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ISDN and HSRP

I have two routers with HSRP.

Can I configure a backup ISDN if the two links are down?

Thank you

3 REPLIES
Bronze

Re: ISDN and HSRP

You can establish the primary HSRP interface using the standby priority command and configure the ISDN to be brought up if the secondary interface goes down which will achieve the closest to what you want, however, if the secondary interface fails, it would not be possible to prevent the ISDN from being activated even though the primary interface is still active.

Re: ISDN and HSRP

Re: ISDN and HSRP

Pretty easy really. Place the ISDN on the 'Primary' router (HSRP Active). If you use HSRP and track the Serial interfaces so you can fail initially from the Primary router to the secondary and then also track the Serial interface on the secondary router so that if it goes down it will fail back to the Primary router. Add some floating static routes to use the ISDN

Primary router HSRP priority of 100, tracking serial-X and decrement by 10.

Secondary router HSRP priority of 95, tracking serial-X and decrement by 10.

This way it will fail from Primary to Secondary if the Primary Serial-X goes down, then back to Primary if the Secondaries Serial-X goes down. Make sure standby preempt is enabled.

Andy

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