From owner-freebsd-net Thu Nov 29 22:50:12 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 7ADF437B419; Thu, 29 Nov 2001 22:50:07 -0800 (PST) Received: (from jlemon@localhost) by prism.flugsvamp.com (8.11.0/8.11.0) id fAU6l9K60404; Fri, 30 Nov 2001 00:47:09 -0600 (CST) (envelope-from jlemon) Date: Fri, 30 Nov 2001 00:47:09 -0600 (CST) From: Jonathan Lemon Message-Id: <200111300647.fAU6l9K60404@prism.flugsvamp.com> To: bmah@FreeBSD.ORG, net@FreeBSD.ORG Subject: Re: TCP anomalies (was Re: FreeBSD performing worse than Linux?) X-Newsgroups: local.mail.freebsd-net In-Reply-To: References: 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: >-=-=-=-=-=- >test4 was the only trace I looked at. One thing that caught my eye is >that the receiver seems to be sending a bunch of dupacks (in some cases, >many more than needed to trigger fast retransmit) but no retransmit >happens. In *most* cases, the receiver somehow gets the missing data >because you can later see it acking later sequence numbers. The first >place I saw this was at :41.504152. > >This looks a little odd, but it *could* be explained by data segments >getting misordered somewhere and the dupacks getting lost. > >Another place to look is the large number of consecutive dupacks >starting around :41.978767. I don't know what's happening here, but >after a long time (about a second?!?) the sender finally gives up and >sends the receiver what it wants. Yes, I think that area (I was looking at it too) provides a fairly good illustration that fast retransmits are broken. The transmit at 14:01:42.969338 appears to be the retransmit timer finally kicking in. I wonder if we can figure out which -RELEASE this started happening in. -- Jonathan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message