[Robustness] Re: Call Clearing related

Paul E. Jones paul.jones at ties.itu.int
Tue Nov 2 23:27:49 EST 1999


Chris,

> A technical question on the second paragraph of your mail: how do
endpoints
> KNOW that they're connected directly rather than through a gatekeeper, in
order
> to decide whether they can (under the current system) drop the
call-signalling
> channel?

First of all... sorry for the delayed response.  I am a bit behind :-)

I, too, noticed this funny little sentence in the standard.  In theory, the
GK would signal that the call is being routed, but that may not necessarily
be the case.

I believe it is clear that we must address this issue.  I would like to
strike the text as I proposed.  I also believe it might be wise to add a
paragraph to V4 noting that V3 and older terminals may close the call
signaling channel, along the lines of your e-mail.

Another issue we have at hand is that of "what is a call signaling channel?"
There used to be a one to one mapping between TCP connections and call
signaling channels.  This is not the case any longer-- one may have multiple
calls over the same call signaling channel and one may not even use TCP.

Making this distinction will be important for the robustness work being
started, as the "logical" connection (the call signaling channel) and the
"physical" connection (the TCP or UDP connection) must be referred to
independently.  (I'm quite open to new terms for here...).  It is important
to recognize whether an endpoint has closed the call signaling channel (as
we understand it today) or if the physical connection has failed.  Since we
do not signal that we are going to close the call signaling channel today--
we just close the socket-- it makes this problem more difficult.

Paul



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