From owner-freebsd-net Sat Nov 17 16: 8:11 2001 Delivered-To: freebsd-net@freebsd.org Received: from elvis.mu.org (elvis.mu.org [216.33.66.196]) by hub.freebsd.org (Postfix) with ESMTP id ED79737B416 for ; Sat, 17 Nov 2001 16:08:08 -0800 (PST) Received: by elvis.mu.org (Postfix, from userid 1192) id AF46181D06; Sat, 17 Nov 2001 18:08:03 -0600 (CST) Date: Sat, 17 Nov 2001 18:08:03 -0600 From: Alfred Perlstein To: murthy kn Cc: net@FreeBSD.ORG Subject: Re: TCP Fast Retransmit Message-ID: <20011117180803.D13393@elvis.mu.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from knmurthy30@hotmail.com on Sat, Nov 17, 2001 at 10:24:28PM +0530 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 * murthy kn [011117 10:54] wrote: > Hello, > > 1. Is there any sysctl variable to control the number of > duplicate acks after which the sending TCP gets into a fast > retransmit mode? No, but you can add one like so (i think): Index: tcp_input.c =================================================================== RCS file: /home/ncvs/src/sys/netinet/tcp_input.c,v retrieving revision 1.141 diff -u -r1.141 tcp_input.c --- tcp_input.c 12 Sep 2001 08:37:54 -0000 1.141 +++ tcp_input.c 18 Nov 2001 00:09:51 -0000 @@ -101,6 +101,9 @@ MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry"); static int tcprexmtthresh = 3; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmtthresh, CTLFLAG_RW, + &tcprexmtthresh, 0, "Max duplicate acks before fast rexmit"); + tcp_cc tcp_ccgen; struct tcpstat tcpstat; > 2. If I have a switch that does not support any port aggregation, > and it is connected to a BSD machine with 2 ethernet NICs that have > identical MAC, will the switch forward *each* packet destined to the BSD > machine to both of the NICs. > > 3. Apart from using tcpdump, are there any other tools/ways to analyze the > dynamic behaviour of a BSD stack - like knowing when there have > been retransmits, the state of various buffers in the stack etc. netstat. -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' http://www.morons.org/rants/gpl-harmful.php3 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message