Behavior of RIPv2

limtohsoon · ‎03-03-2007

Hi Sir,

I found the following technote:

Behavior of RIP and IGRP When Sending and Receiving Updates:

http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a0080093fd8.shtml

I suppose it is referring to the operation of RIPv1.

Suppose, I configure a router to run RIPv2 as follows:

!

router rip

version 2

network 10.0.0.0

auto-summary

!

With the "auto-summary" keyword, is it going to behave as per the technote above? With "no auto-summary", how is it going to behave?

Please advise.

Thank you.

B.Rgds,

Lim TS

Richard Burts · ‎03-03-2007

Lim

You are correct that it is describing the operation of RIPv1. Even with the auto-summary keyword some of the behaviors will be different. In particular RIPv1 will not advertise a subnet out another interface (in the same major network) if the subnet mask is different and RIPv2 will advertise the subnet. An example may help clarify. Assume the router has Ethernet 0 with ip address 10.1.1.1 255.255.255.0 and has Serial0 with ip address 10.1.2.1 255.255.255.252. RIPv1 will not advertise the serial subnet out the ethernet interface and not advertise the ethernet subnet out the serial interface. RIPv2 will advertise those subnets out the interfaces.

To extend the example a little: assume that the router also has Ethernet 1 with ip address 172.16.1.1 255.255.255.0. With auto-summary both RIPv1 and RIPv2 would advertise 10.0.0.0/8 out Ethernet 1. But with no auto-summary RIPv2 would advertise 10.1.1.0/24 and 10.1.2.0/30 out Ethernet 1.

HTH

Rick

HTH

Rick