Subject: BW reservation over Diffserv using RSVP

From: Shahram Davari <[email-masked]>
Date: Wed, 23 Feb 2000 14:45:28 -0800

Hi,

I know that the following draft by Yoram Bernet et-al: 

http://www.ietf.org/internet-drafts/draft-ietf-issll-diffserv-rsvp-03.txt

addresses the usage of RSVP for dynamic Admission Control in a Diffserv
cloud. Has anybody extended this operation for actually reserving BW over a
Diffserv cloud. By reserving BW I mean adjusting/tuning the pre-configured
(provisioned) BW in the RSVP path for each Diffserv Class?

Thanks,
Shahram

---

From: Yoram Bernet <[email-masked]>
Date: Wed, 23 Feb 2000 22:12:58 -0800

See Fred Baker and co-authors draft on aggregate rsvp, in the same working
group. I think that it does what you mention.

Y

> -----Original Message-----
> From: Shahram Davari [mailto:[email-masked]]
> Sent: Wednesday, February 23, 2000 2:45 PM
> To: [email-masked]
> Subject: BW reservation over Diffserv using RSVP
> 
> 
> Hi,
> 

Thanks,
Shahram

---

From: Shahram Davari <[email-masked]>
Date: Thu, 24 Feb 2000 11:31:51 -0800

Hi Fred,

I am trying to understand the BW reservation in a Diffserv network using
RSVP. I have read your Aggregate RSVP draft and I have the following
questions:

1) Do you require a two level hierarchical scheduling in the interior nodes
(i.e., a level of scheduling before the class queues)? in other words do you
require per-class queuing only (the same as Diffserv) or per-RSVP-aggregate
queuing in addition to per-Class-queuing? in the former case all the
Aggregate-RSVP BW requests passing through the same ingress and egress
interfaces of a node (not necessarily following the same path), can be added
together and a single queue (depending on the DSCP) be used for all of them,
while in the latter case each RSVP-aggregate will reserve a separate BW and
the packets of that flow don't share the same queue (very much like Intserv
or ATM VC scheduling).

2) You mention that it is better to use different PHBs for the BW signaled
flows (using aggregate RSVP). Can we use the same PHB for both provisioned
and signaled traffic, but use the RSVP-aggregate signaling to fine tune the
provisioned BW assignments to Diffserv classes in interior nodes?

Thanks,
- Shahram

> From: Yoram Bernet [mailto:[email-masked]]
> Sent: Thursday, February 24, 2000 1:13 AM
> To: Shahram Davari; [email-masked]
> Subject: RE: BW reservation over Diffserv using RSVP
> 
>

---

From: Fred Baker <[email-masked]>
Date: Mon, 28 Feb 2000 12:37:02 -0800

At 11:31 AM 2/24/00 -0800, Shahram Davari wrote:
>(i.e., a level of scheduling before the class queues)? 

I don't require anything in particular in the queuing. The question is "can
we reserve bandwidth for a stream of traffic marked with a given code
point", and the answer is "yes".

That's not to say that fancy queuing might not be useful. But at most what
is required is that the queuing support the reservation by giving the
needed bandwidth to the class of traffic, and that it conform to the
controlled load specification.

>provisioned BW assignments to Diffserv classes in interior nodes?

I think you mixed some concepts there. To me, a DSCP is something one uses
to identify traffic, a PHB is a document that describes what you will do
with traffic that is so marked, and various other configurations are
required to implement the PHB. Can you use the same PHB for different
classes of traffic? Yes, absolutely. But you cannot mark them the same. If
they are different classes of traffic, to differentiate them, you need
differing DSCPs.

To accomplish literally what you said, I think you provision the network to
believe that there needs to be some amount of provisioned capacity between
given ingress and egress points, and you set up reservations for that
amount. Signalled traffic might increase those provisions. So you could
certainly write a policy that achieved that.