better utilize the bandwidth of TCP connections in VISTA

[MikeyHunt]

To better utilize the bandwidth of TCP connections in Vista, the Next Generation TCP/IP stack includes Compound TCP (CTCP).

CTCP more aggressively increases the send window for connections with large receive window sizes and BDPs.

CTCP attempts to maximize throughput on these types of connections by monitoring delay variations and losses.

In addition, CTCP ensures that its behavior does not negatively impact other TCP connections.

In testing performed internally at Microsoft, large file backup times were reduced by almost half for a 1Gbps connection with a 50ms RTT.

Connections with a larger BDP can have even better performance. CTCP and Receive Window Auto-Tuning work together for increased link utilization and can result in substantial performance gains for connections with large BDPs.

CTCP is enabled by default in computers running Windows Server "Longhorn" and disabled by default in computers running Windows Vista.

You can enable CTCP in Vista with the > command prompt> netsh interface tcp set global congestionprovider=ctcp

You can disable CTCP with the > command prompt> netsh interface tcp set global congestionprovider=none