Groups > comp.os.linux.networking > #276

Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised

From	Mark Hobley <markhobley@yahoo.donottypethisbit.co>
Newsgroups	comp.os.linux.networking
Subject	Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised
Date	2011-05-21 14:58 +0000
Organization	A noiseless patient Spider
Message-ID	<ir8jui$l3k$1@dont-email.me> (permalink)

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I am upgraded my Debian system to experimental kernel 2.6.39-rc7. This has
caused an old network problem to reoccur, which I believe is related to the
network Maximum Segment Size that my ISP can convey.

On startup of my computer, I issue a command to clamp the size of all
externally bound traffic (destined for routing via the default gateway at
10.0.0.1) as follows:

ip route change default via 10.0.0.1 mtu lock 1412

Where 1412 is the maximum transmission unit for my ISP (Three mobile).
I now attempt to post a usenet article, and the newsreader hangs.

I have used tcpdump to examine the communications, and here is the output:

18: Flags [S.], seq 3385954279, ack 3902988975, win 5792, options [mss 1380,sackOK,TS val 140346418 ecr 47079743,nop,wscale 7], length 0
03:40:13.539947 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47079880 ecr 140346418], length 0
03:40:14.079843 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [P.], seq 1:107, ack 1, win 46, options [nop,nop,TS val 140346550 ecr 47079880], length 106
03:40:14.079914 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], ack 107, win 457, options [nop,nop,TS val 47080015 ecr 140346550], length 0
03:40:14.080345 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [P.], seq 1:23, ack 107, win 457, options [nop,nop,TS val 47080016 ecr 140346550], length 22
03:40:14.829571 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [.], ack 23, win 46, options [nop,nop,TS val 140346745 ecr 47080016], length 0
03:40:14.869553 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [P.], seq 107:127, ack 23, win 46, options [nop,nop,TS val 140346745 ecr 47080016], length 20
03:40:14.870604 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [P.], seq 23:47, ack 127, win 457, options [nop,nop,TS val 47080213 ecr 140346745], length 24
03:40:15.509493 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [.], ack 47, win 46, options [nop,nop,TS val 140346913 ecr 47080213], length 0
03:40:15.759474 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [P.], seq 127:157, ack 47, win 46, options [nop,nop,TS val 140346967 ecr 47080213], length 30
03:40:15.759754 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [P.], seq 47:60, ack 157, win 457, options [nop,nop,TS val 47080435 ecr 140346967], length 13
03:40:16.300519 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [.], ack 60, win 46, options [nop,nop,TS val 140347111 ecr 47080435], length 0
03:40:16.339579 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [P.], seq 157:263, ack 60, win 46, options [nop,nop,TS val 140347111 ecr 47080435], length 106
03:40:16.340742 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [P.], seq 60:66, ack 263, win 457, options [nop,nop,TS val 47080581 ecr 140347111], length 6
03:40:16.941302 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [P.], seq 263:324, ack 66, win 46, options [nop,nop,TS val 140347268 ecr 47080581], length 61
03:40:16.941635 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47080731 ecr 140347268], length 1368
03:40:16.941686 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [P.], seq 1434:2113, ack 324, win 457, options [nop,nop,TS val 47080731 ecr 140347268], length 679
03:40:16.941731 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 2113:3481, ack 324, win 457, options [nop,nop,TS val 47080731 ecr 140347268], length 1368
03:40:16.941995 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 3481:4849, ack 324, win 457, options [nop,nop,TS val 47080731 ecr 140347268], length 1368
03:40:18.168057 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [P.], seq 263:324, ack 66, win 46, options [nop,nop,TS val 140347601 ecr 47080581], length 61
03:40:18.168130 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], ack 324, win 457, options [nop,nop,TS val 47081037 ecr 140347601,nop,nop,sack 1 {263:324}], length 0
03:40:18.388264 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [.], ack 66, win 46, options [nop,nop,TS val 140347656 ecr 47080581,nop,nop,sack 1 {108444702:108445381}], length 0
03:40:18.544109 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47081132 ecr 140347656], length 1368
03:40:21.752110 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47081934 ecr 140347656], length 1368
