EIGRP config on BRI0 disappearing after use on 1721

[johndennison]

Hello.

We've got a 1721 utilizing ISDN Dial Backup (BRI0). Here is the BRI0 config:

interface BRI0

description ISDN Dial Backup

ip address negotiated

ip nat outside

ip hello-interval eigrp 100 3

ip hold-time eigrp 100 9

encapsulation ppp

dialer map ip XX.XX.XX.XX broadcast XXXXXXXXXXX

dialer watch-group 1

isdn switch-type basic-ni

isdn spid1 XXXXXXXXXXXXXX XXXXXXXXXX

no peer default ip address

ppp ipcp mask request

ppp ipcp address accept

Everything works fine. The problem is once the dial backup is forced up and then goes down once the Frame Relay comes back the configuration lines "ip hello-interval eigrp 100 3" and "ip hold-time eigrp 100 9" disappear from the config. And next time the dial backup is forced up it's got the default EIGRP timers. Why is this happening?? Thanks.

[Richard Burts]

John

I am not sure what the official answer is, but here is my theory of the problem. When you first configure the interface it has no IP address (it is using ip address negotiated) and so it does not match any of the network statements under EIGRP and so is not an EIGRP interface. Then when you force the interface up, it does get an IP address, I assume that the address does match one of the network statements under EIGRP, so it is processed as an EIGRP interface and has the parameters that you configure for hold time and for hello interval. Then when the interface goes down the IP address is withdrawn. Now the interface is no longer an EIGRP interface. And in the process of removing the interface from EIGRP any EIGRP parameters are removed from the interface config.

It is a pretty common behavior in IOS that if you remove something from the configuration then any subsidiary (lower or dependent) commands are also removed. Most of the time the results of that are what we want and expect. In your case it is not. I am not sure that there is much that you can do about it except to perhaps open a TAC case about it.

HTH

Rick