Date: Wed, 16 Feb 2005 18:30:46 -0800 From: Julian Elischer <julian@elischer.org> To: net@freebsd.org Subject: Re: odd tcp trace. Message-ID: <421401D6.3040700@elischer.org> In-Reply-To: <20050217021554.GD15240@yahoo-inc.com> References: <4213FD97.7000708@elischer.org> <20050217021554.GD15240@yahoo-inc.com>
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jayanth wrote: >tcp large windows must have been negotiated which allows for window sizes > 32k. >Look at the SYN packet and see if that is the case. > yes, S 1555577485:1555577485(0) win 65535 <mss 1460,nop,wscale 1,nop,nop> (DF) S 2834868684:2834868684(0) ack 1555577486 win 65535 <mss 1460,nop,wscale 2,nop,nop,> (DF) 19:53:49.692581 machineA.2293 > machineB.49177: . ack 1 win 33304 <nop,nop> (DF) 19:53:49.692610 machineB.49177 > machineA.2293: . ack 1 win 32942 <nop,nop> (DF) but: shouldn't tcpdump already be taking the scale into account? I guess not, in which case the window is 64K but, then why did it stop sending when the outstanding data reached 33057? > >jayanth > >Julian Elischer (julian@elischer.org) wrote: > > >>This is a conversation between 2 FreeBSD 4.8 machines. >> >>Does anyone else worry about what is going on here regarding packets >>sent and the received window? >> >>only odd setting here is that the slowstart flightsize was set to 30 >>(it was the only machine using this high latency link) (400mSec rtt but >>lots of bandwidth) >> >>19:53:49.694030 machineA.49177 > machineB.2293: . 28713:30161(1448) ack >>1 win 32942 >>19:53:49.694039 machineA.49177 > machineB.2293: . 30161:31609(1448) ack >>1 win 32942 >>19:53:49.694050 machineA.49177 > machineB.2293: . 31609:33057(1448) ack >>1 win 32942 >> sender delays here when outstanding data reached ~ 32K. it has NOT reached 30 packets yet.. >>19:53:50.069090 machineB.2293 > machineA.49177: . ack 2897 win 32580 >>19:53:50.069111 machineA.49177 > machineB.2293: . 33057:34505(1448) ack >>1 win 32942 >>19:53:50.069120 machineA.49177 > machineB.2293: . 34505:35953(1448) ack >>1 win 32942 >>19:53:50.069131 machineA.49177 > machineB.2293: . 35953:37401(1448) ack >>1 win 32942 >>19:53:50.069140 machineA.49177 > machineB.2293: . 37401:38849(1448) ack >>1 win 32942 >>19:53:50.069189 machineA.49177 > machineB.2293: . 38849:40297(1448) ack >>1 win 32942 >>19:53:50.069199 machineA.49177 > machineB.2293: . 40297:41745(1448) ack >>1 win 32942 >>19:53:50.069209 machineA.49177 > machineB.2293: . 41745:43193(1448) ack >>1 win 32942 >>19:53:50.069218 machineA.49177 > machineB.2293: . 43193:44641(1448) ack >>1 win 32942 >>19:53:50.069227 machineA.49177 > machineB.2293: . 44641:46089(1448) ack >>1 win 32942 >>19:53:50.069236 machineA.49177 > machineB.2293: . 46089:47537(1448) ack >>1 win 32942 >>19:53:50.069245 machineA.49177 > machineB.2293: . 47537:48985(1448) ack >>1 win 32942 >> >>accrding to my calculations.. machine A should not fell it ok to send >>any packets beyond >>sequence # 2897 + 32580 >> >>yet it goes ahead and sends data up to 48985 which is WAY out of range.. >> >> >>_______________________________________________ >>freebsd-net@freebsd.org mailing list >>http://lists.freebsd.org/mailman/listinfo/freebsd-net >>To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >> >> >> >>
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