03:40:28.160112 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47083536 ecr 140347656], length 1368
03:40:40.992116 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47086744 ecr 140347656], length 1368
03:40:46.942740 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [FP.], seq 4849:5371, ack 324, win 457, options [nop,nop,TS val 47088231 ecr 140347656], length 522
03:40:48.745614 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [S], seq 185692436, win 14600, options [mss 1460,sackOK,TS val 47088682 ecr 0,nop,wscale 5], length 0
03:40:48.745939 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [.], ack 66, win 46, options [nop,nop,TS val 140355243 ecr 47080581,nop,nop,sack 2 {108448117:108448640}{108444702:108445381}], length 0
03:40:48.863069 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [S.], seq 3936843225, ack 185692437, win 5792, options [mss 1380,sackOK,TS val 140355273 ecr 47088682,nop,wscale 7], length 0
03:40:48.863153 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47088711 ecr 140355273], length 0
03:40:48.973427 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [P.], seq 1:107, ack 1, win 46, options [nop,nop,TS val 140355304 ecr 47088711], length 106
03:40:48.973497 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], ack 107, win 457, options [nop,nop,TS val 47088739 ecr 140355304], length 0
03:40:48.973831 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [P.], seq 1:23, ack 107, win 457, options [nop,nop,TS val 47088739 ecr 140355304], length 22
03:40:49.103319 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [.], ack 23, win 46, options [nop,nop,TS val 140355332 ecr 47088739], length 0
03:40:49.104431 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [P.], seq 107:127, ack 23, win 46, options [nop,nop,TS val 140355332 ecr 47088739], length 20
03:40:49.104729 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [P.], seq 23:47, ack 127, win 457, options [nop,nop,TS val 47088772 ecr 140355332], length 24
03:40:49.263060 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [.], ack 47, win 46, options [nop,nop,TS val 140355373 ecr 47088772], length 0
03:40:49.443101 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [P.], seq 127:157, ack 47, win 46, options [nop,nop,TS val 140355420 ecr 47088772], length 30
03:40:49.443438 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [P.], seq 47:60, ack 157, win 457, options [nop,nop,TS val 47088856 ecr 140355420], length 13
03:40:49.553169 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [.], ack 60, win 46, options [nop,nop,TS val 140355447 ecr 47088856], length 0
03:40:49.553943 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [P.], seq 157:263, ack 60, win 46, options [nop,nop,TS val 140355447 ecr 47088856], length 106
03:40:49.554864 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [P.], seq 60:66, ack 263, win 457, options [nop,nop,TS val 47088884 ecr 140355447], length 6
03:40:49.663214 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [P.], seq 263:324, ack 66, win 46, options [nop,nop,TS val 140355475 ecr 47088884], length 61
03:40:49.663616 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47088911 ecr 140355475], length 1368
03:40:49.663751 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [P.], seq 1434:2113, ack 324, win 457, options [nop,nop,TS val 47088911 ecr 140355475], length 679
03:40:49.663820 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 2113:3481, ack 324, win 457, options [nop,nop,TS val 47088911 ecr 140355475], length 1368
03:40:49.663883 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 3481:4849, ack 324, win 457, options [nop,nop,TS val 47088911 ecr 140355475], length 1368
03:40:49.833205 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [.], ack 66, win 46, options [nop,nop,TS val 140355515 ecr 47088884,nop,nop,sack 1 {1136656415:1136657094}], length 0
03:40:51.120106 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47089276 ecr 140355515], length 1368
03:40:54.040109 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47090006 ecr 140355515], length 1368
03:40:59.872112 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47091464 ecr 140355515], length 1368
03:41:06.624110 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47093152 ecr 140355243], length 1368
03:41:11.552115 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47094384 ecr 140355515], length 1368
03:41:19.664368 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [FP.], seq 4849:5371, ack 324, win 457, options [nop,nop,TS val 47096412 ecr 140355515], length 522
03:41:21.333831 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [S], seq 693658575, win 14600, options [mss 1460,sackOK,TS val 47096829 ecr 0,nop,wscale 5], length 0
