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New Member

OSPF enviroment with Backup on ISDN BRI

I have a network with 20 OSPF routers connected with Serial lines.

Now I must configure ISDN Backup lines and I need to use OSPF on all ISDN backup lines !!!

While soluction I can use ????

I have read that snapshot routing is supported by RIP, IGRP but NO OSPF.

Thank's and ..ciao

Cisco Employee

Re: OSPF enviroment with Backup on ISDN BRI

You can use many different ways to do that. One of the most usable way is to configure the dialer watch. With dialer watch, the router monitors the existence of a specified route over the primary interface (serial interface in your case)and if that route is not present, it initates dialing of the backup link which is isdn.

Pl. visit following url for sample config and explanation


you can visit following url to decide which backup scheme is the best suited for your network.

New Member

Re: OSPF enviroment with Backup on ISDN BRI

OK !!

Thank' s

I have 5 Routers 2500 with IOS 11.0, 11.1

Can I have problem with Dialer Watch ????


Re: OSPF enviroment with Backup on ISDN BRI

Yes, you will have problems with dialer watch. Dialer watch was not introduced until IOS 12.0 and Cisco recommends using at least IOS 12.1(7) because of bugs in early releases of dialer watch. FWIW I have been getting equivalent results for years using dial on demand routing and appropriately configured floating static routes. See the white paper on my web site on "BGP Driven DDR" for how to get dialer on demand to dial even if you can't guarantee the presence of "interesting traffic." More details are in chapter five of my book.

Good luck and have fun!

Vincent C Jones

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