TCP Window update issue in Windows Embedded Standard 7 RRS feed

  • Question

  • Hi,

    OS: Windows Embedded Standard 7

    Application: FTP Server which will be able to send and receive files over FTPS.

    When receiving large files(about 35 MB) from FTP Client, sometimes TCP Zero Window occurred on FTP Server PC after which TCP retransmission occurred. 

    But sometimes, FTP Server PC is able to recover from TCP Zero Window quickly by sending TCP Window update.

    In the TCP Communication between client and server PC, as when data is received from the FTP Client, TCP Window size is decreased at FTP Server side.

    But, why TCP Window update is not sent from FTP Server side?

    The window scaling at FTP Server side is mentioned below which is obtained from SYN packet.

    Window scale: 8 (multiply by 256)

    Kind: Window Scale (3)

    Even though ACK is sent for each and every packet received from the FTP Client with out any delay, why TCP Window update does not occur?

    Apart from FTP Server unable to read the data as faster as the data sent, is there any other reason from TCP ZERO Window?

    Is there any work around or PC setting which will automatically increase the TCP Window size immediately when TCP ZERO Window occurs?

    What need to be done by application which will lead to TCP Window update from PC?

    Thanks in advance.

    Tuesday, July 14, 2015 12:35 PM

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