03:41:21.352674 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52196: Flags [.], ack 66, win 46, options [nop,nop,TS val 140363396 ecr 47088884,nop,nop,sack 2 {1136659830:1136660353}{1136656415:1136657094}], length 0
03:41:21.453043 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [S.], seq 156904658, ack 693658576, win 5792, options [mss 1380,sackOK,TS val 140363421 ecr 47096829,nop,wscale 7], length 0
03:41:21.453127 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47096859 ecr 140363421], length 0
03:41:21.572897 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [P.], seq 1:107, ack 1, win 46, options [nop,nop,TS val 140363451 ecr 47096859], length 106
03:41:21.572967 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], ack 107, win 457, options [nop,nop,TS val 47096889 ecr 140363451], length 0
03:41:21.573318 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [P.], seq 1:23, ack 107, win 457, options [nop,nop,TS val 47096889 ecr 140363451], length 22
03:41:21.702709 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [.], ack 23, win 46, options [nop,nop,TS val 140363483 ecr 47096889], length 0
03:41:21.703423 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [P.], seq 107:127, ack 23, win 46, options [nop,nop,TS val 140363483 ecr 47096889], length 20
03:41:21.703722 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [P.], seq 23:47, ack 127, win 457, options [nop,nop,TS val 47096921 ecr 140363483], length 24
03:41:21.862808 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [.], ack 47, win 46, options [nop,nop,TS val 140363523 ecr 47096921], length 0
03:41:22.062740 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [P.], seq 127:157, ack 47, win 46, options [nop,nop,TS val 140363573 ecr 47096921], length 30
03:41:22.063102 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [P.], seq 47:60, ack 157, win 457, options [nop,nop,TS val 47097011 ecr 140363573], length 13
03:41:22.182911 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [.], ack 60, win 46, options [nop,nop,TS val 140363603 ecr 47097011], length 0
03:41:22.183880 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [P.], seq 157:263, ack 60, win 46, options [nop,nop,TS val 140363603 ecr 47097011], length 106
03:41:22.184818 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [P.], seq 60:66, ack 263, win 457, options [nop,nop,TS val 47097042 ecr 140363603], length 6
03:41:22.302817 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [P.], seq 263:324, ack 66, win 46, options [nop,nop,TS val 140363633 ecr 47097042], length 61
03:41:22.303201 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47097071 ecr 140363633], length 1368
03:41:22.303250 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [P.], seq 1434:2113, ack 324, win 457, options [nop,nop,TS val 47097071 ecr 140363633], length 679
03:41:22.303293 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 2113:3481, ack 324, win 457, options [nop,nop,TS val 47097071 ecr 140363633], length 1368
03:41:22.303467 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 3481:4849, ack 324, win 457, options [nop,nop,TS val 47097071 ecr 140363633], length 1368
03:41:22.472809 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [.], ack 66, win 46, options [nop,nop,TS val 140363676 ecr 47097042,nop,nop,sack 1 {3773242939:3773243618}], length 0
03:41:23.748109 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47097433 ecr 140363676], length 1368
03:41:26.640110 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47098156 ecr 140363676], length 1368
03:41:32.432107 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47099604 ecr 140363676], length 1368
03:41:34.912108 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47100224 ecr 140363396], length 1368
03:41:44.000113 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47102496 ecr 140363676], length 1368
03:41:52.304227 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [FP.], seq 4849:5371, ack 324, win 457, options [nop,nop,TS val 47104572 ecr 140363676], length 522
03:41:54.123370 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [S], seq 1215827121, win 14600, options [mss 1460,sackOK,TS val 47105026 ecr 0,nop,wscale 5], length 0
03:41:54.132221 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52197: Flags [.], ack 66, win 46, options [nop,nop,TS val 140371591 ecr 47097042,nop,nop,sack 2 {3773246354:3773246877}{3773242939:3773243618}], length 0
03:41:54.242321 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [S.], seq 664320455, ack 1215827122, win 5792, options [mss 1380,sackOK,TS val 140371618 ecr 47105026,nop,wscale 7], length 0
