Ref: 05270025
Title: Discussion of Message "transmit fail" in 3+Route
Date: 7/22/88

Copyright 3Com Corporation, 1991.  All rights reserved.

The "transmit fail" message in the Status.log is a result of
3+Route sending several retransmitted packets with no
acknowledgement.  Route decides the connection is broken and
hangs up.  We think that something is causing the data channel to
be broken, 3+Route logs a "transmit fail", and then 3+Route
issues the hang up to the modem.

There are four modem control signals that could possibly affect
the server:

CD (Carrier Detect) -- A momentary loss of this will cause an
interrupt to the driver, suspension of driver activity, and an
eventual "transmit fail" in the Router.

CTS (Clear to Send) -- A momentary loss of this will cause a
transparent hang.  When it comes back on data transmission will
resume with the 3Server being none the wiser.

RI (Ring Indicator) -- This coming on during data trasmission
will probably be ignored as it is illogical to the state machine
that is controlling the link.

DSR (Data Set Ready) -- This is totally ignored by the 3Server.
