Router rip

[Blackinc]

 I am new to Cisco and I have an issue with my rip configuration. I did rip configuration on router giving the network 10.0.0.0  I erased the memory and reloaded the router for some reason. Now when I configured the rip network giving 10.254.10.0 it still showing the old network id 10.0.0.0 in the router rip when I check using show run command. I tried changing the network several times but nothing worked  How to fix this?

[M02@rt37]

Hello @Blackinc,

RIP is indeed a classful routing protocol, which means it doesn't support subnet masks in its routing updates. It relies on classful network boundaries, such as Class A, B, or C networks. This could explain the behavior you're seeing.

If you initially configured RIP with a network statement like 'network 10.0.0.0'  it implies that you want to advertise all Class A networks (10.0.0.0 to 10.255.255.255). When you later try to configure a more specific network like 10.254.10.0, RIP might still treat it as part of the broader Class A network because of its classful nature.

[Blackinc]

Is there a way to fix the problem? I am a complete beginner. can you mention the steps to fix it?

[M02@rt37]

@Blackinc 

Jump to RIP version 2.

Although RIP v2 is classless,  configuration of which interfaces are attached to the RIP process is classfull...

You always see 10.0.0.0 in your show run but the mask should be carried through advertisements update. Means that in the other side network 10.254.10.0/24 is annonced via RIP.

[Martin L]

You must use version 2 of RIP; just update your current config using version 2 command. This makes RIP classful to behave like classless where advertisements now will carry mask in its update packets.  This update does not completely removes classful behavior. Entering network 10.0.0.0 will enable RIP advertisements on all interfaces falling into that class network and no auto-summary should be use on all RIP routers. By default, RIP will auto-summary all networks based on their class. Note that RIP configuration is no longer on any exams; only distance-vector theory is.

Regards, ML
**Please Rate All Helpful Responses **

[Blackinc]

I already configured using rip version 2.

What are the step to change the network to 10.254.10.0

[Martin L]

I configured the rip network giving 10.254.10.0 it still showing the old network id 10.0.0.0 in the router rip when I check using show run command

There is NO way to fix it!  this is how RIP works; it has not been upgraded as EIGRP was; If you enter network 172.16.11.0 and

network 172.16.11.4,  you will get network 172.16.0.0 under router rip; Similarly, if u enter network 192.168.10.4, u get

network 192.168.10.0.  However, if u using version 2, you will have correct networks and their masks being advertised to other RIP routers. If u not seeing correct network and mask in routing table, you have msiconfigured mask on interface, or have  summary enabled, or version 1 of RIP running.

Another point is about network command itself.  The purpose of network command under router rip (or any other IGP protocols) is often misunderstood.  network x.x.x.x command under router xyz does not actually advertise network x.x.x.x; this command tells routing process to 1. look at all its connected interfaces that are up up state and fall into the range of x.x.x.x and 2. start sending advertisements out of those interfaces. 3. accept advertisements send by others and exchange routes.

Regards, ML
**Please Rate All Helpful Responses **

[Joseph W. Doherty]

I recall (???) RIPv2 is a bit "quirky", in that you might still use classful network statements, but v2 does carry subnets.

If you have a copy of PT, you might open the attachment.

[Joseph W. Doherty]

M02@rt37 and @Martin L replies, after my prior reply, both much better describe what I meant by "quirky" regarding RIPv2's network statement; and the behavior they described can be seen in the PT file I provided.  What I also want to emphasize is the significance of this behavior.

As the network statement matches interfaces IP addresses using Classful rules, you cannot get, for example, 10.0.1.0/24 in RIPv2 while not getting 10.0.2.0/24.  I.e. any interface IP address that's a "subnet" of the network statement's Class IP will be matched.

Although the network statement for RIP v1 or v2 will appear the same and match interfaces the same, what's advertised may NOT be the same.

For interfaces 10.0.1.0/24 and 10.0.2.0/24, you'll see those in the v2 route tables, but in v1 you would only see 10.0.0.0/8.