ISDN dial backup, dialer watch, & routing protocols

[johndennison]

Hello.

I was using EIGRP and dialer watch for ISDN dial backup from a remote site to our main site. It worked fine, except that whenever I made any modifications to EIGRP (such as adding a new network or modifying the distribute-list) on the main router it broke all its adjacencies and caused the remote to dial up. I was told that OSPF was more stable so I set that up, and it seemed like it would solve the problem, except I can't get OSPF to communicate over the ISDN link. I egt messages in the remote saying "Apr 25 2005 13:59:35.996: OSPF: Rcv pkt from 172.16.23.1, BRI0/2/0, area 0.0.0.2 : src not on the same network".

I can see why this is a problem, but I can't figure out how to fix it. The PRI interface on the main router is configured with the IP address 172.16.23.1/24. When the ISDN connects it negotiates an address in the same network, however, it uses a host mask instead of the class C, so when it recieves the hello packet from the main router he discards it since the source isn't a part of the same network it was recieved on (due to the host mask). I've tried a bunch of stuff, but can't seem to get it to work. Here are pieces of the configs:

Main:

interface Serial1/0:23

description PRI for ISDN Dial Backup

bandwidth 56

ip address 172.16.23.1 255.255.255.0

ip access-group 110 in

encapsulation ppp

delay 3000

dialer idle-timeout 2147483

isdn switch-type primary-4ess

peer default ip address pool isdn-backup

priority-group 1

ppp authentication chap

ppp ipcp mask 255.255.255.0

router ospf 99

log-adjacency-changes

passive-interface FastEthernet2/0

network 172.16.23.0 0.0.0.31 area 2

network 172.16.24.0 0.0.0.255 area 2

network 172.16.250.0 0.0.0.127 area 0

Remote:

interface BRI0/2/0

description ISDN Dial Backup

bandwidth 56

ip address negotiated

ip access-group 111 in

ip nat outside

encapsulation ppp

delay 3000

dialer map ip 172.16.250.0 broadcast XXXXXXXXXXX

dialer watch-group 1

isdn switch-type basic-ni

isdn spid1 XXXXXXXXXXXXX

isdn spid2 XXXXXXXXXXXXX

no peer default ip address

ppp ipcp mask request

ppp ipcp address accept

router ospf 99

log-adjacency-changes

network 172.16.23.0 0.0.0.31 area 2

network 172.16.24.8 0.0.0.3 area 2

network 172.16.240.2 0.0.0.0 area 2

network 172.16.242.2 0.0.0.0 area 2

network 172.16.242.3 0.0.0.0 area 2

Any input would be greatly appreciated.

[Georg Pauwen]

Hello John,

configure ´no peer neighbor-route´ on the BRI/PRI interfaces on both sides. This will prevent the /32 host routes from being installed.

HTH,

GP

[johndennison]

Gp,

Thanks for the response. However, I'm getting the same results.

I think the problem is that the remote router is not getting or utilizing the negotiated netmask when his interface comes up.

[thisisshanky]

Have you cleared the routing table "clear ip route *" to see if that helps ?

[pkokhan]

The easiest solution is to assign a static IP/mask to the BRI form the 172.16.23.0/24.

Does you hub router will receive calls from just one remote office? If not I would recommend configuring dialer interfaces on the main router - one for each remote site.

[johndennison]

I did try using static addresses, and although it allowed OSPF to work I couldn't pass regular IP traffic for some reason. That's definitely an option if I could get that to work.

And, yes, my main router would be receiving calls from multiple remote sites. I'm not real clear on setting up dialer interfaces or how they could help me, though.