RIPv1

[ohassairi]

                   hello

suppose we have the following diagram with ripv1 enabled

RIPv1 does not send the mask. so R2 will see in the update message a route to 192.168.1.0 that is less specific than 192.168.1.128/25

so why it will not add it to its routing table as 192.168.1.0/24 so that it will have 2 routes :

R  192.168.1.0/24   via 192.168.0.1

C  192.168.1.128/25  via e0

this will not make any confusion for R2

[siddiqirf]

No, because to get to all other ip routes/hosts that do not fall into 192.168.1.128/25 (ie. 192.168.1.1/25),  R2 will follow the 192.168.1.0/24 route across the WAN link.

[cadet alain · Accepted solution]

Hi,

When R2 receives the update it will see if it is in the same major network as the receiving interface which is not the case here( it receives a 192.168.1.0 and it is connected to 192.168.0.0) so it checks if any subnets of the received network already exist in the rib and it is the case here with 192.168.1.128/25 and so it ignores the update.

Regards.

Alain

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[ohassairi]

for more details about how rip send/receive updates:

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