From owner-freebsd-net Mon Nov 26 13: 7: 8 2001 Delivered-To: freebsd-net@freebsd.org Received: from boreas.isi.edu (boreas.isi.edu [128.9.160.161]) by hub.freebsd.org (Postfix) with ESMTP id 4D89437B41B for ; Mon, 26 Nov 2001 13:07:02 -0800 (PST) Received: from isi.edu (nlpxnd1jsu3riexh@hbo.isi.edu [128.9.160.75]) by boreas.isi.edu (8.11.6/8.11.2) with ESMTP id fAQL6xN20261; Mon, 26 Nov 2001 13:06:59 -0800 (PST) Message-ID: <3C02AEF3.3000502@isi.edu> Date: Mon, 26 Nov 2001 13:06:59 -0800 From: Lars Eggert User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:0.9.6) Gecko/20011121 X-Accept-Language: en, de MIME-Version: 1.0 To: Jonathan Lemon Cc: Garrett Wollman , net@FreeBSD.ORG Subject: Re: decreasing TIME_WAIT duration(T/TCP?) References: <200111261443.fAQEhu185094@prism.flugsvamp.com> <200111261947.fAQJl0321324@khavrinen.lcs.mit.edu> <20011126141909.N75389@prism.flugsvamp.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit 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 Jonathan Lemon wrote: > As you said, there is no way to reliably calculate this value, since the > delay is theortically unbounded; in fact RFC 793 sets it at 120 seconds. > > However, my assertion is that in most cases, the true MSL for segments > on a given connection will tend to be tied to some multiple of the RTT; > that is, there exists a strong correlation between the two. While I agree that the average "segment lifetime" of a given connection is probably on the same order of magnitude than the RTT, this does not have any impact on the MAXIMUM segment lifetime: it's an Internet-wide upper bound. Even for connections with millisecond RTTs, packets can be delayed for seconds or longer due to routing glitches. The original poster wanted to shorten the MSL to avoid accumulating TIME WAITs at the server. There are better techniques for that, see for example Ted Faber's paper in INFOCOM '99 (http://www.isi.edu/~faber/pubs.html). Lars -- Lars Eggert Information Sciences Institute http://www.isi.edu/larse/ University of Southern California To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message