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Cisco frame relay network Disaster recov

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by lmyoungmcp

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I am trying to put together a disaster recovery plan for a frame relay network using mostly Cisco 1600 routers. The problem is that we currently have 11 sites going to a data center for normal operations; I am talking to our network provider on a backup plan to re-point the routers at the branch locations to the backup site. They asked me if our routers had the ability to re-point the DLCIs on the branch routers to the backup DLCI if the main site goes down. Being a Microsoft guy I have no cluehow to check that and the Cisco docs are cryptic. I found were it mentioned dial backup and that is sort of what I am looking for but not exactly.

8 replies

by celarix, inc.

Depending of the routing protocol you are using it can be accomplished a variety of ways.

In this scenario I would probably use static routes unless you are anticipating explosive growth.

With static routes then you can add a second route for each site that points to your backup location if the primary data center link fails or timesout.

If your routers have at least IOS 11.3 then you can assign multiple DLCI's to the sub-interfaces and assign priority to the DLCI that points to your primary data site.

If you have multiple routers at each remote site then you can use HSRP to assign a virtual Default Gateway to your clients that points to the 2 or more actual ip addresses of the routers.

Let me know if you need more information.

by wcraigmiles

Cisco dial on demand will let you connect to the other route when the other fails. I don't have the documentation in front of me, and I'm not sure the the 1600 has the full feature set for that, but we have that running on several routers but they have multiple frame interfaces. The other solution is to have another router in another location take over as the failed router. You really aren;t supposed to run two devices with the same IP but if you are really into Cisco IOS and willing to do some custom programming you can make it work.

There was an article in one of the trades talking about a firm in New York that did something similiar. I do belive that their routers were a bit more high end.

by kevin anderson

This won't be the answer you're after, but you could try it.

Set up a Linux box with 3 NICs. One for your internal network, one for your primary network, and one for your backup connection.

Configure your primary site as a default route.

Write a script to ping your primary site. If the ping fails, delete the default route, and add a default route pointing to your secondary site.

The script should only be 3 or 4 lines long (at most).

This makes the Cisco's redundant.

However you do it, make sure the DNS server you use is reachable after the primary link is down. That's a common thing to forget.

Kev.

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