Prakash

I do not fully understand your explanation of the topology and perhaps do not fully understand your question. But I believe that the answer you are looking for is that unless you are going to do something in RIP like redistribute connected, then there must be network statements under router rip that include both the interface(s) that rip will advertise over and also network statements that include the segments where end user stations are located that you want to advertise. So in your case it is the IP of both the serial and the etheret ports.

HTH

Rick