_bfd_udp_session,
+        legitimate_test_session,
+        rogue_test_session,
+        rogue_bfd_values=None,
+    ):
+        """execute a rogue session interaction scenario
 
         1. create vpp session, add config
         2. bring the legitimate session up
@@ -900,108 +2350,132 @@ class BFDSHA1TestCase(VppTestCase, BFDCommonCode):
 
         self.vpp_session = vpp_bfd_udp_session
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = legitimate_test_session
         # bring vpp session up
-        self.bfd_session_up()
+        bfd_session_up(self)
         # send packet from rogue session
-        rogue_test_session.bfd_values = self.test_session.bfd_values.copy()
+        rogue_test_session.update(
+            my_discriminator=self.test_session.my_discriminator,
+            your_discriminator=self.test_session.your_discriminator,
+            desired_min_tx=self.test_session.desired_min_tx,
+            required_min_rx=self.test_session.required_min_rx,
+            detect_mult=self.test_session.detect_mult,
+            diag=self.test_session.diag,
+            state=self.test_session.state,
+            auth_type=self.test_session.auth_type,
+        )
         if rogue_bfd_values:
             rogue_test_session.update(**rogue_bfd_values)
         rogue_test_session.update(state=BFDState.down)
         rogue_test_session.send_packet()
-        self.wait_for_bfd_packet()
+        wait_for_bfd_packet(self)
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
 
     def test_mismatch_auth(self):
-        """ session is not brought down by unauthenticated msg """
+        """session is not brought down by unauthenticated msg"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
         vpp_session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         legitimate_test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=vpp_session.bfd_key_id)
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=vpp_session.bfd_key_id
+        )
         rogue_test_session = BFDTestSession(self, self.pg0, AF_INET)
-        self.execute_rogue_session_scenario(vpp_session,
-                                            legitimate_test_session,
-                                            rogue_test_session)
+        self.execute_rogue_session_scenario(
+            vpp_session, legitimate_test_session, rogue_test_session
+        )
 
     def test_mismatch_bfd_key_id(self):
-        """ session is not brought down by msg with non-existent key-id """
+        """session is not brought down by msg with non-existent key-id"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
         vpp_session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         # pick a different random bfd key id
         x = randint(0, 255)
         while x == vpp_session.bfd_key_id:
             x = randint(0, 255)
         legitimate_test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=vpp_session.bfd_key_id)
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=vpp_session.bfd_key_id
+        )
         rogue_test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=x)
-        self.execute_rogue_session_scenario(vpp_session,
-                                            legitimate_test_session,
-                                            rogue_test_session)
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=x
+        )
+        self.execute_rogue_session_scenario(
+            vpp_session, legitimate_test_session, rogue_test_session
+        )
 
     def test_mismatched_auth_type(self):
-        """ session is not brought down by msg with wrong auth type """
+        """session is not brought down by msg with wrong auth type"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
         vpp_session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         legitimate_test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=vpp_session.bfd_key_id)
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=vpp_session.bfd_key_id
+        )
         rogue_test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=vpp_session.bfd_key_id)
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=vpp_session.bfd_key_id
+        )
         self.execute_rogue_session_scenario(
-            vpp_session, legitimate_test_session, rogue_test_session,
-            {'auth_type': BFDAuthType.keyed_md5})
+            vpp_session,
+            legitimate_test_session,
+            rogue_test_session,
+            {"auth_type": BFDAuthType.keyed_md5},
+        )
 
     def test_restart(self):
-        """ simulate remote peer restart and resynchronization """
-        key = self.factory.create_random_key(
-            self, BFDAuthType.meticulous_keyed_sha1)
+        """simulate remote peer restart and resynchronization"""
+        key = self.factory.create_random_key(self, BFDAuthType.meticulous_keyed_sha1)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id, our_seq_number=0)
-        self.bfd_session_up()
-        # now we need to not respond for 2*detection_time (4 packets)
-        self.wait_for_bfd_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        self.wait_for_bfd_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
-        self.verify_event(e, expected_state=BFDState.down)
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+            our_seq_number=0,
+        )
+        bfd_session_up(self)
+        # don't send any packets for 2*detection_time
+        detection_time = (
+            self.test_session.detect_mult
+            * self.vpp_session.required_min_rx
+            / USEC_IN_SEC
+        )
+        self.sleep(2 * detection_time, "simulating peer restart")
+        events = self.vapi.collect_events()
+        self.assert_equal(len(events), 1, "number of bfd events")
+        verify_event(self, events[0], expected_state=BFDState.down)
         self.test_session.update(state=BFDState.down)
-        self.wait_for_bfd_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
-        self.wait_for_bfd_packet()
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
         # reset sequence number
         self.test_session.our_seq_number = 0
-        self.bfd_session_up()
+        self.test_session.vpp_seq_number = None
+        # now throw away any pending packets
+        self.pg0.enable_capture()
+        self.test_session.my_discriminator = 0
+        bfd_session_up(self)
+
 