03:41:54.242407 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47105056 ecr 140371618], length 0
03:41:54.372280 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [P.], seq 1:107, ack 1, win 46, options [nop,nop,TS val 140371649 ecr 47105056], length 106
03:41:54.372351 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], ack 107, win 457, options [nop,nop,TS val 47105089 ecr 140371649], length 0
03:41:54.372683 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [P.], seq 1:23, ack 107, win 457, options [nop,nop,TS val 47105089 ecr 140371649], length 22
03:41:54.492582 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [.], ack 23, win 46, options [nop,nop,TS val 140371680 ecr 47105089], length 0
03:41:54.493552 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [P.], seq 107:127, ack 23, win 46, options [nop,nop,TS val 140371680 ecr 47105089], length 20
03:41:54.493840 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [P.], seq 23:47, ack 127, win 457, options [nop,nop,TS val 47105119 ecr 140371680], length 24
03:41:54.652325 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [.], ack 47, win 46, options [nop,nop,TS val 140371721 ecr 47105119], length 0
03:41:54.832400 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [P.], seq 127:157, ack 47, win 46, options [nop,nop,TS val 140371767 ecr 47105119], length 30
03:41:54.832738 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [P.], seq 47:60, ack 157, win 457, options [nop,nop,TS val 47105204 ecr 140371767], length 13
03:41:54.952403 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [.], ack 60, win 46, options [nop,nop,TS val 140371796 ecr 47105204], length 0
03:41:54.953236 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [P.], seq 157:263, ack 60, win 46, options [nop,nop,TS val 140371796 ecr 47105204], length 106
03:41:54.954135 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [P.], seq 60:66, ack 263, win 457, options [nop,nop,TS val 47105234 ecr 140371796], length 6
03:41:55.072439 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [P.], seq 263:324, ack 66, win 46, options [nop,nop,TS val 140371826 ecr 47105234], length 61
03:41:55.072935 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47105264 ecr 140371826], length 1368
03:41:55.072986 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [P.], seq 1434:2113, ack 324, win 457, options [nop,nop,TS val 47105264 ecr 140371826], length 679
03:41:55.073028 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 2113:3481, ack 324, win 457, options [nop,nop,TS val 47105264 ecr 140371826], length 1368
03:41:55.073074 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 3481:4849, ack 324, win 457, options [nop,nop,TS val 47105264 ecr 140371826], length 1368
03:41:55.242762 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [.], ack 66, win 46, options [nop,nop,TS val 140371868 ecr 47105234,nop,nop,sack 1 {3715427543:3715428222}], length 0
03:41:56.524109 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47105627 ecr 140371868], length 1368
03:41:57.952132 IP venus.markhobley.yi.org.51218 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47105984 ecr 140355243], length 1368
03:41:59.424110 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47106352 ecr 140371868], length 1368
03:42:05.232112 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47107804 ecr 140371868], length 1368
03:42:07.168110 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47108288 ecr 140371591], length 1368
03:42:16.832117 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47110704 ecr 140371868], length 1368
03:42:21.632113 IP venus.markhobley.yi.org.52196 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47111904 ecr 140363396], length 1368
03:42:25.093656 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [FP.], seq 4849:5371, ack 324, win 457, options [nop,nop,TS val 47112769 ecr 140371868], length 522
03:42:26.863526 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [S], seq 1725633662, win 14600, options [mss 1460,sackOK,TS val 47113211 ecr 0,nop,wscale 5], length 0
03:42:26.872096 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52198: Flags [.], ack 66, win 46, options [nop,nop,TS val 140379776 ecr 47105234,nop,nop,sack 2 {3715430958:3715431481}{3715427543:3715428222}], length 0
03:42:26.982276 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [S.], seq 1178329563, ack 1725633663, win 5792, options [mss 1380,sackOK,TS val 140379803 ecr 47113211,nop,wscale 7], length 0
03:42:26.982362 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47113241 ecr 140379803], length 0
03:42:27.102306 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [P.], seq 1:107, ack 1, win 46, options [nop,nop,TS val 140379834 ecr 47113241], length 106
