The MPLS WG Archive

["Manohar Ellanti" <ellanti@home.com>]

I think one commercial MPLS stack vendor has support for one side of LSP setup using LDP(CR) and the other using RSVP. I am not sure
about the extent of support. For instance Explicit and crankback semantics and how they can be translated between the two sides.

However I can imagine, instead of horizontal participation of the two signaling protocols, a vertical participation where a tunnel
might be setup using RSVP-TE and inside the tunnel number of LSPs to be setup using CR-LDP for instance.

Again probably it is best avoided using multiple signaling protocols over a single provider network. 2547 does mention use of LDP to
setup PE-PE tunnles. I remember a discussion on removing explicit reference to one particular signaling protocol from 2547. If 2547
does require LDP then probably the underlying physical connectivity between PE routers can be setup using RSVP-TE and VPNs
provisioned or PE-PE (per VPN specific) inner LSPs setup using LDP. Some one can  comment whether this makes sense.


-Manohar



----- Original Message -----
From: "David Charlap" <david.charlap@marconi.com>
To: <mpls@UU.NET>
Sent: Monday, February 19, 2001 9:31 AM
Subject: Re: CR-LDP and RSVP implementation


> djiang1@lucent.com wrote:
> >
> > I have a question regarding CR-LDP and RSVP implementation.
> >
> > I guess it is possible that both CR-LDP and RSVP implementations will
> > be supported on one LSR.
>
> Definitely possible.  And quite probable in the future.
>
> > However, is there any chance that both the implementations will be
> > called for one LSP setup?  Say, at the incoming interface, CR-LDP will
> > take the PATH message and pass it to some other MPLS processes.  At
> > the out going interface, RSVP will get some message from other MPLS
> > processes and does something in the middle and sends out another PATH
> > message to its neighbor node.
>
> I don't think so.
>
> The only way I can picture such a setup would require a transit router's
> ability to terminate one LSP, then initiate setup of another, and
> connect them internally.  Theoretically possible, but difficult to
> automate and of questionable utility.
>
> I think you may find MPLS networks where RSVP-TE, LDP and CR-LDP are all
> used for LSP setup at once.  And this may well result in multiple
> redundant LSPs between edge nodes.  But each individual LSP will almost
> certainly be set up through exactly one protocol.
>
> -- David
>