Date: Fri, 30 Nov 2001 00:47:09 -0600 (CST) From: Jonathan Lemon <jlemon@flugsvamp.com> To: bmah@FreeBSD.ORG, net@FreeBSD.ORG Subject: Re: TCP anomalies (was Re: FreeBSD performing worse than Linux?) Message-ID: <200111300647.fAU6l9K60404@prism.flugsvamp.com> In-Reply-To: <local.mail.freebsd-net/200111300518.fAU5IXx11078@c527597-a.cstvl1.sfba.home.com> References: <local.mail.freebsd-net/20011128102241.6887B380A@overcee.netplex.com.au> <local.mail.freebsd-net/20011128112006.195983808@overcee.netplex.com.au> <local.mail.freebsd-net/20011129105321.C74413@monorchid.lemis.com> <local.mail.freebsd-net/200111290113.fAT1DnH04474@khavrinen.lcs.mit.edu>
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In article <local.mail.freebsd-net/200111300518.fAU5IXx11078@c527597-a.cstvl1.sfba.home.com> 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
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