Subject: [Diffserv] RSVP/diffserve and PHB/PDB info for ingress nodes

From: Dave Hotlosz <[email-masked]>
Date: Thu, 21 Sep 2000 08:55:48 -0700

Hi,
I have a question I haven't seen addressed yet, again if I missed it a
pointer
is great.

First I've seen some comments about ensuring proper capacity of the
DS domain to service
all the traffic that ISP can send under the SLA agreements. I've noticed
that some venders
are using RSVP to allocate resources for diffserve traffic. Is this
something that most if not
all will be doing in order to ensure proper bandwidth for diffserve
traffic? Or is it that the
SLA and policys in place will require ingress nodes to limit traffic
into the DS domain and
the number of ingress nodes into a particular domain are limited in
order to service all ingress
nodes up to the SLA requirements? I haven't seen this specified anywhere
and it seems like
a missing piece to me.

The other part I'm concered with is the fact that DS domains can have
differing actions on a
DSCP and I don't see anyway of finding out what those actions are from
the DS domain.
Will a ingress node only enter one DS domain or can it enter more than
one DS domain.
Should the ingress node be able to query a DS doamin for PDB/PHB and
adjust it's DSCP
to match the domain? If it is using a MF classifier does it use RSVP to
ensure the DS domain
treats the packet at the right classification and service level?

In RSVP you can make sure the network will reserve bandwidth for your
traffic and you get
confirmation about the network connection and how it will handle it. I'd
like to see a similar
mechanism for diffserve where you can query a DS domain and find out
PDB/PHB for a domain
as well as a way to register priority for values in the fields that a DS
domain uses in addition
to the DSCP in a domain that does MF classification.

I think the ingress node and the DS doamin should have a defined
interface for getting and setting
this information.

Also if it will be common to be using RSVP and diffserve together in a
DS domain that their
use together should be defined. This will help resolve the questions
about allocation and use
of DS domain resources when traffic in a node or to a egress exceeds
configured capacity.

Thanks,
    Dave

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---

From: Brian E Carpenter <[email-masked]>
Date: Mon, 25 Sep 2000 15:39:59 -0500

> nodes up to the SLA requirements? I haven't seen this specified anywhere

Yes, it's required that DS domains police incoming traffic, which is why
the traffic conditioning described in the router model includes
policing actions. The diffserv configuration at ingress routers has to
include the necessary policing parameters. These will be derived from
COPS, SNMP or any other method of router configuration. And they will
be needed regardless of whether RSVP/diffserv integration is in use - that
simply adds a dialogue between the end system and the ingress router.

> treats the packet at the right classification and service level?

If two domains touch but have incompatible SLAs (i.e. they treat the
same DSCP differently) there will be traffic conditioning at the boundary.
This is assumed to be statically configured, not discovered dynamically.

> mechanism for diffserve where you can query a DS domain and find out

That's exactly what diffserv doesn't do. Diffserv service classes
are agreed and configured in advance, not discovered or created
dynamically.

> to the DSCP in a domain that does MF classification.

Can't parse. 

> interface for getting and setting

We explicitly chose not to define dynamic signalling for diffserv,
to avoid scaling problems.

> use together should be defined. 

See ISSLL.

> This will help resolve the questions
> about allocation and use

That's an operational matter of configuring x resources for IntServ and 100-x
for DiffServ. 

   Brian