Subject: [NSIS] summary of thread on data and signalling path

From: David Partain <[email-masked]>
Date: Thu, 31 Jan 2002 15:06:25 +0100

Hi all,

Here I go again, trying to digest a Monster Thread...

The question posed is, "Do signalling and data need to follow the
same path in order to achieve what we're after with NSIS?"

Marcus started this thread by stating that he doesn't think this
should be a requirement.  I think we need to consider the
scenarios.

 - There are absolutely going to be cases where a centralized
   entity will take a decision about QoS requests.  In this
   case, there's no question there is no need to have data
   follow the signalling path.

 - There are absolutely going to be cases where there will _not_
   be a centralized entity managing resources and that the
   signalling will be used as a tool for resource management.
   For various reasons (such as efficient use of expensive
   bandwidth), one will want to have fine-grained, fast,
   and very dynamic control of the resources in the network.

 - There are going to be cases where there will be neither
   signalling nor a centralized entity (overprovisioning).
   In this case, the question posed just doesn't matter :-)

There are other possibilities as well.

Perhaps I'm being repetitive, but it's seems to me that the
important issue is that the domain answers the question,
"May I have what I want?"  Whether it bases the answer on a
centralized entity saying, "Sure, have a good time" or based
upon hop-by-hop verification of resource availability and then
allocation is not really important.  It's the combination of
domain answers which is important.

I think this follows very closely with what Ilya Freytsis wrote
on Tuesday:  "If you view the domain with a QoS technology
as a virtual router than NSIS signaling used between those
routers follows the same path as data. What happens within
the router is not a NSIS business."

As I see it, NSIS must accept all of these possibilities.
I also believe that we need to have standardized ways of
implementing both approaches, not just a domain-specific
free-for-all.    We need to define the interaction between
higher-level NSIS signalling that answers The Domain Question,
which I think will follow the same path as data, and the work
that's done within the domain to answer that question.

The NSIS protocol must be one of the options available for
managing QoS within a domain, but of course a different solution
can be chosen.  That solution may not require that user and
signalling data follow the same path.  However, if the NSIS
protocol is used within the domain, this may be required.

Cheers,

dlp

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---

From: Michael Thomas <[email-masked]>
Date: Thu, 31 Jan 2002 08:54:51 -0800 (PST)

>    follow the signalling path.

Has somebody shown, absolutely, how this centralized
thing understands an arbitrary routing topology between
the sender and receiver? What happends when it leaves
an AS?

	   Mike