Packet tracer activity

nnbnbOk. My tutor gave me a packet tracer activity and i having some troubles resolving some issues. Here is the basic topology.

img142.imagevenue.com/img.php?image=9875...pology_122_383lo.JPG


My FastEthernet interfaces are working for each router, as the PC can ping the router. Now the problem is created when i wanted to configure the IP for the serial links. Whenever i try to put in the serial IP address e.g. 172.20.4.1 in the CLI of Router0, the message i get is the 172.20.0.0 overlaps with Serial0/1/0. So i can't configure any of serial links, how could i resolve this issue.

Whats the subnet mask on the fast ethernet interfaces ? Sounds like you have set a class b 255.255.0.0 which will cause an overlapping addresss. TRy setting it to 255.255.255.0 throughout.

Thanks for the suggestion, but my tutor said to use 255.255.0.0, what should i do? By the way i tried it and it still doesn't work

Thanks for the suggestion, but my tutor said to use 255.255.0.0, what should i do? By the way i tried it and it still doesn't work

As smurf pointed out, you should change it to 255.255.255.0. But make sure you do that on all interfaces that are part of the 172.20.x.x range on all routers. I can't think of an other reason for the overlapping problem other than this.

Sorry, i was a bit vague, yea all the lights have turned green, i m sure all of us can picture that, but what i meant by not working was, the topology is not working. I sent a ping from PC0 to PC2 and it failed. I tried the tracert command and from the looks of it the router doesn't know where to forward the packet. So the problem must be rip, i put in all the networks and for some reason all i get is 172.20.0.0, even though i added all the network throughout 1.0 to 6.0 on all routers. I checked the routing tables and there is no rip only connected.
I tried removing the 172.20.0.0 (no network 172.20.0.0) but still doesnt work. What should i do?

Do you still get the error message:

"the 172.20.0.0 overlaps with Serial0/1/0"

If you do then, you have to use 255.255.255.0 on all interfaces in 172.20.x.x.

After that, for routing to work, Use RIP version 2 on all routers:

[code:1]Router(config-router)#version 2[/code:1]

RIP version 1 can't work with 255.255.255.0 on the 172.20.x.x range since RIPv1 is classfull and will assume 255.255.0.0 with the 172.20.x.x.