From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Mon Jan 12 2004 - 15:29:20 GMT-3
At 12:30 PM -0500 1/12/04, Jonathan Hays wrote:
>you wrote:
>
>>I keep reading and hearing that you shouldn't inject LSA
>>type-5 into your
>>OSPF domain if you don't need to. Why not?
>
>= = =
>
>A lot depends on your topology, the size of your OSPF domain, the number
>of exits to the Internet, and so on.
>
>For example, suppose you had a small company network of less than 100
>routers and a single egress point to the Internet. There would be no
>point in injecting external LSAs into OSPF and filling up routing tables
>with unnecessary routes. A single default route pointing to the ASBR
>would suffice.
>
>The answer is, it depends.
>
Very, very true. If you have multiple exits, you will get more
optimal routing, at the cost of more overhead (especially if there is
flapping). How important is best-exit routing versus stability,
especially when you aren't going to be able to affect the return path
and may get asymmetrical routing? THAT depends.
At some point, it becomes less of a good idea to inject lots of
internals into any IGP, and a better one to implement reasonably
pervasive BGP and use the IGP to find quick alternate paths to BGP
speakers.
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