SGH_WIKI

This is an old revision of the document!

Formula for TCP Performance/Latency/Window Size

Formula:

TCP throughput = TCP-Window-Size-in-bits / Latency-in-seconds = Bits-per-second-throughput

Optimal TCP window size in bytes = Bandwidth-in-bits-per-second * Round-trip-latency-in-seconds = TCP window size in bits / 8

Maximum Latency for a desired throughput =TCP-window-size-bits / Desired-throughput-in-bits-per-second = Maximum RTT Latency

For example: Windows size is 64K bytes, and its round trip latency is 0.03 seconds, then:

                     1 Gbps Link Rate
    Server  <--------------------------------->    Client 
               Round Rrip Latency is 0.03

TCP throughput of 1 flow = 64K bytes/0.03 seconds = 65536 Bytes/0.03 = 65536 * 8 bits/0.03 = 17.4 Mbps