+@tag_run_solo
+class BFDAuthOnOffTestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (changing auth)"""
 
-class BFDAuthOnOffTestCase(VppTestCase, BFDCommonCode):
-    """Bidirectional Forwarding Detection (BFD) (changing auth) """
+    pg0 = None
+    vpp_session = None
+    test_session = None
 
     @classmethod
     def setUpClass(cls):
         super(BFDAuthOnOffTestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
         try:
             cls.create_pg_interfaces([0])
             cls.pg0.config_ip4()
@@ -1012,176 +2486,751 @@ class BFDAuthOnOffTestCase(VppTestCase, BFDCommonCode):
             super(BFDAuthOnOffTestCase, cls).tearDownClass()
             raise
 
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDAuthOnOffTestCase, cls).tearDownClass()
+
     def setUp(self):
         super(BFDAuthOnOffTestCase, self).setUp()
         self.factory = AuthKeyFactory()
         self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
 
     def tearDown(self):
-        BFDCommonCode.tearDown(self)
-        VppTestCase.tearDown(self)
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=False)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFDAuthOnOffTestCase, self).tearDown()
 
     def test_auth_on_immediate(self):
-        """ turn auth on without disturbing session state (immediate) """
+        """turn auth on without disturbing session state (immediate)"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4)
+        self.vpp_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(self, self.pg0, AF_INET)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.vpp_session.activate_auth(key)
         self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
         self.test_session.sha1_key = key
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_auth_off_immediate(self):
-        """ turn auth off without disturbing session state (immediate) """
+        """turn auth off without disturbing session state (immediate)"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
+        # self.vapi.want_bfd_events(enable_disable=0)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.inc_seq_num()
             self.test_session.send_packet()
         self.vpp_session.deactivate_auth()
         self.test_session.bfd_key_id = None
         self.test_session.sha1_key = None
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.inc_seq_num()
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_auth_change_key_immediate(self):
-        """ change auth key without disturbing session state (immediate) """
+        """change auth key without disturbing session state (immediate)"""
         key1 = self.factory.create_random_key(self)
         key1.add_vpp_config()
         key2 = self.factory.create_random_key(self)
         key2.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key1)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key1
+        )
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key1,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key1,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.vpp_session.activate_auth(key2)
         self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
         self.test_session.sha1_key = key2
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_auth_on_delayed(self):
-        """ turn auth on without disturbing session state (delayed) """
+        """turn auth on without disturbing session state (delayed)"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4)
+        self.vpp_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(self, self.pg0, AF_INET)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
             self.test_session.send_packet()
         self.vpp_session.activate_auth(key, delayed=True)
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
         self.test_session.sha1_key = key
         self.test_session.send_packet()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_auth_off_delayed(self):
-        """ turn auth off without disturbing session state (delayed) """
+        """turn auth off without disturbing session state (delayed)"""
         key = self.factory.create_random_key(self)
         key.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
         self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.vpp_session.deactivate_auth(delayed=True)
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.test_session.bfd_key_id = None
         self.test_session.sha1_key = None
         self.test_session.send_packet()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
 
