[3372] in linux-net channel archive
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daemon@ATHENA.MIT.EDU (Olaf Titz)
Fri Jun 21 00:45:39 1996
Date: Thu, 20 Jun 96 11:00 +0200
From: olaf@bigred.inka.de (Olaf Titz)
To: submit-linux-dev-net@ratatosk.yggdrasil.com
Newsgroups: linux.dev.net
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From: Olaf Titz <olaf@bigred.inka.de>
Subject: Bandwidth limiter (Re: Binary Driver Issues)
Message-ID: <dtajo2.k5y@bigred.inka.de>
Date: 20 Jun 1996 10:59:57 +0200
References: <199606182119.WAA01978@oberon.di.fc.ul.pt>
<96Jun18.225311edt.106506-7188+5659@vger.rutgers.edu>
Organization: private Linux site, southern Germany
Lines: 34
Mike Kilburn <mike@lserv.conexio.co.za> wrote:
> A traffic shaper - like delay the acks which will slow down the sender
> for one thing. Slowing down the taking of data by the driver on the tx
> side as well.
What has this issue to do with TCP? In theory, all a bandwidth limiter
needs is a slower driver. Devices like SLIP or PPP do the slowdown by
themselves too :-)
This could be implemented as follows: On the sending side, simply
limit the outgoing packet rate. Delay sending of a packet (on the
device level) until the average data rate of the last 4 minutes or so
has gone below the specified limit (leaves much to tweak and
parameterize...) The send queuing does the rest. (What happens when
you stuff the sending side of a SLIP connection? Eventually throws
packets away, I guess.)
The receiving end is trickier. Simply throwing away excess packets
does more hurt than help due to retransmissions. We should implement a
receive queue just like for sending, and dequeuing received packets
should be subject to the delay constraint described above. As long as
the delay is in effect, the receiver should answer each incoming
packet with an ICMP source quench.
Can anyone with TCP and/or Linux driver internals comment whether such
a scheme is feasible, and whether TCP is suited to handle the
situation wrt. acks etc. by itself, given a slow-down network layer?
olaf
--
___ Olaf.Titz@inka.de or @{stud,informatik}.uni-karlsruhe.de ____
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