Subject: Route Distinguisher Id

From: "Rubens Gomes" <[email-masked]>
Date: Wed, 16 Oct 2002 19:39:10 +0000

My company (www.diveo.net.br) is getting ready to implement MPLS VPN in its 
IP backbone.  Right
now,  we are in the process of establishing conventions and strategies to 
name and identify things like
RDs, vrfNames, and such in the VPN VRFs.

A question has been raised regarding the strategy to be used for the RDs.  
Should the RD be unique
per VPN?  That is, within the same VPN, use the same RD in the different 
VRFs?  Or should we use a
distinct RDs for each VRF in the network?  From the perspective of network 
management it appears
to make sense to  use the same RD in a VPN because that would facilitate the 
correlation of VPNs
with RDs.  However, someone else here raised the possiblity  of NOT having 
unique routes when the
same RD is used, and is aiming at unique RDs in the network.  Here is 
basically what this person has
raised:

aim: make routes unique, distinguish between VRF on same PE
set: on the VRF and attached to all routes when redistributed into MP-BGP
rule 1: no 2 VRFs on the same PE may have the same RD
rule 2: the combination of <RD>:<ipv4 address> (=VPNV4-address) needs to be
unique in the provider network as BGP (MP-BGP) only forwards the best route 
(otherwise load-balance
won’t happen on redundant links)

The bottonline: Should RDs be unique or not?

Rubens S. Gomes
http://www.rubens-gomes.com

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From: Robert Raszuk <[email-masked]>
Date: Wed, 16 Oct 2002 22:08:42 +0200

> The bottonline: Should RDs be unique or not?

My recommendation would be to make them unique. If you want to discuss
pros & cons of both approaches fell free to send me mail offline as some
of them are simply vendor specific :).

Rgs,
R.

> Rubens Gomes wrote:

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From: Yakov Rekhter <[email-masked]>
Date: Wed, 16 Oct 2002 16:45:12 -0700

Rubens,

> The bottonline: Should RDs be unique or not?

If you use a distinct RD for each VRF, then it is possible to
autoconfigure such RDs (thus avoiding efforts in managing
allocation/assignment and configuration of RDs). Also, if you use
a distinct RD for each VRF, then it enables pretty straightforward
support for load sharing among multiple links of a multihomed site
(where the site is multihomed to different PEs).

Yakov.