     def test_auth_change_key_delayed(self):
-        """ change auth key without disturbing session state (delayed) """
+        """change auth key without disturbing session state (delayed)"""
         key1 = self.factory.create_random_key(self)
         key1.add_vpp_config()
         key2 = self.factory.create_random_key(self)
         key2.add_vpp_config()
-        self.vpp_session = VppBFDUDPSession(self, self.pg0,
-                                            self.pg0.remote_ip4, sha1_key=key1)
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key1
+        )
         self.vpp_session.add_vpp_config()
         self.vpp_session.admin_up()
         self.test_session = BFDTestSession(
-            self, self.pg0, AF_INET, sha1_key=key1,
-            bfd_key_id=self.vpp_session.bfd_key_id)
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+            self,
+            self.pg0,
+            AF_INET,
+            sha1_key=key1,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+        )
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.vpp_session.activate_auth(key2, delayed=True)
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
         self.test_session.sha1_key = key2
         self.test_session.send_packet()
-        for i in range(5):
-            self.wait_for_bfd_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
             self.test_session.send_packet()
         self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
-        self.assert_equal(len(self.vapi.collect_events()), 0,
-                          "number of bfd events")
+        self.assert_equal(len(self.vapi.collect_events()), 0, "number of bfd events")
+
+
+@tag_run_solo
+class BFDCLITestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (CLI)"""
+
+    pg0 = None
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDCLITestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces((0,))
+            cls.pg0.config_ip4()
+            cls.pg0.config_ip6()
+            cls.pg0.resolve_arp()
+            cls.pg0.resolve_ndp()
+
+        except Exception:
+            super(BFDCLITestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDCLITestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDCLITestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.pg0.enable_capture()
+
+    def tearDown(self):
+        try:
+            self.vapi.want_bfd_events(enable_disable=False)
+        except UnexpectedApiReturnValueError:
+            # some tests aren't subscribed, so this is not an issue
+            pass
+        self.vapi.collect_events()  # clear the event queue
+        super(BFDCLITestCase, self).tearDown()
 
