CDC-DDN@DDN3.ARPA (09/09/87)
We are having a problem using UNIX 4.3 sendmail. It will send messages to our CYBER quickly (1 sec) for a while, and then will gradually take longer and longer to send a message until finally it takes so long (7 minutes) to send the message that some UNIX timer kicks in and aborts the connection. When this happens, all subsequent messages time out in this manner, and we cannot send messages to the CYBER until we re-boot the VAX. We have looked at this with both an Ethernet analyzer and using the debug facility within sendmail. In the slow transactions, there is a delay of several minutes between the time that UNIX TCP receives the 354 reply to the DATA command, and the time that UNIX TCP sends the message text. The delay is always at this one point, and there is no other difference between slow and fast transactions. Even in sessions that time out, the sendmail debug output indicates that sendmail believes it has sent the message text, but it never appears on the Ethernet. There are no retransmission packets or ICMP messages to indicate some lower-level problem. Does anyone know what might be causing this problem? Any pointers will be appreciated. Mike Sanders CDC-DDN@DDN3