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How to find and modify the tcp buffer window size on win 2k8


we are facing very slow downloads of an 80 MB file when its being downloaded from Phoenix to San Jose

Our network team is saying increase the tcp window size of the hosting server (the server is a VM of win 2k8)

How can I do that ? Please explain this to me in layman's term and not MSFT KB articles

1 Solution
Windows 2008 does TCP receive window size auto-tuning and from what I understand setting the registry like you could in Windows 2003 won't matter, since it dynamically tunes to the best receive window size.

You can look here for details: http://technet.microsoft.com/en-us/library/bb726965.aspx

Receive Window Auto Tuning

The TCP receive window size is the amount of data that a TCP receiver allows a TCP sender to send before having to wait for an acknowledgement. To correctly determine the value of the maximum receive window size for a connection based on the current conditions of the network, the Next Generation TCP/IP stack supports Receive Window Auto-Tuning. Receive Window Auto-Tuning continually determines the optimal receive window size on a per-connection basis by measuring the bandwidth-delay product (the bandwidth multiplied by the latency of the connection) and the application retrieve rate, and automatically adjusts the maximum receive window size on an ongoing basis.

With better throughput between TCP peers, the utilization of network bandwidth increases during data transfer. If all the applications are optimized to receive TCP data, then the overall utilization of the network can increase substantially, making the use of Quality of Service (QoS) more important for networks that are operating at or near capacity. For more information, see "Quality of Service" in this article.

That said...go back to your network team and tell them you cannot per that Technet article.

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