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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!spool.mu.edu!news.nd.edu!chi-news.cic.net!newsfeeder.sdsu.edu!news.iag.net!news.math.psu.edu!news.cse.psu.edu!uwm.edu!math.ohio-state.edu!howland.reston.ans.net!EU.net!Norway.EU.net!nntp.uio.no!nntp-oslo.UNINETT.no!nntp-trd.UNINETT.no!not-for-mail From: sthaug@nethelp.no (Steinar Haug) Newsgroups: comp.os.linux.networking,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc Subject: Re: Selective Hole NAK (Was: Re: TCP latency) Date: 16 Jul 1996 17:25:04 GMT Organization: Nethelp Consulting, Trondheim, Norway Lines: 41 Message-ID: <4sgj9g$43t@verdi.nethelp.no> References: <4paedl$4bm@engnews2.eng.sun.com> <31DC8EBA.41C67EA6@dyson.iquest.net> <4rlf6i$c5f@linux.cs.helsinki.fi> <31DEA3A3.41C67EA6@dyson.iquest.net> <Du681x.2Gy@kroete2.freinet.de> <31DFEB02.41C67EA6@dyson.iquest.net> <4rpdtn$30b@symiserver2.symantec.com> <x7ohlq78wt.fsf@oberon.di.fc.ul.pt> <Pine.LNX.3.91.960709020017.19115I-100000@reflections.mindspring.com> <x74tnfn35s.fsf@oberon.di.fc.ul.pt> <4s33mj$fv2@innocence.interface-business.de> <x7ivbrddzu.fsf@oberon.di.fc.ul.pt> <SOUVA.96Jul16134620@aibn58.astro.uni-bonn.de> NNTP-Posting-Host: trane.uninett.no In-reply-to: souva@aibn58.astro.uni-bonn.de's message of Tue, 16 Jul 1996 11:46:20 GMT Xref: euryale.cc.adfa.oz.au comp.os.linux.networking:45431 comp.unix.bsd.netbsd.misc:4075 comp.unix.bsd.freebsd.misc:23750 [Ignatios Souvatzis] | TCP itself as a very poor behaviour if you have > 50% packet loss on a | link. By design TCP assumes that links (physical links) have a low packet | | This is true for classical TCP. However, some RFC (was it 1323(?)) | proposes a mechanism to selectively NAK holes in the stream, which | would help. I'm not aware wether this is implemented anywhere. You may find the following of interest. Steinar Haug, Nethelp consulting, sthaug@nethelp.no ---------------------------------------------------------------------- From: Hari Balakrishnan <hari@cs.berkeley.edu> To: end2end-interest@ISI.EDU, tcplw@bsdi.com Subject: TCP SACK implementation available Date: Wed, 10 Jul 1996 13:41:17 -0700 An implementation of the TCP SACK option based on the Jan. '96 IETF Draft (Mathis/Mahdavi/Floyd/Romanow) is available from: ftp://daedalus.cs.berkeley.edu/pub/tcpsack/ The implementation is in the BSD/OS 2.1 kernel and is alpha code. Source modifications to tcpdump (to handle SACKs) are also included, as is a BSDI binary. Some (minor) additions and modifications are planned to the kernel code in the near future. This version of SACK has been in operation for several weeks now at UC Berkeley (as part of the Daedalus project testbed, http://daedalus.cs.berkeley.edu/), and for a few days now for cross-country transfers. Preliminary cross-country experiments performed over the last week across 16-18 Internet hops indicate a throughput improvement of between 30 and 50% on average over Reno, without violating any of the standard congestion control and avoidance mechanisms of TCP. Many thanks to Sally Floyd (LBNL), Srini Seshan (IBM), Vern Paxson (LBNL), and Randy Katz (UCB) for several suggestions, comments and help. Please send any comments, suggestions, bug reports, etc. to hari@cs.berkeley.edu -- Hari Balakrishnan.