ISDN backup link configuration and EIGRP redistribution - Part 2

While, route of backup link has been redistributed secussfully. Let's bring it on and see what will happen!

I pinged the fake ip address and debug message showed the backup link is on, oh wait a minute, the router 2 established neighbour adjacency with south router. I had feeling that something would be wrong.

Yes, the core switch rebooted! I believe it was caused by routing loop.

The more detailed network topology should be something like this:





So you can see the route loop was created if the backup link was brought up.

It is all the fault by ISP's BGP redistribution settings. They did it without routing filtering!

So the only solution is to configure passive interface:

router eigrp xx
passive-interface bri1/3

Now it is all done.