Date: Wed, 10 Mar 2004 23:08:00 +0200 From: Petri Helenius <pete@he.iki.fi> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: Kevin Oberman <oberman@es.net> Subject: Re: Who wants SACK? (Re: was My planned work on networking stack) Message-ID: <404F83B0.7020803@he.iki.fi> In-Reply-To: <20040310192255.GD14892@Odin.AC.HMC.Edu> References: <20040309214205.3EE2D5D07@ptavv.es.net> <20040309160821.P705@odysseus.silby.com> <20040310123237.V61186@beagle.fokus.fraunhofer.de> <20040310154139.GA14892@Odin.AC.HMC.Edu> <404F40EB.6040702@he.iki.fi> <20040310192255.GD14892@Odin.AC.HMC.Edu>
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Brooks Davis wrote: >The problem is that the BER of a typical optical link is high enough >that the link will almost certantly discard at least one packet before >you get out of slow-start and once that happens it, AIMK means it take >hours or even days to get back up to the top even assuming you don't >lose further packets. This isn't a problem for most people, but it's >definalty a problem for the HPC community. > > > BER is usually combatted with technologies which embed redundant bits into the datastream so an occasional bit error does not take out a packet. In conjuction of 10GbE this would probably mean G.709. I would be happy to learn whether the typical link has BER of 10E-15 or 10E-12 and how fast retransmit plays in the picture of losing a bit every ten minutes or so. Pete
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