From owner-freebsd-net Sun Aug 26 20: 4:55 2001 Delivered-To: freebsd-net@freebsd.org Received: from niwun.pair.com (niwun.pair.com [209.68.2.70]) by hub.freebsd.org (Postfix) with SMTP id 6B89137B40C for ; Sun, 26 Aug 2001 20:04:51 -0700 (PDT) (envelope-from silby@silby.com) Received: (qmail 73147 invoked by uid 3193); 27 Aug 2001 03:04:50 -0000 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 27 Aug 2001 03:04:50 -0000 Date: Sun, 26 Aug 2001 23:04:50 -0400 (EDT) From: Mike Silbersack X-Sender: To: singh Cc: Dave Zarzycki , Alfred Perlstein , Subject: Re: RFC: SACK/FACK patch port to Current In-Reply-To: <998543289.3b848fba02294@webmail.pdx.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org 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