Subject: RE: MPLS LSPs and ATM PVCs

From: Dmitry Ryumkin <[email-masked]>
Date: Mon, 26 Feb 2001 09:12:18 -0500

Paul,

Generalized MPLS defines procedures for bi-directional LSP setup.

Regards,
Dmitry Ryumkin

 -----Original Message-----
From: 	[email-masked] [mailto:[email-masked]] 
Sent:	Monday, February 26, 2001 8:52 AM
To:	Paul Moore
Cc:	[email-masked]
Subject:	Re: MPLS LSPs and ATM PVCs

HI Paul,

I believe RSVP is never intended to set up two LSPs using one single
operation.  We will have to use two RSVP signalling operations to set up
the two LSPs, one for each direction, even if the PVC may be used
bidirectionally.

Regards,
Jane D. Jiang

Paul Moore <[email-masked]>@UU.NET on 02/26/2001 08:11:29 AM

Sent by:  [email-masked]

To:   [email-masked]
cc:
Subject:  MPLS LSPs and ATM PVCs

Hello,

I have a question about MPLS and ATM. ATM point-to-point PVCs can be
either uni-directional or bi-directional. MPLS LSPs are only
uni-directional. Is there any work being done concerning bi-directional
LSPs, for example, to allow two LSPs to be established by a single RSVP
signalling operation?

I've just joined the list, so apologies if this has already been
discussed.

Thanks,
Paul

--
Paul Moore
Alcatel Bell
+32 3 450 3536
[email-masked]

---

From: Paul Moore <[email-masked]>
Date: Mon, 26 Feb 2001 17:54:35 +0100

Dmitri,

Where is that stated? I've checked in the MPLS Architecture documents,
searching with the "bidirectional" and "bi-directional" keywords, and I
haven't been able to find it mentioned.

On the other hand, the two applicability documents for CR-LDP and RSVP-TE both
state that bi-directional LSP set up is not yet supported:

Applicability Statement for CR-LDP (13805 bytes):
    "CR-LDP specification only supports unidirectional LSP setup.
Bi-directional LSP setup is FFS."

Applicability Statement for Extensions to RSVP for LSP-Tunnels (16573 bytes):
    "The RSVP-TE specification supports only unidirectional LSP- tunnels.
Bidirectional LSP-tunnels are not supported."

Many thanks,
Paul

PS Thanks Jane for the response.

--
Paul Moore, ext 53536
03/450.3536

---

From: Patrick McGleenon <[email-masked]>
Date: Mon, 26 Feb 2001 18:12:36 +0100

Hi Paul,

It's true that traditional MPLS supports only unidirectional LSPs; it's also
true that if you look in the IETF draft "Generalized MPLS - Signalling Functional
Description" (draft-ietf-mpls-generalized-signaling-01.txt) in Section 4 you will
find a discussion of bidirectional LSPs in the context of Generalized MPLS.

Regards

Patrick

---

From: Eric Gray <[email-masked]>
Date: Mon, 26 Feb 2001 12:28:48 -0500

Paul,

    Any references to bi-directional LSP establishment that
might have appeared in the architecture or applicability in
in the MPLS working group would have been either an
exceptionally insightful forward references, or wrong.  :-)

    Dmitry refers to relatively new work.

--
Eric Gray