From owner-freebsd-net Sat Nov 17 10:21:54 2001 Delivered-To: freebsd-net@freebsd.org Received: from prism.flugsvamp.com (cb58709-a.mdsn1.wi.home.com [24.17.241.9]) by hub.freebsd.org (Postfix) with ESMTP id 0306E37B405 for ; Sat, 17 Nov 2001 10:21:50 -0800 (PST) Received: (from jlemon@localhost) by prism.flugsvamp.com (8.11.0/8.11.0) id fAHIKBw94562; Sat, 17 Nov 2001 12:20:11 -0600 (CST) (envelope-from jlemon) Date: Sat, 17 Nov 2001 12:20:11 -0600 (CST) From: Jonathan Lemon Message-Id: <200111171820.fAHIKBw94562@prism.flugsvamp.com> To: knmurthy30@hotmail.com, net@freebsd.org Subject: Re: TCP Fast Retransmit X-Newsgroups: local.mail.freebsd-net In-Reply-To: Organization: Cc: 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 In article you write: >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 the current limit is in tcp_input.c: static int tcprexmtthresh = 3; so you can easily change this. >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. Unlikely. The switch will probably allow only one mac->port mapping. >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. I like tcptrace, but that is an external view. You could try turning on the TCPDEBUG #define, although I'm not sure how useful it would be. -- Jonathan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message