+/**
+ * Link Type: A description of the protocol of packets on the link.
+ * On an ethernet link this maps directly into the ethertype. On a GRE tunnel
+ * it maps to the GRE-proto, etc for other lnk types.
+ */
+typedef enum vnet_link_t_
+{
+#if CLIB_DEBUG > 0
+ VNET_LINK_IP4 = 1,
+#else
+ VNET_LINK_IP4 = 0,
+#endif
+ VNET_LINK_IP6,
+ VNET_LINK_MPLS,
+ VNET_LINK_ETHERNET,
+ VNET_LINK_ARP,
+} __attribute__ ((packed)) vnet_link_t;
+
+#define VNET_LINKS { \
+ [VNET_LINK_ETHERNET] = "ethernet", \
+ [VNET_LINK_IP4] = "ipv4", \
+ [VNET_LINK_IP6] = "ipv6", \
+ [VNET_LINK_MPLS] = "mpls", \
+ [VNET_LINK_ARP] = "arp", \
+}
+
+/**
+ * @brief Number of link types. Not part of the enum so it does not have to be included in
+ * switch statements
+ */
+#define VNET_LINK_NUM (VNET_LINK_ARP+1)
+
+/**
+ * @brief Convert a link to to an Ethertype
+ */
+extern vnet_l3_packet_type_t vnet_link_to_l3_proto (vnet_link_t link);
+
+/**
+ * @brief Attributes assignable to a HW interface Class.
+ */
+typedef enum vnet_hw_interface_class_flags_t_
+{
+ /**
+ * @brief a point 2 point interface
+ */
+ VNET_HW_INTERFACE_CLASS_FLAG_P2P = (1 << 0),
+} vnet_hw_interface_class_flags_t;