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Community Member

ISDN bridge group

Hi there,

I got a remote site with two Cisco 2503, as 2503-1 and 2503-2. Both of the 2503 ethernet are connected as same subnet. There is a WAN link connecting between 2503-1 and HQ with OSPF. A bridge is currently between remote site ethernet segment, WAN link and HQ ethernet segment. Now for resilience purpose, BRI port of 2503-2 will be configured. Bridged traffic is needed to pass through the ISDN line. May I ask that how can the ISDN line be automatically shut down after the primary WAN link recover? For your information, the IOS version for the 2503 is igs-d-l.111-2 and with only 4MB RAM and 8MB flash.

thanks a lot


VIP Purple

Re: ISDN bridge group


I am not sure if I fully understand your setup, but I would say if you make the BRI interface a member of the bridge group and configure the primary interface with the ´backup interface bri0´ command the redundancy should work.


Georg Pauwen

Community Member

Re: ISDN bridge group

another option with the OSPF is to have only certain ip traffic be significant to the dialer for the isdn link and then have a floating ip route. When the main link resumes then the preferred ip route would return to the permanent link. Since only certain ip traffic was interesting to the dialer and it started to go the path of the permanent link, then the isdn would hang up and your bridged traffic would go the path of the permanent link as well.

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