Subject: RE: Route Distinguisher Id

From: "Shiv Agarwal" <[email-masked]>
Date: Wed, 16 Oct 2002 17:00:12 -0700

Rubens,

Can you ensure that the address space of VRFs participating in a VPN does not overlap?
If yes, then all VRFs in a VPN can be assigned the same RD. Also your point of correlating RDs with VPNs may not hold good for VRFs participating in multiple VPNs. Try to correlate VPNs using both RD and RTs.

Shiv.

-----Original Message-----
From: Rubens Gomes [mailto:[email-masked]]
Sent: Wednesday, October 16, 2002 12:39 PM
To: [email-masked]
Subject: Route Distinguisher Id

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: "Joe Lin" <[email-masked]>
Date: Wed, 16 Oct 2002 18:42:01 -0700

In the operational sense:

If you have unique RDs per VRF, it makes troubleshooting a lot easier
because you can make correlations easier.

But unique RDs will suck up more memory on the PE, at least that’s what
I gathered on cisco's website.

I don’t have that particular URL anymore. but do a search on cisco's
site and you should find it

-joe

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]] On Behalf Of Shiv Agarwal
Sent: Wednesday, October 16, 2002 5:00 PM
To: Rubens Gomes; [email-masked]
Subject: RE: Route Distinguisher Id

Rubens,

Can you ensure that the address space of VRFs participating in a VPN
does not overlap?
If yes, then all VRFs in a VPN can be assigned the same RD. Also your
point of correlating RDs with VPNs may not hold good for VRFs
participating in multiple VPNs. Try to correlate VPNs using both RD and
RTs.

Shiv.

-----Original Message-----
From: Rubens Gomes [mailto:[email-masked]]
Sent: Wednesday, October 16, 2002 12:39 PM
To: [email-masked]
Subject: Route Distinguisher Id

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)

Rubens S. Gomes

---

From: Yakov Rekhter <[email-masked]>
Date: Thu, 17 Oct 2002 05:45:30 -0700

Joe,

> But unique RDs will suck up more memory on the PE, at least that's what

While this may be correct for a particular vendor, do *not* assume that
it is correct for other vendors.

Yakov.

> I don't have that particular URL anymore. but do a search on cisco's

---

From: "Joe Lin" <[email-masked]>
Date: Thu, 17 Oct 2002 09:34:45 -0700

I apologize for my implication in my email..

I meant on cisco's website, they say it sucks up more memory on PE in
their implementation.

Other vendors does not claim this is an issue

-----Original Message-----
From: Yakov Rekhter [mailto:[email-masked]] 
Sent: Thursday, October 17, 2002 5:46 AM
To: Joe Lin
Cc: 'Shiv Agarwal'; 'Rubens Gomes'; [email-masked]
Subject: Re: Route Distinguisher Id

Joe,

Yakov.

---

From: Ajay Simha <[email-masked]>
Date: Thu, 17 Oct 2002 13:25:48 -0400

> Other vendors does not claim this is an issue

If I'm not mistaken, Cisco's docs recommend not using unique RD per site(of the same VPN). 
Unique RD per VRF is still recommended and fine.

-ajay