Date: Sun, 26 Aug 2001 23:04:50 -0400 (EDT) From: Mike Silbersack <silby@silby.com> To: singh <singh@pdx.edu> Cc: Dave Zarzycki <zarzycki@FreeBSD.ORG>, Alfred Perlstein <bright@mu.org>, <freebsd-net@FreeBSD.ORG> Subject: Re: RFC: SACK/FACK patch port to Current Message-ID: <Pine.BSF.4.30.0108262259080.72039-100000@niwun.pair.com> In-Reply-To: <998543289.3b848fba02294@webmail.pdx.edu>
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On Wed, 22 Aug 2001, singh wrote: > I even observed that FreeBSD4.3 adopts to NewReno algorith which is a > suggestion in RFC-2582 (which talks about NewReno, SACK and FACK), for clients > who can not have SACK/FACK, new reno will alleviate the problem of duplicate > acks in Fast Recovery stage and partial ack is a better solution as comapre to > reno algorithm. Ok, I looked over the patch more, as well as the RFCs. Basic SACK support seems straightforward according to the RFCs, but FACK is a bit more complex. From what I can tell, FACK isn't a tcp feature as much as a retransmission scheme. This scheme, in turn, has been updated and is now called "rate halving". Is the FACK implementation in this patch the old version, or the rate-halving version? Also, does FACK spill over into non-SACKed connections? I couldn't tell from a quick readthrough. I've also noticed that while SACK is sysctl disableable, FACK is not. A sysctl for FACK should be added as well so that we can enable/disable it at will (as can be done with newreno.) Thanks, Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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