Re: Best Practice: 2routers, 2isp, 1AS

[Brian Feeny <bfeeny () mac com>]

There are alot more questions that need to be asked.  Like how much address space do you have to announce? What routes 
are you getting from each ISP?

Assuming you are an end user, and knowing the very limited information I know at this point, I would make sure that 
these two routers LAN interfaces are in some sort of transit vlan/subnet with my downstream router, which would also be 
participating in iBGP.  Alternately you could have that router do VRRP/HSRP with your two border routers, but I prefer 
iBGP.

I would then setup both routers using OER (Optimized Edge Routing, i think now known as Performance Based Routing), to 
handle outbound.  You could just announce your /24 out each provider (assuming that's what you had) to handle inbound, 
or if you have larger than that you could announce the aggregate out both and more specifics out each to do some type 
of balancing.

Its hard to say there is a best practice here, as there are so many scenarios.  I will say that I like OeR/PfR for edge 
customers who are dual homed.  BGP is very arbitrary, and its nice to have some real metrics that mean something to 
play with :)

Brian


On Apr 7, 2010, at 1:14 AM, Beavis wrote:

> Greetings!
>
>   Want to ask out anybody on the list about a "best practice" of the
> setup below:
>
> - 2 ISP's (A & B)
> - 2 Routers (A & B)
>
> I want Router-A for ISP-A, Router-B for ISP-B and have Router-A &
> Router-B talk and be able to pass routes on each side in an event of a
> physical failure on one of the Routers.
>
> I was planning at first to setup a multi-home BGP, but I want to have
> physical redundancy as well.
>
> ASCII-diag
>
> =--[RouterA]--isp1(bgp)
> L    |
> A   iBGP
> N    |
> =--[RouterB]--isp2(bgp)
>
> Any recommendation would awesomely appreciated.
>
> -B
>
>
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