RIPng
Table 10.3 lists IPv6 RIP Commands. To be honest, the primary features of RIPng are the
same as they were with RIPv2. It is still a distance-vector protocol; has a max hop count of 15;
and uses split horizon, poison reverse, and other loop avoidance mechanisms. However, it
now uses UDP port 521.
It still uses multicast to send its updates too, but in IPv6, it uses FF02::9 for the transport
address. This is actually kind of cool since in RIPv2, the multicast address was 224.0.0.9,
so the address still has a 9 at the end in the new IPv6 multicast range. In fact, most routing protocols
got to keep a little bit of their IPv4 identities like that.
But of course there are differences in the new version, or it wouldn’t be a new version,
would it? We know that routers keep the next-hop addresses of their neighbor routers for
every destination network in their routing table. The difference is that with RIPng, the router
keeps track of this next-hop address using the link-local address, not a global address.
Probably one of the biggest changes with RIPng (and all of the IPv6 routing protocols for
that matter) is that you configure or enable the advertisement of a network from interface configuration
mode instead of with a network command in router configuration mode. So in
RIPng’s case, if you enable it directly on an interface without going into router configuration
mode and starting a RIPng process, a new RIPng process will simply be started for you. It will
look something like this:
Router1(config-if)#ipv6 rip 1 enable
That 1 you see in this command is a tag that identifies the process of RIPng that’s running,
and as I said, this will start a process of RIPng so you don’t have to go into router configuration
mode.
But if you need to go to router configuration mode to configure something else like redistribution,
you still can. If you do that, it will look like this on your router:
Router1(config)#ipv6 router rip 1
Router1(config-rtr)#
So, just remember that RIPng will pretty much work the same way as with IPv4, with the
biggest difference being that it uses the network itself instead of using the network command
you used to use to enable the interface to route the connected network.