Effect of 2MSL wait
Can’t kill server & restart immediately to use the same well known port (1-4 min!)
Reason: TCP cannot reallocate the socket pair (i.e. the connection) till 2MSL.
If you kill client and restart, it will get a different port
2MSL wait protects against delayed segments from the previous “incarnation” of the connection.
If server crashes and reboots within 2 MSL wait, it is still safe because RFC 793 prevents having connections for 1 MSL after reboot.