> The problem I'm having is a huge increase in 'in session' disconnections
> after my upgrade to 3.8.2. I rebooted (power cycled) the PM3 the other
> night and some of the problems went away. Some of it was modem types;
> Global Village modems still disconnect randomly for sure.
My money's on the line signalling (PRI/CT1) code being the culprit here.
Let's look (selectively) at the evidence:
1) Some people have problems, others do not
2) (PRI/CT1) line termination varies from ISP to ISP depending on their
telco
3) While there are some modems that work across the board, there are
modems with exactly the same make/model/firmware that connect fine with
some people and not others
4) ComOS 3.8 has well-known and observable line problems in *certain*
situations
Now, let's assume that this is a line synchronisation problem with your
PRI/CT1 frames gradually slipping further and further out of
synchronisation as time passes. Synchronisation frames will be sent out
every n frames which will resynchronise the pm3 and the terminating
switch. As long as n is small enough, the synchronisation frames will
come fast enough to prevent the slippage being noticed.
If n is the appropriate size so that you lose one or two frames every few
seconds then you will lose data and the upper layers of the protocol stack
will pick it and error-correct (by re-transmission or some other means).
Some modems will less tolerant to lose of data than others and will
interpret this to mean that the remote modem has gone away and drop the
line (reporting lost carrier). If n is really big, then your problems
will be more severe and synchronisation may be lost completely.
Of course, this is just the guessing of a computer scientist and will
probably be corrected in due course by a knowledgeable telecoms engineer.
:-)
-- Richard Morrell richard@ednet.co.uk System Administrator - edNET: Internet Access for Edinburgh - www.ednet.co.uk
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