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Hi, I have two Fedora FC7 machines connected to my DSL line. Things were working fine until the ISP disconnected the service. The connection is now back, but with different ...
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  1. #1
    Just Joined!
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    Oct 2006
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    Network stalls after IP change


    Hi,

    I have two Fedora FC7 machines connected to my DSL line. Things were working fine until the ISP disconnected the service. The connection is now back, but with different static IP addresses.

    Previously I had both servers configured via static IP, however I changed them to DHCP so that they would pick up their new public (and actually static) addresses.

    Things are okay in that I can SSH into both machines, however any attempt to download a large file results in the connection stalling. It starts fast and then rapidly (within a couple of seconds) goes down to zero. It does download some of the file, so it's really stalling and not just reporting bad information. I should say I've tried this with many files from many servers.

    I've no idea what I've done on these two machines to screw them both up in the same way. It's not the cable or router as if I pull it out of the linux machine and plug it into a Windows machine then I get the full 8MB service with no stalls.

    Does anyone have any suggestions as to what I could look at to debug this?

    Thanks

  2. #2
    Just Joined!
    Join Date
    Oct 2006
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    11
    If it helps, to test I've tried the following download:

    Code:
    wget http://cachefly.cachefly.net/10mb.test
    And tcpdump shows me the following

    Code:
    13:41:22.223850 IP (tos 0x0, ttl 45, id 25792, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 125838:127298(1460) ack 138 win 6432
    13:41:22.223874 IP (tos 0x0, ttl 64, id 46982, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x2bb9 (correct), 138:138(0) ack 127298 win 65535
    13:41:22.235839 IP (tos 0x0, ttl 45, id 25794, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 128758:130218(1460) ack 138 win 6432
    13:41:22.235865 IP (tos 0x0, ttl 64, id 46983, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x2bb9 (correct), 138:138(0) ack 127298 win 65535
    13:41:22.257302 IP (tos 0x0, ttl 45, id 25795, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 130218:131678(1460) ack 138 win 6432
    13:41:22.257326 IP (tos 0x0, ttl 64, id 46984, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x2bb9 (correct), 138:138(0) ack 127298 win 65535
    13:41:22.269143 IP (tos 0x0, ttl 45, id 25796, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 131678:133138(1460) ack 138 win 6432
    13:41:22.269163 IP (tos 0x0, ttl 64, id 46985, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x2bb9 (correct), 138:138(0) ack 127298 win 65535
    13:41:22.281282 IP (tos 0x0, ttl 45, id 25797, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 133138:134598(1460) ack 138 win 6432
    13:41:22.281302 IP (tos 0x0, ttl 64, id 46986, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x2bb9 (correct), 138:138(0) ack 127298 win 65535
    13:41:22.302673 IP (tos 0x0, ttl 45, id 25798, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 134598:136058(1460) ack 138 win 6432
    13:41:22.302693 IP (tos 0x0, ttl 64, id 46987, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x2bb9 (correct), 138:138(0) ack 127298 win 65535
    13:41:22.312533 IP (tos 0x0, ttl 45, id 25799, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: P 127298:128758(1460) ack 138 win 6432
    13:41:22.312565 IP (tos 0x0, ttl 64, id 46988, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x0981 (correct), 138:138(0) ack 136058 win 65535
    13:41:22.346400 IP (tos 0x0, ttl 45, id 25800, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 136058:137518(1460) ack 138 win 6432
    13:41:22.346430 IP (tos 0x0, ttl 64, id 46989, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0x03cd (correct), 138:138(0) ack 137518 win 65535
    13:41:22.363844 IP (tos 0x0, ttl 45, id 25801, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 137518:138978(1460) ack 138 win 6432
    13:41:22.363867 IP (tos 0x0, ttl 64, id 46990, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0xfe18 (correct), 138:138(0) ack 138978 win 65535
    13:41:22.393302 IP (tos 0x0, ttl 45, id 25802, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 138978:140438(1460) ack 138 win 6432
    13:41:22.393324 IP (tos 0x0, ttl 64, id 46991, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0xf864 (correct), 138:138(0) ack 140438 win 65535
    13:41:22.409068 IP (tos 0x0, ttl 45, id 25803, offset 0, flags [DF], proto TCP (6), length 1500) vip1.cdn.cachefly.net.http > dannii.51467: . 140438:141898(1460) ack 138 win 6432
    13:41:22.409102 IP (tos 0x0, ttl 64, id 46992, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: ., cksum 0xf2b0 (correct), 138:138(0) ack 141898 win 65535
    Then it stalls untils I ctrl-c the download task, then spits out the following:


    Code:
    13:41:48.479056 IP (tos 0x0, ttl 64, id 46993, offset 0, flags [DF], proto TCP (6), length 40) dannii.51467 > vip1.cdn.cachefly.net.http: F, cksum 0xf2af (correct), 138:138(0) ack 141898 win 65535
    13:41:48.513289 IP (tos 0x0, ttl 52, id 0, offset 0, flags [DF], proto TCP (6), length 40) vip1.cdn.cachefly.net.http > dannii.51467: R, cksum 0x5e9f (correct), 4042494123:4042494123(0) win 0

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