From owner-cvs-all Wed Jul 17 19:28:47 2002 Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D1FBD37B400; Wed, 17 Jul 2002 19:28:38 -0700 (PDT) Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8226E43E4A; Wed, 17 Jul 2002 19:28:38 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: from apollo.backplane.com (localhost [127.0.0.1]) by apollo.backplane.com (8.12.5/8.12.4) with ESMTP id g6I2ScCV004824; Wed, 17 Jul 2002 19:28:38 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.12.5/8.12.4/Submit) id g6I2Scpv004823; Wed, 17 Jul 2002 19:28:38 -0700 (PDT) (envelope-from dillon) Date: Wed, 17 Jul 2002 19:28:38 -0700 (PDT) From: Matthew Dillon Message-Id: <200207180228.g6I2Scpv004823@apollo.backplane.com> To: Garrett Wollman Cc: cvs-committers@FreeBSD.ORG, Subject: Re: cvs commit: src/sys/netinet tcp_timer.h References: <20020717185653.C82638-100000@patrocles.silby.com> <200207180102.g6I129Gw004350@apollo.backplane.com> <200207180206.g6I266ma000510@khavrinen.lcs.mit.edu> Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG : :< said: : :> Actually, :> I think the one second minimum is absurd anyway, so no, I am not :> going to back it out. : :The standard says one second, period. It's not your choice to make. : :-GAWollman I've looked through five RFCs. I have been unable to locate any lower bound requirement fro the retransmission timeout. The best I've found is in RFC1122, 4.2.3.1: The recommended upper and lower bounds on the RTO are known to be inadequate on large internets. The lower bound SHOULD be measured in fractions of a second (to accommodate high speed LANs) and the upper bound should be 2*MSL, i.e., 240 seconds. All the other references I've found... New Reno and the two congestion control RFCs (one being the fast-retransmit RFC) simply state something on the order of 2*RTT or something similar. RFC793 has an eample of an RTO timeout calculation where it says "where UBOUND is an upper bound on the timeout (e.g., 1 minute), LBOUND is a lower bound on the timeout (e.g., 1 second), ALPHA is a smoothing factor (e.g., .8 to .9), and BETA is a delay variance factor (e.g., 1.3 to 2.0)." This is obviously NOT a requirement of any sort, and besides it is in RFC793... an extremely old RFC (1981). -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message