From: Peter Grewal (peter@avient.ca)
Date: Tue Jun 03 2008 - 12:44:37 ART
I have done quite a bit of reading on this, and was looking for
clarification on something. I have an example whereby next-hop-self was used
within a peering relation between two AS that make up a BGP confederation.
Hence I was trying to understand why this would be used if routes are
propagated in an iBGP fashion.
Example AS25----[AS65400---AS65401]---AS255
If I put a next-hop-self on the peering between AS 65400 and AS65401 (both
part of confederation 200), why would I want to use this ? I would see the
only place to put the next-hop-self command would be on the true eBGP
connections for the purposes of establishing NLRI, if I don't have routes to
the peers IP. Which in this case should be to AS 25, and AS 255
respectively.
Thank you.
Peter.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Piyoush Sharma
Sent: June 3, 2008 11:30 AM
To: Peter Grewal
Cc: ccielab@groupstudy.com
Subject: Re: Question regarding Confederations and when to use next-hop-self
Hi Peter,
I'd advice you to read Internet Routing Architecture by Sam Halabi. I
believe it to be the BGP Bible. If you read it, you'll find it says where
next hop processing is concerned, bgp confederation (while peering between 2
private AS's) would follow the principle of iBGP and NOT modify the next hop
values. Its only modified in "true" eBGP peerings.
If any of the (BGP?)Gods here think I have mistaken the behaviour, please do
correct me and provide the right explanation :)
Piyoush
On Tue, Jun 3, 2008 at 8:06 AM, Peter Grewal <peter@avient.ca> wrote:
> Guys,
>
>
>
> Could someone please provide some clarification as to when to use
> next-hop-self between AS's within a BGP confederation. I understand that
> when you set up the confederation that the peering arrangement is eBGP
> based, but the actual route processing takes place as similar to iBGP. On
> that assumption, would I only place next-hop-self on routers that have
> peering relation with EBGP peers that are outside the confederation, if I
> require NLRI ?
>
>
>
> Thank you.
>
>
>
> Peter.
>
>
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