Q: I have been looking through Volume 1 & 2 on the topics of TCP timeouts. I have been looking in the section on "Timeout And Retransmission" where you talk about round trip times. My question to you would be what would make a tcp connection timeout? Is there a certain number of retries that need to happen before a timeout?
A: TCP does not define a maximum number of retransmissions before giving up. However, it does define a maximum segment lifetime, and assumes that no response within two maximum segment lifetimes indicates a hopeless situation. Thus, if one attempts to communicte with a machine that is down, TCP will give up after retransmitting for about 5 minutes Copied from a FAQ. TCP will not let you know that the socket is down until you try to send or recieve on the socket. At that time a socket error will occur. And unless he has odd gear, the nagle algorithm will not hold a packet back if there's no packets still being transmitted (ack pairs haven't been received). I've had one radio which repackaged things funny, but the data still got through, it just took some time. -- http://mail.python.org/mailman/listinfo/python-list