The TIME_WAIT state is a state that all the TCP connections enter into when the connection has been closed. The length of time for this state is 240 seconds, which is to allow for any duplicate segments still in the network from the previous connection to expire. The introduction of the new CC option in T/TCP allows for the truncation of the TIME_WAIT state. The CC option provides protection against old duplicates being delivered to the wrong incarnation for a given connection.
There are time constraints on this though. Because the CC value from the host is monotonically increasing, there is a possibility that the numbers may wrap around from the client host. A CC value that is the same as some duplicate segments from the previous incarnation may be encountered. As a rule, the truncation can only be performed whenever the duration of the connection is less than the maximum segment lifetime (MSL). The recommended value for the MSL is 120 seconds. As with the original TCP, the host that sends the first FIN is required to remain in the TIME_WAIT state for twice MSL once the connection is completely closed at both ends. This implies that the TIME_WAIT state with the original TCP is 240 seconds, even though some implementations of TCP have the TIME_WAIT set to 60 seconds. Stevens ([STEVENS] page 54) shows how the TIME_WAIT state for T/TCP may be shortened to 12 seconds.