Subject: draft-ietf-mpls-rsvp-lsp-tunnel-08.txt

From: Anouk Rocher <[email-masked]>
Date: Thu, 12 Jul 2001 12:23:10 -0400

This didn't seem to get posted even though I mailed
it several hours ago. So here it is again - Can one
of the draft authors comment.

Further can such a clarification be added to the 
draft for reference.

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Hi,

Running through many MPLS RFCs/drafts and trying to co-relate them
with the base RSVP spec in RFC 2205 (and 2210), I can 't seem to find
a clear statement anywhere on how RSVP objects are used for the
purposes of MPLS based Traffic Engineering.

Is it the case that the ingress node trying to set-up an LSP
encodes the bandwidth it needs for that LSP, INTSERV style by
filling out the Sender Tspec? Are all the fields
"Token Bucket Rate", "Token Bucket Size", "Peak Data Rate",
"Minimum Policed Unit" and "Maximum Packet Size" needed? Or is it
safe to just specify the bandwith needed as "Peak Data Rate".

Are any of the other objects like ADSPEC and RSPEC needed for
Traffic engineering (beyond basic conformance needs for RSVP to
function properly)?

Can one of the authors of draft-ietf-mpls-rsvp-lsp-tunnel
(Vijay, Lou, ??) clarify this?

Many thanks.
Anouk

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From: David Charlap <[email-masked]>
Date: Thu, 12 Jul 2001 12:45:01 -0400

> safe to just specify the bandwith needed as "Peak Data Rate".

The resources reserved are in the FLOWSPEC sent from the egress router
to the ingress router.  This FLOWSPEC may be one of three kinds of
intserv classes: Null (meaning best-effort), Controlled-Load, or
Guaranteed Service.

The TSPEC in the Path message is used by the ingress router to inform
the egress router of what it wants to reserve.  Under most MPLS
implementations, the egress router will try to reserve this amount,
although it is possible for policy decisions to choose a lower amount.

The ADSPEC in the Path message, if used, serves two purposes.  It
gathers information about the network along the path so that the egress
router will have an idea of what resources are available, and it may be
used to request a particular kind of intserv class for the FLOWSPEC.

This is all straight RSVP and has nothing to do with traffic
engineering.

Traffic engineering is made possible via the new objects introduced in
RSVP-TE.  Specifically, SESSION_ATTRIBUTES and EXPLICIT_ROUTE.

-- David