Subject: Re: Ambiguities in QoS path management

From: [email-masked]
Date: Tue, 5 Aug 97 09:01:47 PDT

*> 
  *> I would expect RSVP to do the signaling function to establish and maintain
  *> the path as computed by routing.  I would expect RSVP to discover (via
  *> normal path failure mechanisms) if there is an infrastructure failure and
  *> notify routing.  Similarly, I would expect routing to discover that

Tony,

RSVP has no up/down protocol or other way to determine path failure;
it assumes routing does.

Bob

  *> particular paths are no longer appropriate and notify RSVP that certain
  *> paths need revision.
  *> 
  *> Tony
  *> 
  *>

---

From: [email-masked] (Noel Chiappa)
Date: Tue, 5 Aug 97 17:18:42 -0400

From: Roch Guerin <[email-masked]>

    there is some flexibility as far as function placement is concerned,
    i.e., where is the relevant (path) information kept and which component
    is responsible for identifying events that are capable of triggering
    changes to an existing path ... In particular, one can place some of
    these responsibilities with either RSVP or routing.

I'd like to encourage people to stop thinking of "routing" as a monolithic
entity, and start thinking of it as a number of different subsystems (e.g.
data distribution, path selection, etc), the interaction between which is
visible, and accessible, to other subsystems (such as resource reservation).

We don't yet have such a routing architecture, it's true (although I feel
certain that one day we will), but I think it's useful to start *thinking* in
this model because:

- i) it makes it easier and clearer to understand what's going on, and
- ii) it's easier to where we are limited by fundamentals, and where the limits
  are simply artifacts of an old routing architecture which was never intended
  to support this kind of functionality.

The current status of the RSVP-Routing interaction reminds me of CIDR - well
done, within the limits set by the past. However, such approaches reach a
limit fairly quickly - and the architectural approach of treating routing as
monolith is one such.

	Noel