Subject: RE: [Diffserv] Intuitive EF ?

From: Bill Courtney <[email-masked]>
Date: Wed, 26 Jul 2000 11:42:01 -0700

> 
> > >Re-analyzing sections 1.2.1 and 1.2.2 using my interpretation of
> > >"average" results in everything working out fine (apparently).
> 
> If you pick up any arbitrary interval then of course definition is not
> valid. But you do agree that if the start time is always fixed to be
> the moment the first bit of an EF packet is transmitted, and the stop
> time is arbitrary and greater than MTU/C beyond the start time, it
> fixes the problem in the 1.2.1 in your draft.
> 
>

You will also have to add some condition about how long the router can
delay after the EF packet arrives before the router sends the first bit 
of that packet. I think you'll need at least a little slack for internal 
delay. This pushes us back toward the situation where there is time when 
no EF bits are forwarded both before and after each EF packet is forwarded. 
While this is not as wide-open as "any arbitrary interval", it is
definitely a step in that direction. Nonetheless, resolution of this
initial latency may be straight-forward.

Brijesh, I think that you are on a promising line of thought.

Bill Courtney
TRW, Network System Engineering
-----

Only the mediocre person is always at his best.
                                             Tom & Ray Magliozzi

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From: Grenville Armitage <[email-masked]>
Date: Wed, 26 Jul 2000 12:12:06 -0700

Bill Courtney wrote:
	[..]
> of that packet.

I'm not sure I understand the need for this constraint. Provided the
delay is relatively constant there isn't much more that EF requires.
(In so far as EF aims to constrain jitter, but says nothing about
whether EF-compliant routers can add 10ms of latency per hop, or
1ms, or 100us, or whatever just so long as it doesnt fluctuate too
much, aka jitter.)

cheers,
gja
________________________________________________________________________
Grenville Armitage                    http://members.home.net/garmitage/
Bell Labs Research Silicon Valley