1. Goal

We're introducing anycast as mechanism to increase the availability of a server, in this case a DNS server. We're interested in seeing anycast workin and at the moment we're not so much interested in which routing protocol is being used. We'll use RIP because it is easy. We're also not so much interested in security (at first at least), so forget the enable password, the banner and ssh for the moment. Also, we're using /24 networks for simplification so I don't have to calculate netmasks.

1.1. Network layout

Two data centres are connected through an ethernet-like interface (I don't need the trouble of a serial link in this lab). Both data centres have a DNS server (xenial1 and xenial2) and both have a DNS client (xenial3 and xenial4). Between the datacentres there are routers, and the DNS server is behind a second router.

1.2. Steps

We'll go through the configuration in different steps:
  • set-up the network in GNS3
  • set-up the DNS-servers on the Debian
  • verify that it works with unicast DNS calls
  • set-up any-cast

1.3. Versions

february 2016
based on debian
april 2018
introduced vagrant; precise server and fedora clients
february 2020
all machines to xenial; no more tap-devices (all vboxnet)