Subject: LDP/RSVP

From: "HANSEN CHAN" <[email-masked]>
Date: Sat, 15 Jul 2000 07:51:40 -0400

Hi folks,

I heard that there're some live MPLS network deploying LDP at the edge
and RSVP at the core. Do it mean that a LSP is established edge to edge,
part of it is done by LDP and part of it is done by RSVP? Or it is 3
separate LSPs established separately and somehow was spliced together
(like having 3 separate MPLS domains in the same physical network own by
one network operator)?

What might be the advantage of doing that? Appreciate any insight.

Cheers,
Hansen

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From: Robert Raszuk <[email-masked]>
Date: Sat, 15 Jul 2000 23:46:24 -0700

Hansen,

Your question is not very clear as you are not indicating what MPLS
application(s) are being used in those "live MPLS networks" you are referring
to. 

One of the possible architecture which may use LDP/RSVP in the way you have
described could be mpls-vpns with TE tunnels starting/ending either from/on PE
or P routers. In that scenario you would still be running LDP in your entire
domain. In addition to LDP to benefit from all TE capabilities you can use RSVP
to establish tunnels and by running a directed LDP session via those tunnels be
able to transport your VPN packets via those tunnels.

Second possibility could be establishment of 3 separate TE LSPs and "gluing"
them together with LDP by using label stacking capabilities of MPLS. That trick
could be used for example to build TE tunnel across multiple IGP areas/levels.

R.

> HANSEN CHAN wrote:

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From: "HANSEN CHAN" <[email-masked]>
Date: Sun, 16 Jul 2000 08:06:16 -0400

Robert,

To my understanding, the application is TE, not IP VPN.

Cheers,
Hansen