For this specification the MSL is taken to be 2 minutes. This is an engineering choice, and may be changed if experience indicates it is desirable to do so.
The specification calls for this value to be used for the "time-wait" interval, the minimum time a system must keep the socket in the TIME_WAIT state before designating the socket closed, thus preventing the socket from being re-used before that interval.
Values in various operating systems
The command that can be used on Solaris systems (prior to v11) to determine the time-wait interval is:
ndd -get /dev/tcp tcp_time_wait_interval
60000 (60 seconds) is a common value.
sysctl -d net.inet.tcp.msl sysctl net.inet.tcp.msl
which gets the result:
net.inet.tcp.msl: Maximum segment lifetime net.inet.tcp.msl: 30000
In Linux, the time-wait interval is defined by the TCP_TIMEWAIT_LEN, hard-coded as 60 seconds. Linux implements several possible optimizations to shorten the TIME_WAIT state through recycling, down to a minimum of 3.5s in recent kernels.
- "RFC 793". Transmission Control Protocol. Retrieved December 5, 2006.
- "Tuning FreeBSD to serve 100-200 thousands of connections".
- "Linux Kernel socket implementation".
- "Linux Kernel headers for TCP".