+
+Systemd configuration
+---------------------
+
+In a typical home-gateway use-case, vpp owns the one-and-only WAN link
+with a prayer of reaching the public internet. Simple things like
+updating distro software requires use of the "lstack" interface
+created above, and configuring a plausible upstream DNS name resolver.
+
+Configure /etc/systemd/resolved.conf as follows.
+
+/etc/systemd/resolved.conf::
+
+ [Resolve]
+ DNS=8.8.8.8
+ #FallbackDNS=
+ #Domains=
+ #LLMNR=no
+ #MulticastDNS=no
+ #DNSSEC=no
+ #Cache=yes
+ #DNSStubListener=yes
+
+Netplan configuration
+---------------------
+
+If you want to configure a static IP address on one of your
+home-gateway Ethernet ports on Ubuntu 18.04, you'll need to configure
+netplan. Netplan is relatively new. It and the network manager GUI and
+can be cranky. In the configuration shown below,
+s/enp4s0/<your-interface>/...
+
+/etc/netplan-01-netcfg.yaml::
+
+ # This file describes the network interfaces available on your system
+ # For more information, see netplan(5).
+ network:
+ version: 2
+ renderer: networkd
+ ethernets:
+ enp4s0:
+ dhcp4: no
+ addresses: [192.168.2.254/24]
+ gateway4: 192.168.2.100
+ nameservers:
+ search: [my.local]
+ addresses: [8.8.8.8]
+
+/etc/systemd/network-10.enp4s0.network::
+
+ [Match]
+ Name=enp4s0
+
+ [Link]
+ RequiredForOnline=no
+
+ [Network]
+ ConfigureWithoutCarrier=true
+ Address=192.168.2.254/24
+
+Note that we've picked an IP address for the home gateway which is on
+an independent unrouteable subnet. This is handy for installing (and
+possibly reverting) new vpp software.
+
+Installing new vpp software
+---------------------------
+
+If you're **sure** that a given set of vpp Debian packages will
+install and work properly, you can install them while logged into the
+gateway via the lstack / nat path. This procedure is a bit like
+standing on a rug and yanking it. If all goes well, a perfect
+back-flip occurs. If not, you may wish that you'd configured a static
+IP address on a reserved Ethernet interface as described above.
+
+Installing a new vpp image via ssh to 192.168.1.2::
+
+ # nohup dpkg -i *.deb >/dev/null 2>&1 &
+
+Within a few seconds, the inbound ssh connection SHOULD begin to respond
+again. If it does not, you'll have to debug the issue(s).
+
+Testing new software
+--------------------
+
+If you frequently test new home gateway software, it may be handy to
+set up a test gateway behind your production gateway. This testing
+methodology reduces complaints from family members, to name one benefit.
+
+Change the inside network (dhcp) subnet from 192.168.1.0/24 to
+192.168.3.0/24, change the (dhcp) advertised router to 192.168.3.1,
+reconfigure the vpp tap interface addresses onto the 192.168.3.0/24
+subnet, and you should be all set.
+
+This scenario nats traffic twice: first, from the 192.168.3.0/24
+network onto the 192.168.1.0/24 network. Next, from the 192.168.1.0/24
+network onto the public internet.
+