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Configuring Redundant Frame-Relay PVC



We have 3 rotuers, there are frame-relay services between Router1 & Rotuer2 and Router1 & Router3.

PVC between Router1 and Router2 is production link and up all the time.

PVC between Router1 and Router3 is redundant or shadow PVC which automatically becomes active if link between Router1 and Router2 is down.

As I have never configured redundant PVC so can someone please let me know how to configure it do I have to use same IP address is Router3 as in Router2. If someone knows about any document please let me know.



4 Replies 4


Is router 2 and router 3 at the same physical site? In other words you have site A where router 1 resides. Then there is site B where router 2 & 3 resides.

Sounds like you need HSRP between router 2 & 3 for the local IP gateway. Then I would use eigrp or ospf to manage the redundant PVC's between routers/sites.

Both the routers are in different physical location. currently we are using static routers in these routers for this link.What I want is if we the link between router1 and rotuer2 is down or we lose router2 than PVC in router3 to become active. And I want to know how do I have to configure the serial interface in router3.

Why not run eigrp or ospf and just cost the PVC's?

How is the interface on router 1 configured, are you using subinterfaces.

You will have to configure your router 3 interface with a separate IP than that of router 2.

The usuall method would be to configure router 1 with 2 subinterfaces, i.e one per PVC assuming that you have a single physical link with two PVC's configured. This will provide two seperate IP links from router 1, each of which will have its own IP subnet ( I usually use private addressing for each link with a 30 bit subnet mask to maximise the address useage (i.e and for one link and and for the other)

You can then either stick with your static routes and supply a higher metric for the backup link (i.e. a floating static route), or you can use EIGRP or OSPF to provide your routing.

If you are dealing with a very few number of routes, it is probably simpler to stick with the staic routes

Have a look on TAC for sample configs, there is also a usefull PDF called "Intial configurations for OSPF over Frame-Relay".

Hope this helps

Steve Kerr

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