From: Adhy (no email)
Date: Wed Feb 06 2008 - 01:56:08 EST
Hi list,
Is it possible to prove that if we have 3 RRs with each has different
cluster ID and each pointing to each other may create loop ? What I've
been doing is to simulate (not simulate by doing it on simulator, but
by drawing it on visio) BGP update mesg if the update comes from eBGP
then it propagates throughout the network.
Please refer this simplified topology below.
+--------+ +-------+
| | | |
| RR1 | --------- | RR2 |
| | client | |
+-------+ +--------+
\ /
client \ ASX / client
\ /
+-------+
| |
| RR3 |
| |
+-------+
Note :
1. RR1 is RR on the cluster ID 1
2. RR2 is RR on the cluster ID 2
3. RR3 is RR on the cluster ID 3
4. each RR is pointing to each other as a RR client (not iBGP peer)
5. on each cluster there are more than one RR client
From what I understand, this kind of topology is _not_ recommended (I
refer to http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/icsbgp4.htm#wp7158).
But I really need to prove it(to show it to my client). I've checked
the specs (rfc4456) and try to follow the route reflection behavior
based on the specs. It leaves me with more headache. So please bear
with me with another questions as follow :
1. If the update is propagated from RR1 to RR2 then RR3, will the
ORIGINATOR_ID on the update mesg still RR1 ?
2. and will the CLUSTER_LIST being used ? the cisco specs only said
that the CLUSTER_LIST being used if the update mesg is reflected from
clients to non clients. how about from clients to other client (which
this client also a RR for another cluster) ?
I've assumed that both ORIGINATOR_ID and CLUSTER_LIST is always used
when route is being reflected and come to conclusion that the loops
will not occur. Is it correct ?
Any comments will be appreciated. thanks.
regards,
-- -adhy
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