-if __name__ == '__main__':
+    def cli_verify_no_response(self, cli):
+        """execute a CLI, asserting that the response is empty"""
+        self.assert_equal(self.vapi.cli(cli), "", "CLI command response")
+
+    def cli_verify_response(self, cli, expected):
+        """execute a CLI, asserting that the response matches expectation"""
+        try:
+            reply = self.vapi.cli(cli)
+        except CliFailedCommandError as cli_error:
+            reply = str(cli_error)
+        self.assert_equal(reply.strip(), expected, "CLI command response")
+
+    def test_show(self):
+        """show commands"""
+        k1 = self.factory.create_random_key(self)
+        k1.add_vpp_config()
+        k2 = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1
+        )
+        k2.add_vpp_config()
+        s1 = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        s1.add_vpp_config()
+        s2 = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6, sha1_key=k2
+        )
+        s2.add_vpp_config()
+        self.logger.info(self.vapi.ppcli("show bfd keys"))
+        self.logger.info(self.vapi.ppcli("show bfd sessions"))
+        self.logger.info(self.vapi.ppcli("show bfd"))
+
+    def test_set_del_sha1_key(self):
+        """set/delete SHA1 auth key"""
+        k = self.factory.create_random_key(self)
+        self.registry.register(k, self.logger)
+        self.cli_verify_no_response(
+            "bfd key set conf-key-id %s type keyed-sha1 secret %s"
+            % (
+                k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k.key),
+            )
+        )
+        self.assertTrue(k.query_vpp_config())
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=k
+        )
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=k, bfd_key_id=self.vpp_session.bfd_key_id
+        )
+        self.vapi.want_bfd_events()
+        bfd_session_up(self)
+        bfd_session_down(self)
+        # try to replace the secret for the key - should fail because the key
+        # is in-use
+        k2 = self.factory.create_random_key(self)
+        self.cli_verify_response(
+            "bfd key set conf-key-id %s type keyed-sha1 secret %s"
+            % (
+                k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k2.key),
+            ),
+            "bfd key set: `bfd_auth_set_key' API call failed, "
+            "rv=-103:BFD object in use",
+        )
+        # manipulating the session using old secret should still work
+        bfd_session_up(self)
+        bfd_session_down(self)
+        self.vpp_session.remove_vpp_config()
+        self.cli_verify_no_response("bfd key del conf-key-id %s" % k.conf_key_id)
+        self.assertFalse(k.query_vpp_config())
+
+    def test_set_del_meticulous_sha1_key(self):
+        """set/delete meticulous SHA1 auth key"""
+        k = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1
+        )
+        self.registry.register(k, self.logger)
+        self.cli_verify_no_response(
+            "bfd key set conf-key-id %s type meticulous-keyed-sha1 secret %s"
+            % (
+                k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k.key),
+            )
+        )
+        self.assertTrue(k.query_vpp_config())
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6, sha1_key=k
+        )
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET6, sha1_key=k, bfd_key_id=self.vpp_session.bfd_key_id
+        )
+        self.vapi.want_bfd_events()
+        bfd_session_up(self)
+        bfd_session_down(self)
+        # try to replace the secret for the key - should fail because the key
+        # is in-use
+        k2 = self.factory.create_random_key(self)
+        self.cli_verify_response(
+            "bfd key set conf-key-id %s type keyed-sha1 secret %s"
+            % (
+                k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k2.key),
+            ),
+            "bfd key set: `bfd_auth_set_key' API call failed, "
+            "rv=-103:BFD object in use",
+        )
+        # manipulating the session using old secret should still work
+        bfd_session_up(self)
+        bfd_session_down(self)
+        self.vpp_session.remove_vpp_config()
+        self.cli_verify_no_response("bfd key del conf-key-id %s" % k.conf_key_id)
+        self.assertFalse(k.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp(self):
+        """create/modify/delete IPv4 BFD UDP session"""
+        vpp_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = (
+            "bfd udp session add interface %s local-addr %s "
+            "peer-addr %s desired-min-tx %s required-min-rx %s "
+            "detect-mult %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip4,
+                self.pg0.remote_ip4,
+                vpp_session.desired_min_tx,
+                vpp_session.required_min_rx,
+                vpp_session.detect_mult,
+            )
+        )
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object",
+        )
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self,
+            self.pg0,
+            self.pg0.remote_ip4,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult,
+        )
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip4,
+                self.pg0.remote_ip4,
+                mod_session.desired_min_tx,
+                mod_session.required_min_rx,
+                mod_session.detect_mult,
+            )
+        )
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = (
+            "bfd udp session del interface %s local-addr %s "
+            "peer-addr %s" % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        )
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object",
+        )
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp6(self):
+        """create/modify/delete IPv6 BFD UDP session"""
+        vpp_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip6, af=AF_INET6)
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = (
+            "bfd udp session add interface %s local-addr %s "
+            "peer-addr %s desired-min-tx %s required-min-rx %s "
+            "detect-mult %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip6,
+                self.pg0.remote_ip6,
+                vpp_session.desired_min_tx,
+                vpp_session.required_min_rx,
+                vpp_session.detect_mult,
+            )
+        )
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object",
+        )
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self,
+            self.pg0,
+            self.pg0.remote_ip6,
+            af=AF_INET6,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult,
+        )
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip6,
+                self.pg0.remote_ip6,
+                mod_session.desired_min_tx,
+                mod_session.required_min_rx,
+                mod_session.detect_mult,
+            )
+        )
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = (
+            "bfd udp session del interface %s local-addr %s "
+            "peer-addr %s" % (self.pg0.name, self.pg0.local_ip6, self.pg0.remote_ip6)
+        )
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object",
+        )
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp_auth(self):
+        """create/modify/delete IPv4 BFD UDP session (authenticated)"""
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = (
+            "bfd udp session add interface %s local-addr %s "
+            "peer-addr %s desired-min-tx %s required-min-rx %s "
+            "detect-mult %s conf-key-id %s bfd-key-id %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip4,
