This counts how many times the T2-shutdown timer expired for this association during the graceful shutdown handshake, meaning a SHUTDOWN or SHUTDOWN-ACK chunk had to be retransmitted because the peer didn't acknowledge it promptly. Associations showing nonzero T2 expirations took longer than expected to tear down cleanly, which - while not usually service-affecting since the association is already closing - can indicate the peer was under load or the path was degraded right at the end of the session. A pattern of frequent T2 expirations specifically correlating with certain peers, rather than being spread evenly, would point at that peer's shutdown handling rather than a general network issue.