SpeedConnect Internet Accelerator
software to boost your connection
software to boost your connection
RWIN (TCP Receive Window)
The TCP Receive Window size is the amount of receive data (in bytes)
that can be buffered at one time on a connection. The sending host can send only that amount of data before waiting
for an acknowledgment and window update from the receiving host. Matching the receive window to even increments
of the MSS increases the percentage of full-sized TCP segments utilized during bulk data transmission. MSS is the
MaxMTU - 40 bytes for TCP and IP headers.
The RWIN default is 8192 bytes rounded up to the nearest MSS increment for the connection. If that isn't at least
4 times the MSS, then it's adjusted to 4 * MSS, with a maximum size of 64K. With the Windows 95 default MaxMTU
of 1500, the default RWIN is rounded up to 8760 (1460 * 6). You can greatly improve performance by setting this
to a lower value such as 4 times your MSS (MTU-40). The idea is to bring it to a value below 8192. Many people
have better success with 6, 8 or even 10* MSS. In some cases, however, manually setting RWIN may decrease performance
because it takes the control away from windows, and if the MTU is negotiated to a different value, then the size
of the RWIN is no longer an whole integer multiple. For this to be effective you must make sure your MTU is set
where it will not be negotiated to a lower value.
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