From owner-freebsd-net@FreeBSD.ORG Mon May 22 14:22:12 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6C6C716AB38 for ; Mon, 22 May 2006 14:22:12 +0000 (UTC) (envelope-from mallman@icir.org) Received: from wyvern.icir.org (wyvern.icir.org [192.150.187.14]) by mx1.FreeBSD.org (Postfix) with ESMTP id C50D543D5A for ; Mon, 22 May 2006 14:22:11 +0000 (GMT) (envelope-from mallman@icir.org) Received: from guns.icir.org (adsl-69-222-35-58.dsl.bcvloh.ameritech.net [69.222.35.58]) by wyvern.icir.org (8.12.11/8.12.11) with ESMTP id k4MEMBnw000194; Mon, 22 May 2006 07:22:11 -0700 (PDT) (envelope-from mallman@guns.icir.org) Received: from guns.icir.org (localhost [127.0.0.1]) by guns.icir.org (Postfix) with ESMTP id 2A8FF77AF5C; Mon, 22 May 2006 10:22:10 -0400 (EDT) To: Marcin Jessa , mag@intron.ac, freebsd-net@freebsd.org From: Mark Allman In-Reply-To: Organization: ICSI Center for Internet Research (ICIR) Song-of-the-Day: Jungle Love MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=_bOundary"; micalg=pgp-sha1; protocol="application/pgp-signature" Date: Mon, 22 May 2006 10:22:10 -0400 Sender: mallman@icir.org Message-Id: <20060522142210.2A8FF77AF5C@guns.icir.org> Cc: Subject: Re: How to Quicken TCP Re-transmission? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: mallman@icir.org List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 May 2006 14:22:14 -0000 --=_bOundary Content-Type: text/plain Content-Disposition: inline > > > You can take a look at SCPS - http://www.scps.org/ Their protocol is > > used on lossy links with big latency and packet loss (such as > > satellites) and overcomes shortcomings of TCP. It works with divert > > mechanism of FreeBSD and I ported the tap device part as well to both > > NetBSD / FreeBSD (experimental). > > It's not clear to me that this is going to help. Fundamentally, TCP and > SCTP share the same congestion control response. At 30% packet loss > SCTP ought to be as unusable as TCP. Both consider losses to be > indications of network congestion. > > SCTP does have some things built-in that need to be added onto TCP > (e.g., SACK). So, we could expect more consistent behavior from SCTP > across implementations and platforms. But, in the end the performance > of both is proportional to 1/sqrt(p) where p is the loss rate. So, as > the loss rate increases performance decreases. At 30% you're > essentially cooked no matter which you use. Ugh... Monday mornings... You'll note that what I quoted was about "SCPS" and what I wrote about was "SCTP". These are different. Ignore me. allman --=_bOundary Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQFEcckSWyrrWs4yIs4RAnr/AJ0UfzYCV1aI+b8LtqLk+H4G2GvV3gCcDr/r Tp7JKez5J8y8i66/u+beXEA= =USBM -----END PGP SIGNATURE----- --=_bOundary--