03:42:27.102379 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], ack 107, win 457, options [nop,nop,TS val 47113271 ecr 140379834], length 0
03:42:27.102731 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [P.], seq 1:23, ack 107, win 457, options [nop,nop,TS val 47113271 ecr 140379834], length 22
03:42:27.232157 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [.], ack 23, win 46, options [nop,nop,TS val 140379866 ecr 47113271], length 0
03:42:27.232883 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [P.], seq 107:127, ack 23, win 46, options [nop,nop,TS val 140379866 ecr 47113271], length 20
03:42:27.233161 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [P.], seq 23:47, ack 127, win 457, options [nop,nop,TS val 47113304 ecr 140379866], length 24
03:42:27.402170 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [.], ack 47, win 46, options [nop,nop,TS val 140379911 ecr 47113304], length 0
03:42:27.612972 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [P.], seq 127:157, ack 47, win 46, options [nop,nop,TS val 140379962 ecr 47113304], length 30
03:42:27.613330 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [P.], seq 47:60, ack 157, win 457, options [nop,nop,TS val 47113399 ecr 140379962], length 13
03:42:27.732360 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [.], ack 60, win 46, options [nop,nop,TS val 140379991 ecr 47113399], length 0
03:42:27.733341 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [P.], seq 157:263, ack 60, win 46, options [nop,nop,TS val 140379991 ecr 47113399], length 106
03:42:27.734237 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [P.], seq 60:66, ack 263, win 457, options [nop,nop,TS val 47113429 ecr 140379991], length 6
03:42:27.842217 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [P.], seq 263:324, ack 66, win 46, options [nop,nop,TS val 140380020 ecr 47113429], length 61
03:42:27.842599 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47113456 ecr 140380020], length 1368
03:42:27.842626 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [P.], seq 1434:2113, ack 324, win 457, options [nop,nop,TS val 47113456 ecr 140380020], length 679
03:42:27.842652 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 2113:3481, ack 324, win 457, options [nop,nop,TS val 47113456 ecr 140380020], length 1368
03:42:27.842687 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 3481:4849, ack 324, win 457, options [nop,nop,TS val 47113456 ecr 140380020], length 1368
03:42:28.012253 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [.], ack 66, win 46, options [nop,nop,TS val 140380062 ecr 47113429,nop,nop,sack 1 {2477460020:2477460699}], length 0
03:42:29.292107 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47113819 ecr 140380062], length 1368
03:42:32.192137 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47114544 ecr 140380062], length 1368
03:42:38.000125 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47115996 ecr 140380062], length 1368
03:42:40.064116 IP venus.markhobley.yi.org.52198 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47116512 ecr 140379776], length 1368
03:42:49.600135 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47118896 ecr 140380062], length 1368
03:42:50.439130 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.51218: Flags [R], seq 4178125634, win 0, length 0
03:42:53.504132 IP venus.markhobley.yi.org.52197 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47119872 ecr 140371591], length 1368
03:42:57.843979 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [FP.], seq 4849:5371, ack 324, win 457, options [nop,nop,TS val 47120956 ecr 140380062], length 522
03:42:59.663041 IP venus.markhobley.yi.org.52200 > news.eternal-september.org.nntp: Flags [S], seq 2233139354, win 14600, options [mss 1460,sackOK,TS val 47121411 ecr 0,nop,wscale 5], length 0
03:42:59.663736 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52199: Flags [.], ack 66, win 46, options [nop,nop,TS val 140387975 ecr 47113429,nop,nop,sack 2 {2477463435:2477463958}{2477460020:2477460699}], length 0
03:42:59.770427 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52200: Flags [S.], seq 1693600159, ack 2233139355, win 5792, options [mss 1380,sackOK,TS val 140388003 ecr 47121411,nop,wscale 7], length 0
03:42:59.770510 IP venus.markhobley.yi.org.52200 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47121438 ecr 140388003], length 0
03:42:59.880540 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52200: Flags [P.], seq 1:48, ack 1, win 46, options [nop,nop,TS val 140388031 ecr 47121438], length 47
