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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical TCP congestion
Can someone explain how a TCP conversation could degenerate into congestion avoi dance on a long fat pipe if there is no packet/segment loss or out of order segm ents? Here is the situation: WAN = 9 Mbps ATM connection between NY and LA (70 ms delay) LAN = Gig Ethernet Receiver: LA server = Win2k3 Sender: NY server = Linux 2.4 Data transmission typical = bursty but never more that 50% of CIR Segment sizes = 64k to 1460k but mostly less than 100k Typical Problem Scenario: Data transmission is humming along consistently at 2 M bps, all of a sudden transmission rates drop to nothing then pickup again after 15-20 seconds. Prior to the drop off (based on packet capture) there is usually a DUP ACK/SACK coming from the receiver followed by the Retransmits and congesti on avoidence. What is strange is there is nothing prior to the drop off that wou ld be an impetus for congestion (no high BW utilization or packet loss). Also is there any known TCP issues between linux 2.4 kernel and windows 2003 SP1 ? Mainly are there issues regarding the handling of SACK, DUP ACK's and Fast Ret ransmits. Of course we all know that this is not a application issue since developers make flawless socket code, but if it is network issue how is caused? Philip ________________________________________________________________________________ ____ Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more. http://mobile.yahoo.com/go?refer=1GNXIC
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