Routing the Loopback

I am installing loopback addresses on a series of switches and a few routers; using 192.168.0.x /32 on each device. I understand I need to run a routing protocol on the routers e.g. router rip network My question is - what do I need to do on the switch configuration - int loopback0 ip address

- is this enough? Thanks

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Yes, and then ensure that is advertised. The problem with this case is that you want 0.123 to be advertised as a /32, and your other networks as /24s or whatever. The point is, if you needed to turn up another router that owns, but also had a loopback of, where will the traffic go? In this example, it would go to the first router since that is advertising So in short, you should pick a loopback range that is unique from your main networks (it can be in the same overall range), but should be a special block of addresses like 0.0 - 0.255 and it should not be summarized because it is a /32 and the rest of the range will be used by other routers in the same location for their loopbacks. Your main networks should be summarized where you can. Hope this makes sense.
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Note also that RIP V1 does not support VLSM. You need to use RIP V2 (or of course somehting more modern entirely).

I don't know what you get if you don't specify the version in IOS.

sh ip protocols Routing Protocol is "rip" Default version control: send version 1, receive any version

So that's confirmed, default is version 1.

conf t router rip version 2

sh ip protocols Default version control: send version 2, receive version 2

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RIPv1 does support host routes, though, which I think it infers from non-zero bits in what it thinks is the host field. You can (IIRC) advertise /32s along with your /24s or whatever other netmask is the "correct" one for your classful network.

... as if anyone should care what a classful network is these days.


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Sam Wilson

I have hardly used RIP but I am trying to learn a bit for the exams.

I can see that that would work.

You can (IIRC)


There though are a few gottchas lurking here and there.

I have always just avoided classful routing protocols and have effectively never used them except when a provider like Bloomberg sends you some routes. I always redistribute them at the earliest opportunity.


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Yep, though we don't seem to have any left on our network (we have some RIPv1 around the edge to support some really primitive kit but they're only announcing /24s). See RFC 1058 section 3.2 if you really want to.

I'm trying to forget as much as possible! :-)

For sure.


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