Windows Vista and Windows Server 2008 have a new TCP/IP stack which includes a new set of performance enhancements to increase throughput in networking environments. One enhancement feature is CTCP – Compound TCP CTCP, which increases the send window for connections with large receive window sizes and large bandwidth-delay.
The Cable Guy newsletter at Microsoft’s Technet site has an article detailing this which was actually written back in 2005, although has since be updated. The article is available at this link:
http://www.microsoft.com/technet/community/columns/cableguy/cg1105.mspx
By default Windows Server 2008 has CTCP enabled, however Vista does not. So far with my testing, having it switched on in Vista has no side effects, and has made transferring data quicker, so turn it on!!
Use NETSH to turn it on, you can easily turn it off with another NETSH command see below:
Enable CTCP with:
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netsh interface tcp set global congestionprovider=ctcp
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Disable it with:
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netsh interface tcp set global congestionprovider=none
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