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Migrating from NAT to Routing

Unanswered Question
May 26th, 2006
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I have a few routers (2621s and 1811's) connected to two different ISP's. Both ISP's give me ethernet interfaces to their service. One is a Fibre Optic Link and the other is several ASDL lines. On each of the routers I have configured NAT and static routes to get to the internet with supplied ranges from each ISP.

This works relatively well, however, since we support many clients via VPN connections from our network to theirs, NAT is becoming more of a pain than it's worth.

I do have 2 class C subnets at my disposal which we currently use in-house. We really don't 'need to use' NAT.

I have contacted each ISP and asked what routing protocols they support and both came back with BGP.

I have enough Cisco experience to know that I should take a course on BGP routing. That being said, I'd like to ask the experts here a few questions:

1) Will BGP be the best routing protocol for my type of network?

2) Will the current Cisco course offerings be useful to me?

3) Should I expect to be able to setup routing to both ISPs using my Fibre as primary and 1 or more of the DSL circuits as backup?

4) How well do Cisco IOS routers and Nortel Contivity Switches work together for routing purposes?


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gwhuang5398 Fri, 05/26/2006 - 10:58
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1) BGP is the best routing protocol between you and your ISP. That's the primary advantage of BGP - to set up routing policies.

2) Cisco course on BGP is a good one. You may have a lot experience already, but that course is pretty in depth and complete. Should be helpful.

3) You can use BGP to define primary and backup routes by using local preference and weight, as examples. There are other settings you can use in a BGP route selection process.

4) There are BGP parameters that are defined in standards so Cisco and Nortel can talk to each other for those settings. Cisco also has its own implementations, such as weight, that may not be implemented by Nortel and others. Recommend to verify with Nortel for specifics that you may have questions.

Hope this helps



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