The MPLS WG Archive

[Juerg.Fankhauser@swisscom.com]

Hi Sailendra,

I think that's because an advertized route can be associated with any number
and combination of RTs (depending on your VPN routing scheme), while it
carries exactly one RD as part of the address.

That means: Even if it would be possible in theory to resolve the routing
with RT alone, thanks to the RD it can be handled by regular (multiprotocol)
BGP processes and tables.

btw - P routers are not even BGP speakers in MPLS/VPN.

Regards,
-----------------------------
Juerg FANKHAUSER
swisscom AG, Bern
juerg.fankhauser@swisscom.com
-----------------------------



-----Original Message-----
From: sailendra mahanty [mailto:sailendram@future.futsoft.com]
Sent: Donnerstag, 21. Juni 2001 07:01
To: mpls@UU.NET
Subject: Use of RD in BGP/MPLS VPN


Hi All,

draft-rosen-rfc2547bis-03.txt clearly distinguish between RD and RT. The aim
of the RD is to resolve the ambiguity of IP4 address for IP address
overlapping situation.

IMHO when there is a BGP session between two PEs, the route advertise
information in UPDATE msg is not used by other BGP speaker ( P routers
specifically ).
If i am missing something in saying this please let me know.

If i am right in saying the last statemnet, the address overlapping can be
resolved at the peer PE by using RT.

Putting the question in other way, what way the RD value associated with a
route is used in the remote PE ?

Can anybody please help me to get clear picture of RD.

Regards,
-sailendra