IPv4 routes via IPv6 next hop NLRI

This example configures an IPv4 route with a next hop which only has an IPv6 address:

  • define a virtual interface loopback with IPv4 and IPv6 addresses
  • configure a physical interface eth0 with an IPv6 address
  • add default IPv4 and IPv6 routes via an IPv6 link-local next hop on eth0
interfaces:
  loopback:
    addresses:
    - 2001:db8::42/128
    - 192.0.2.42/32
    link:
      state: up
      kind: dummy
  eth0:
    addresses:
      - 2001:db8:0:1000::2/64
    link:
      kind: physical
      state: up
routing:
  routes:
    - to: 0.0.0.0/0
      via: fe80::defa
      dev: eth0
    - to: ::/0
      via: fe80::defa
      dev: eth0

{
  networking.ifstate = {
    enable = true;
    settings = {
      interfaces = {
        loopback = {
          addresses = [ "2001:db8::42/128" "192.0.2.42/32" ];
          link = {
            state = "up";
            kind = "dummy";
          };
        };
        eth0 = {
          addresses = [ "2001:db8:0:1000::2/64" ];
          link = {
            kind = "physical";
            state = "up";
          };
        };
      };
      routing = {
        routes = [
          {
            to = "0.0.0.0/0";
            via = "fe80::defa";
            dev = "eth0";
          }
          {
            to = "::/0";
            via = "fe80::defa";
            dev = "eth0";
          }
        ];
      };
    };
  };
}

# configure loopback
ip link add loopback type dummy
ip link set loopback up
ip address add 2001:db8::42/128 dev loopback
ip address add 192.0.2.42/32 dev loopback

# configure eth0
ip link dev eth0 set up
ip address add 2001:db8:0:1000::2/64 dev eth0

# configure default routes
ip route add ::/0 via fe80::defa dev eth0
ip route add 0/0 via inet6 fe80::defa dev eth0