Static routes between serial interfaces

[a.burchell]

We have 2 2611 router connected via a wic-1t.

Router A has a Fa0/0 address 172.16.100.1/16

Router A has a Ser 0/0 address of 172.220.1.1/16

Router B has a Fa0/0 address 172.18.100.1/16

Router B has a Ser 0/0 address of 172.220.1.2/16

In each router we have added a static route pointing to the remote routers serial interface ip address.

ie Router A "ip route 172.16.0.0 255.255.0.0 172.220.1.2

ie Router B "ip route 172.18.0.0 255.255.0.0 172.220.1.1

When pinging from the console port on each router I am unable to ping the fa0/0 subnet on the far

router.

However if I ping from a pc connected to the local fa0/0 i am able to the fa0/0 on the remote subnet.

Can anyone tell me why this only happens when you add a IP address to both serial interfaces.

If we configure "ip unnumbered" or use a routing protocol it works. But not with static routes.

Thanks very much.

[ehirsel]

It may have to do with how inverse arp is operating.

Please do this:

With the static routes configured, run the show ip route command on both routers and post them here.

Do the same with ip unumbered, and when you have the routing protocols established.

Also, how are the serial interfaces setup? Are you using Frame-relay, PPP, or other protocol?

[frennzy]

I think you have those static routes backwards, unless you just made a type.

Router A should have

ip route 172.18.0.0 255.255.0.0 172.220.1.2

and router B should have

ip route 172.16.0.0 255.255.0.0 172.220.1.1

Also, why are you using a 16 bit mask on a serial link? I would use a /30 or a /31

[a.burchell]

Thankyou for your reply frenzy, sorry my error i have those routes you stated, just wrote them down incorrect in the discussion

Thanks

[frennzy]

I thought that was probably the case. I had to correct my reply two or three times to get it correct. :)

Can you post the config of each router, and post the output of a 'sh ip route' from each router, as the previous person asked? (if you can, try to do so with both the working and non-working configurations).

[Richard Burts]

When you ping from the console the source address of the ping will be the address of the serial interface. When you ping from a PC on the FastEthernet the source address will be the address of the FastEthernet.

If ping works from the PC on the FastEthernet that is saying that your static routes work. When ping fails from the console it is probably indicating that it does not know a route back to your router serial interface.

I know that what you posted looked like they were both in a connected subnet. But the behavior suggests oterwise. Please check both routers and make sure that there was not a configuration error of some sort.

HTH

Rick

[ehirsel]

How is your serial interface configured? Are you using a frame-relay connection between the routers?

Please post that part of the config from both routers as well.

[a.burchell]

Hi Guys,

Thanks very much to all your responses. I have sorted out the prob. All I needed to do was to add a route to each router to tell it how to get to the remote routers ser 0/0. Simple really just could not work it out last week. Thanks again.

[ehirsel]

How did you add the static routes? Like this: route dest-net dest-wildcard-mask interface ser 0/0?