Subject: RE: MPLS Performance analysis.....

From: Larry Cox <[email-masked]>
Date: Wed, 07 Jun 2000 14:12:05 -0700

At 11:56 AM 6/7/00 -0700, Bora wrote:
>Yakov,
>
>It is a well known fact at this point we can make IP lookups as fast we can
>do MPLS lookups.
>
>So the lookup speed advantage of MPLS does not exist anymore which I believe
>was the point that was being raised.
>
>Bora (just catching up with my old mail)

(Initially I sent this off list but I think it may be applicable to a list
topic)

When one has 120K+ VoIP calls active on one OC192 fiber link and it becomes
necessary to move these calls enmass from route a to route b, moving a
labled path is much easier than handling all of the IP routing. It is
rather important to not have major underruns or overruns in the audio path
at the receiving end. Ideally, 200MSec or less to re-route all 120K+ voice
streams is prefered (30 MSec to avoid underruns).

Larry

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From: Curtis Villamizar <[email-masked]>
Date: Thu, 08 Jun 2000 10:27:01 -0400

> streams is prefered (30 MSec to avoid underruns).

Larry,

One might consider using CIDR addressing so that only a few prefixes
were rerouted.  I seriously doubt anyone would advertise 120K /32 IP
prefixes to handle 120K voice streams.  In this respect, MPLS can be
considered to be another form of route (or more correctly control
information) aggregation.

The major benefit of MPLS in your example would come from MPLS
local-protect.  Note that without local-protect, the one way delay
back to the ingress could exceed the 30msec.  Quite obviously, no IGP
would converge in that time so IP routing wouldn't respond in that
kind of time, but neither would MPLS reroute initiated at the ingress.

Curtis

---

From: Rajiv Papneja <[email-masked]>
Date: Thu, 8 Jun 2000 13:56:34 -0400 (EDT)

> streams is prefered (30 MSec to avoid underruns).

  Hi Larry,

  I would support your point here, but this could only be possible with
use of local repairs as it is the key to maintaining voice calls and other
high priority sevices.

  In MPLS, there are couple of techniques available with which this could
be achieved. This could be either splicing or Label stacking. In the
former technique an alternate LSP is pre-established from the point of
protection to the destination through a path bypassing the downstream
elements that are being protected. Once the failure is detected, the
Forwarding entry for the protested LSP is updated to use the label of the
bypass tunnel. The latter method of local repair uses the advantages of
label stacking.

 Further, this could make the repairs happen in the same time frame as the
SONET restoration.     

 There are some drafts available at the ietf site which refer to
these, like  draft-swallow-rsvp-bypass-label-00.txt.

 Take care

 Rajiv

********************************
Rajiv Papneja (GRA)
Advanced Internet Laboratory
George Mason University,
G10, Johnson Center,
Fairfax, VA 22030-4444
Tel: 703.993.4700
email: [email-masked]
********************************