Subject: RE: [Diffserv] RSVP vs DiffServ

From: "Albert Manfredi" <[email-masked]>
Date: Thu, 18 Nov 1999 12:38:00 -0500

Yoram Bernet wrote:

> Albert Manfredi wrote:
> > My description would be that RSVP is thought by some
> not to "scale
> > well" in very large networks,
>
> RSVP is just a signaling protocol. It is traditionally
> associated with
> Intserv and with per-flow trafic handling mechanisms. The
> scalability
> concerns are really with the per-flow trafic handling
> mechansism more than
> with the signaling per-se.
>
>   and that therefore diffserv is being
> > developed to provide QoS within the network core. RSVP
> is instead
> > used at the edges,
>
> Let's look at this a little further. What do we mean when
> we say "RSVP is
> used at the edges". RSVP is an end-to-end signaling
> protocol, so - RSVP
> travels through every device on the end-to-end path
> through the network.

Yes, but it doesn't operate to provide QoS knobs within the diffserv
domain. As was proposed in one of the diffserv drafts at the recent
IETF meeting, it's possible to use RSVP as an admission control
protocol at the diffserv edge. Or other means could be used instead.

> The
> question is - who listens to RSVP? Typically, we would
> expect devices to
> listen to RSVP if they are serving as ingress points to
> valuable or
> congested regions of the network. An example is the
> ingress router to a
> diffserv network (at the edge). Another example might be
> a router serving a
> WAN connection. The fact that certain devices listen to
> RSVP does not
> necessarily mean that they apply per-flow traffic
> handling.

But, to summarize, a diffserv core router does not listen to RSVP.
Not unless we really change the diffserv charter.

> RSVP is used end-to-end.
> Aggregate traffic handling (a.k.a. diffserv)

AND per hop behaviors vs per microflow reservations (the latter
being the RSVP and ATM approach to guaranteeing QoS) are used within
the diffserv core.

Next thing you know, this discussion will be moved to
diffserv-interest.

Bert
[email-masked]

_______________________________________________
diffserv mailing list
[email-masked]
http://www.ietf.org/mailman/listinfo/diffserv
Archive: http://www-nrg.ee.lbl.gov/diff-serv-arch/