+                self.pg0.remote_ip4,
+                vpp_session.desired_min_tx,
+                vpp_session.required_min_rx,
+                vpp_session.detect_mult,
+                key.conf_key_id,
+                vpp_session.bfd_key_id,
+            )
+        )
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object",
+        )
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self,
+            self.pg0,
+            self.pg0.remote_ip4,
+            sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult,
+        )
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip4,
+                self.pg0.remote_ip4,
+                mod_session.desired_min_tx,
+                mod_session.required_min_rx,
+                mod_session.detect_mult,
+            )
+        )
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = (
+            "bfd udp session del interface %s local-addr %s "
+            "peer-addr %s" % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        )
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object",
+        )
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp6_auth(self):
+        """create/modify/delete IPv6 BFD UDP session (authenticated)"""
+        key = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1
+        )
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6, sha1_key=key
+        )
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = (
+            "bfd udp session add interface %s local-addr %s "
+            "peer-addr %s desired-min-tx %s required-min-rx %s "
+            "detect-mult %s conf-key-id %s bfd-key-id %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip6,
+                self.pg0.remote_ip6,
+                vpp_session.desired_min_tx,
+                vpp_session.required_min_rx,
+                vpp_session.detect_mult,
+                key.conf_key_id,
+                vpp_session.bfd_key_id,
+            )
+        )
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object",
+        )
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self,
+            self.pg0,
+            self.pg0.remote_ip6,
+            af=AF_INET6,
+            sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult,
+        )
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip6,
+                self.pg0.remote_ip6,
+                mod_session.desired_min_tx,
+                mod_session.required_min_rx,
+                mod_session.detect_mult,
+            )
+        )
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = (
+            "bfd udp session del interface %s local-addr %s "
+            "peer-addr %s" % (self.pg0.name, self.pg0.local_ip6, self.pg0.remote_ip6)
+        )
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object",
+        )
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_auth_on_off(self):
+        """turn authentication on and off"""
+        key = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1
+        )
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        auth_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
+        session.add_vpp_config()
+        cli_activate = (
+            "bfd udp session auth activate interface %s local-addr %s "
+            "peer-addr %s conf-key-id %s bfd-key-id %s"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip4,
+                self.pg0.remote_ip4,
+                key.conf_key_id,
+                auth_session.bfd_key_id,
+            )
+        )
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        cli_deactivate = (
+            "bfd udp session auth deactivate interface %s local-addr %s "
+            "peer-addr %s " % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        )
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+
+    def test_auth_on_off_delayed(self):
+        """turn authentication on and off (delayed)"""
+        key = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1
+        )
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        auth_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key
+        )
+        session.add_vpp_config()
+        cli_activate = (
+            "bfd udp session auth activate interface %s local-addr %s "
+            "peer-addr %s conf-key-id %s bfd-key-id %s delayed yes"
+            % (
+                self.pg0.name,
+                self.pg0.local_ip4,
+                self.pg0.remote_ip4,
+                key.conf_key_id,
+                auth_session.bfd_key_id,
+            )
+        )
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        cli_deactivate = (
+            "bfd udp session auth deactivate interface %s local-addr %s "
+            "peer-addr %s delayed yes"
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        )
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+
+    def test_admin_up_down(self):
+        """put session admin-up and admin-down"""
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        cli_down = (
+            "bfd udp session set-flags admin down interface %s local-addr %s "
+            "peer-addr %s " % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        )
+        cli_up = (
+            "bfd udp session set-flags admin up interface %s local-addr %s "
+            "peer-addr %s " % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        )
+        self.cli_verify_no_response(cli_down)
+        verify_bfd_session_config(self, session, state=BFDState.admin_down)
+        self.cli_verify_no_response(cli_up)
+        verify_bfd_session_config(self, session, state=BFDState.down)
+
+    def test_set_del_udp_echo_source(self):
+        """set/del udp echo source"""
+        self.create_loopback_interfaces(1)
+        self.loopback0 = self.lo_interfaces[0]
+        self.loopback0.admin_up()
+        self.cli_verify_response("show bfd echo-source", "UDP echo source is not set.")
+        cli_set = "bfd udp echo-source set interface %s" % self.loopback0.name
+        self.cli_verify_no_response(cli_set)
+        self.cli_verify_response(
+            "show bfd echo-source",
+            "UDP echo source is: %s\n"
+            "IPv4 address usable as echo source: none\n"
+            "IPv6 address usable as echo source: none" % self.loopback0.name,
+        )
+        self.loopback0.config_ip4()
+        echo_ip4 = str(
+            ipaddress.IPv4Address(
+                int(ipaddress.IPv4Address(self.loopback0.local_ip4)) ^ 1
+            )
+        )
+        self.cli_verify_response(
+            "show bfd echo-source",
+            "UDP echo source is: %s\n"
+            "IPv4 address usable as echo source: %s\n"
+            "IPv6 address usable as echo source: none"
+            % (self.loopback0.name, echo_ip4),
+        )
+        echo_ip6 = str(
+            ipaddress.IPv6Address(
+                int(ipaddress.IPv6Address(self.loopback0.local_ip6)) ^ 1
+            )
+        )
+        self.loopback0.config_ip6()
+        self.cli_verify_response(
+            "show bfd echo-source",
+            "UDP echo source is: %s\n"
+            "IPv4 address usable as echo source: %s\n"
+            "IPv6 address usable as echo source: %s"
+            % (self.loopback0.name, echo_ip4, echo_ip6),
+        )
+        cli_del = "bfd udp echo-source del"
+        self.cli_verify_no_response(cli_del)
+        self.cli_verify_response("show bfd echo-source", "UDP echo source is not set.")
+
+
+if __name__ == "__main__":
     unittest.main(testRunner=VppTestRunner)