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From: David Collier-Brown <davec-b@rogers.com>
To: bloat@lists.bufferbloat.net
Subject: Re: [Bloat] ipspace.net: "QUEUING MECHANISMS IN MODERN	SWITCHES", >       (Jonathan Morton)
Date: Wed, 28 May 2014 13:29:15 -0400	[thread overview]
Message-ID: <53861CEB.8060003@rogers.com> (raw)
In-Reply-To: <mailman.45496.1401291224.1815.bloat@lists.bufferbloat.net>

On 05/28/2014 11:33 AM, Jonathan Morton <chromatix99@gmail.com> wrote
> It's a mathematical truth for any topology that you can reduce to a black box with one or more inputs and one output, which you call a "queue" and which *does
not discard* packets.  Non-discarding queues don't exist in the real
world, of course.
> 
> The intuitive proof is that every time you promote a packet to be transmitted earlier, you must demote one to be transmitted later.  A non-FIFO queue tends to increase the maximum delay and decrease the minimum delay, but the average delay will remain constant.

A niggle: people working in queuing theory* make the simplifying
assumption that queues don't drop. When describing the real world, they
talk of "defections", the scenario where a human arrives at the tail of
the queue and "defects", either to another queue or to the exit door of
the store!

As you might guess, what I find intuitive the IP world finds wrong, and
vice versa.

--dave
[* as opposed, perhaps, to queuing networks (:-)]
-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain



-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain

       reply	other threads:[~2014-05-28 17:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <mailman.45496.1401291224.1815.bloat@lists.bufferbloat.net>
2014-05-28 17:29 ` David Collier-Brown [this message]
2014-05-29  7:28   ` Neil Davies
2014-05-29 14:09   ` Jonathan Morton
2014-05-29 15:36     ` David Collier-Brown

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