03:42:59.880612 IP venus.markhobley.yi.org.52200 > news.eternal-september.org.nntp: Flags [.], ack 48, win 457, options [nop,nop,TS val 47121466 ecr 140388031], length 0
03:42:59.880857 IP venus.markhobley.yi.org.52200 > news.eternal-september.org.nntp: Flags [F.], seq 1, ack 48, win 457, options [nop,nop,TS val 47121466 ecr 140388031], length 0
03:42:59.881260 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52200: Flags [F.], seq 48, ack 1, win 46, options [nop,nop,TS val 140388031 ecr 47121438], length 0
03:42:59.881282 IP venus.markhobley.yi.org.52200 > news.eternal-september.org.nntp: Flags [.], ack 49, win 457, options [nop,nop,TS val 47121466 ecr 140388031], length 0
03:42:59.990509 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52200: Flags [.], ack 2, win 46, options [nop,nop,TS val 140388058 ecr 47121466], length 0
03:43:04.320740 IP venus.markhobley.yi.org.52201 > news.eternal-september.org.nntp: Flags [S], seq 2304145392, win 14600, options [mss 1460,sackOK,TS val 47122576 ecr 0,nop,wscale 5], length 0
03:43:04.500693 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52201: Flags [S.], seq 1766167236, ack 2304145393, win 5792, options [mss 1380,sackOK,TS val 140389170 ecr 47122576,nop,wscale 7], length 0
03:43:04.500777 IP venus.markhobley.yi.org.52201 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47122621 ecr 140389170], length 0
03:43:04.680475 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52201: Flags [P.], seq 1:48, ack 1, win 46, options [nop,nop,TS val 140389215 ecr 47122621], length 47
03:43:04.680550 IP venus.markhobley.yi.org.52201 > news.eternal-september.org.nntp: Flags [.], ack 48, win 457, options [nop,nop,TS val 47122666 ecr 140389215], length 0
03:43:04.680953 IP venus.markhobley.yi.org.52201 > news.eternal-september.org.nntp: Flags [F.], seq 1, ack 48, win 457, options [nop,nop,TS val 47122666 ecr 140389215], length 0
03:43:04.700317 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52201: Flags [F.], seq 48, ack 1, win 46, options [nop,nop,TS val 140389215 ecr 47122621], length 0
03:43:04.700381 IP venus.markhobley.yi.org.52201 > news.eternal-september.org.nntp: Flags [.], ack 49, win 457, options [nop,nop,TS val 47122671 ecr 140389215], length 0
03:43:04.860278 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52201: Flags [.], ack 2, win 46, options [nop,nop,TS val 140389261 ecr 47122666], length 0
03:43:11.182591 IP venus.markhobley.yi.org.52202 > news.eternal-september.org.nntp: Flags [S], seq 2424765077, win 14600, options [mss 1460,sackOK,TS val 47124291 ecr 0,nop,wscale 5], length 0
03:43:11.752242 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52202: Flags [S.], seq 1875583976, ack 2424765078, win 5792, options [mss 1380,sackOK,TS val 140390973 ecr 47124291,nop,wscale 7], length 0
03:43:11.752329 IP venus.markhobley.yi.org.52202 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47124434 ecr 140390973], length 0
03:43:12.302119 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52202: Flags [P.], seq 1:48, ack 1, win 46, options [nop,nop,TS val 140391105 ecr 47124434], length 47
03:43:12.302192 IP venus.markhobley.yi.org.52202 > news.eternal-september.org.nntp: Flags [.], ack 48, win 457, options [nop,nop,TS val 47124571 ecr 140391105], length 0
03:43:12.302435 IP venus.markhobley.yi.org.52202 > news.eternal-september.org.nntp: Flags [F.], seq 1, ack 48, win 457, options [nop,nop,TS val 47124571 ecr 140391105], length 0
03:43:12.342004 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52202: Flags [F.], seq 48, ack 1, win 46, options [nop,nop,TS val 140391105 ecr 47124434], length 0
03:43:12.342072 IP venus.markhobley.yi.org.52202 > news.eternal-september.org.nntp: Flags [.], ack 49, win 457, options [nop,nop,TS val 47124581 ecr 140391105], length 0
03:43:12.832110 IP venus.markhobley.yi.org.52199 > news.eternal-september.org.nntp: Flags [.], seq 66:1434, ack 324, win 457, options [nop,nop,TS val 47124704 ecr 140387975], length 1368
03:43:13.072128 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52202: Flags [.], ack 2, win 46, options [nop,nop,TS val 140391306 ecr 47124571], length 0
03:43:14.812402 IP venus.markhobley.yi.org.52203 > news.eternal-september.org.nntp: Flags [S], seq 2475930012, win 14600, options [mss 1460,sackOK,TS val 47125199 ecr 0,nop,wscale 5], length 0
03:43:15.343213 IP news.eternal-september.org.nntp > venus.markhobley.yi.org.52203: Flags [S.], seq 1926348286, ack 2475930013, win 5792, options [mss 1380,sackOK,TS val 140391873 ecr 47125199,nop,wscale 7], length 0
03:43:15.343299 IP venus.markhobley.yi.org.52203 > news.eternal-september.org.nntp: Flags [.], ack 1, win 457, options [nop,nop,TS val 47125331 ecr 140391873], length 0

