[Csci551-talk] Question regarding Route Reflectors

[John Heidemann]

On Wed, 10 Mar 2004 12:34:34 PST, suresh venkataramani wrote: 
>I think the IGP provides the routes by which one can reach any other router in
>the given AS. But you still need to propagate the routes learned via E-BGP to
>other interior routers. This is done via I-BGP where each router connects with
>evry other router( Full mesh ..can be multihop).The interior routers cannot
>propagate these routes learned over I-BGP hence the need for a full mesh. Also
>the next hop field does not change in these routes and it remains that of the
>gateway router.
>
>----- Original Message -----
>
>From: muralidharan murugan <murugan at usc.edu>
>
>Date: Wednesday, March 10, 2004 12:05 pm
>
>Subject: [Csci551-talk] Question regarding Route Reflectors
>
>> I think route reflectors are used to overcome the drawback of full-mesh
>> with I-
>> BGP. But since I-BGP is used for sending policy directives to routers with
>> in
>> an AS, why does it have to support route advertisements which should be
>> done
>> by the IGP that coexists?

Very good question.

Suresh's answer is correct.  The IGP may provide internal routes, but
I-BGP is used to propagate external routes, probably with policy
information.

   -John Heidemann