Time-Out Mechanism in the Host-Host Protocol

This can happen if the NCP is not running at all but its host is taking in messages (e.g. UCLA’s host will receive messages even if the NCP is not running), or if the NCP is running very slowly. The same problem exists on sending out a CLS control command and a matching CLS is never returned. The trouble is that resources are tied up, e.g. sockets, links and table space in the NCP; and one would like to release these resources. In our implementation, when a user does a CLOSE, we can’t release the sockets until the matching CLS is returned. This protects us from getting confused if a seconds request is made for the same pair of sockets. This problem can be solved by including a time-out mechanism in the Host-Host protocol. This operates as follows: