Microsoft KB Archive/290206

= PRB: UDP Datagrams Being Dropped Under Load =

Article ID: 290206

Article Last Modified on 4/15/2004

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APPLIES TO


 * Microsoft Windows CE 3.0 for the Handheld PC
 * Microsoft Windows CE 2.12 for the Handheld PC
 * Microsoft Windows CE 2.11 for the Handheld PC
 * Microsoft Windows CE 2.0 for the Handheld PC

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This article was previously published under Q290206



SYMPTOMS
Windows CE internally maintains a per socket queue of User Datagram Protocol (UDP) datagrams that haven't yet been processed by applications. Once this queue fills up, packets are discarded (beginning with the oldest ones first). The result is that applications that send a large number of UDP datagrams quickly can experience large amounts of packet loss.



MORE INFORMATION
The default internal UDP buffer queue size is 2. If a platform must support applications that potentially deliver more than 2 datagrams in a very short time (the time needed to process a packet, which is highly dependant on network and platform characteristics), the default limit can be raised. The value necessary would depend on the specific application, but a practical range might be 2 to 10 hex. Here is an example of the altered registry setting:

[HKEY_LOCAL_MACHINE\Comm\Afd]

DgramBuffer=dword:8

The device must be reset for this parameter to take effect.

Keywords: kbprb KB290206

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