3.5.6.1 Session Inactivity Timer Expiry
When this timer fires, each entry in the Session Table MUST be checked for inactivity as follows. If the session is not in the temporary state and its type of service identifier is topology discovery, and the topology discovery state engine is in the Command state, the session MUST be considered inactive if 60 seconds or more have elapsed since the active time. Otherwise, the session MUST be considered inactive if 30 seconds or more have elapsed since the active time.
If a session is considered inactive, it MUST be removed, and the enumeration state engine's state MUST be updated as specified in section 3.5.5.4.
This timer MUST be reset so it continues firing until the enumeration state engine transitions back to the Quiescent state.