From: Tom Rogers (cccie71@yahoo.com)
Date: Sun Jul 11 2004 - 15:55:18 GMT-3
Bob,
What you said is correct. What I am saying if their re equal routes for the same destination and default route selection is not changed and all the parmeters re equal, then only the oldest route will be installed or from the lowest router-id.
So in this scenario, I dont know exactly the details......
Sub-AS 65267 - Sub-as 65038 - Sub-as65145
Router 65038 if learning same route from both the neighboring AS's and everything is equal as to what Koen is saying, then that route will be installed and showing the best path from the lowest neighbor router-id.
But only 1 route is installed by default.
Tom
Tom
Bob Sinclair <bsin@cox.net> wrote:
Tom,
AFAIK, it is true of all flavors of BGP that only the best path, the one
used locally, is eligible to be advertised. This includes EBGP, IBGP and
Confederation BGP. This is basic out of RFC 1771. If anyone can document
otherwise, please send it my way.
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net
----- Original Message -----
From: "Tom Rogers"
To: "Koen Peetermans" ;
Sent: Sunday, July 11, 2004 11:42 AM
Subject: Re: BGP confederation prefix behaviour = IBGP ?
> I dont know the whole scenario here.... but if everything's equal under
bgp route selection criteria, then on 65038 as router will select the oldest
route as the best route and then then from the lowest router-id (change the
router-id for if u want to a route preferred and reboot)
>
> Koen Peetermans wrote:Hi,
>
> I was wondering about BGP confederation functionality which I experienced
on
> an IEWB lab (#8) :
>
> Is it true that Confederation peers in different Sub-as'es only will
forward
> the best prefix to eachother (like IBGP) ?
>
> For example :
>
> AS54 AS54
> | |
> EBGP EBGP
> | |
> CONF AS100 CONF AS100
> Sub-AS 65267 - Sub-as 65038 - Sub-as65145
>
> Sub-as 65038 will get the same BGP prefixes from both
> 65267 & 65145, but with different next-hops to AS54.
>
> However, it will select only the best path for a prefix and only send that
> further to the next sub-as ? Is this correct behaviour ?
> I check Internet Routing Architectures and Routing TCP/IP VOL II but
didn't
> find something describing this (maybe didn't look good enough).
>
> Thanks and kind regards,
>
> Koen.
>
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