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Silly window syndrome is a problem in computer networking caused by poorly implemented TCP flow control. A serious problem can arise in the sliding window operation when the sending application program creates data slowly, the receiving application program consumes data slowly, or both. If a server with this problem is unable to process all incoming data, it requests that its clients reduce the amount of data they send at a time (the window setting on a TCP packet). If the server continues to be unable to process all incoming data, the window becomes smaller and smaller, sometimes to the point that the data transmitted is smaller than the packet header, making data transmission extremely inefficient. The name of this problem is due to the window size shrinking to a "silly" value. Since there is a certain amount of overhead associated with processing each packet, the increased number of packets means increased overhead to process a decreasing amount of data. The end result is thrashing. ==Solution== When there is no synchronization between the sender and receiver regarding capacity of the flow of data or the size of the packet, the window syndrome problem is created. When the silly window syndrome is created by the sender, Nagle's algorithm is used. Nagle's solution requires that the sender send the first segment even if it is a small one, then that it wait until an ACK is received or a maximum sized segment (MSS) is accumulated. When the silly window syndrome is created by the receiver, David D Clark's solution is used. Clark's solution closes the window until another segment of maximum segment size (MSS) can be received or the buffer is half empty. There are 3 causes of SWS: # When the server announces Empty space as 0 # When client is able to generate only 1 byte at a time # When server is able to consume only 1 byte at a time During SWS, efficiency of communication is almost 0, so SWS duration should be short as possible. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Silly window syndrome」の詳細全文を読む スポンサード リンク
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