I am no expert on breaking the above report down, so I need to read back
through some archives, so I can get my head around the above report. 
However, examining the binary version of the above file for strings, I can
see that fragments of the usenet data are being retransmitted.

What has happened here?

If I disable PMTUD with following command, then usenet works fine (Hence my
theory that the problem is related to packet maximum segment size that
my ISP can convey downstream).

Thanks in advance to anyone who can shine any light on this.

Mark.

-- 
Mark Hobley
Linux User: #370818  http://markhobley.yi.org/

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Thread

Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-21 14:58 +0000
  Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2011-05-21 15:16 -0400
    Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-21 22:02 +0000
      Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2011-05-22 19:59 +0300
        Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 17:09 +0000
  Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-21 20:20 +0000
    Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Richard Kettlewell <rjk@greenend.org.uk> - 2011-05-21 22:47 +0100
    Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-21 22:28 +0000
      Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 01:15 +0000
        Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-22 06:01 +0000
          Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 07:28 +0000
            Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Andy Furniss <spam@andyfurniss.entadsl.com> - 2011-05-22 11:40 +0100
              Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 12:25 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Andy Furniss <spam@andyfurniss.entadsl.com> - 2011-05-22 20:40 +0100
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Andy Furniss <spam@andyfurniss.entadsl.com> - 2011-05-22 20:56 +0100
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 22:57 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 23:12 +0000
            Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-22 11:31 +0000
              Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 11:50 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-22 12:52 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 13:27 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-22 19:19 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-22 22:12 +0000
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-25 15:55 +0000
                ip route - Wrong Maximum Segment Size being advertised Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-25 17:27 +0000
                Re: Linux 2.6.39.1 - Wrong Maximum Segment Size in both directions Mark Hobley <markhobley@yahoo.donottypethisbit.co> - 2011-05-29 00:34 +0000
                Re: Linux 2.6.39.1 - Wrong Maximum Segment Size in both directions Andy Furniss <spam@andyfurniss.entadsl.com> - 2011-05-29 11:11 +0100
                Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Martijn Lievaart <m@rtij.nl.invlalid> - 2011-05-23 08:13 +0200
    Re: Linux 2.6.39-rc7 - Wrong Maximum Segment Size being advertised Barry Margolin <barmar@alum.mit.edu> - 2011-05-22 00:44 -0400

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