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New Member

Frame-relay cloud redundancy

I have built a switched frame-relay network consisting of Cisco 2600/3600 routers. I would like to add redundancy to the frame-relay cloud (the NNI interfaces). E.g. ISDN back-up between two frame-relay switch routers. Is this possible? How would one provide for redundancy within the cloud without have to created alternative PVC’s.

New Member

Re: Frame-relay cloud redundancy

If you have a PVC from routerA to routerB, 2 common backup links are ISDN, or dial-up if not much traffic needs to go over it.

In order to do this, on your FR primary interface you would do the following (this is assuming certain cards you have)

(config-if)#backup interface bri0/0

(config-if)#backup delay 6 10

with the 6 being the amount of seconds after the primary link goes down before the backup would be brought up. The 10 being the amount of seconds the primary link would have to be up before the backup would go back down. Be careful that you don't set these too low. You don't want glitches (hiccups) in your connection to activate that ISDN line every few minutes.

As far as the ISDN interface goes, just configure it as if it was a real link. The backup interface command automatically puts the ISDN link in Standby mode.

Or you can just use a simple floating route. But glitches can bring it up and down constantly costing you lots of money. Of course there are some pretty cool things you can do with this like take one ISDN link and use each B channel as a separate backup link for 2 different FR links saving you some money.

I hope that gets you started.

New Member

Re: Frame-relay cloud redundancy

Thanks for the input, but it does not work. The frame relay switch is on layer 2 thus no ip routing is possible. Any other ideas would be appreciated. Thanks for the input so far.