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Short Hold Mode in ISDN

IP.com Disclosure Number: IPCOM000099929D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 95K

Publishing Venue

IBM

Related People

Villedieu, C: AUTHOR

Abstract

In a switched environment, it may be efficient for data communications to make a distinction between a session and a call. If the session and the call are established and released at the same time, the overall performance could be very inefficient as the number of parameters to be established for a data communication session is quite significant. In particular, if the call duration corresponding to the data transfer over the session is short, most of the time will be spent to re-establish the session parameters. The physical path itself should be released when the session is quiescent, but this may not mean the end of the session. So, it is important to hold the session while the physical path is released and further re-established when there is a new set of data to exchange.

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Short Hold Mode in ISDN

       In a switched environment, it may be efficient for data
communications to make a distinction between a session and a call. If
the session and the call are established and released at the same
time, the overall performance could be very inefficient as the number
of parameters to be established for a data communication session is
quite significant.  In particular, if the call duration corresponding
to the data transfer over the session is short, most of the time will
be spent to re-establish the session parameters. The physical path
itself should be released when the session is quiescent, but this may
not mean the end of the session. So, it is important to hold the
session while the physical path is released and further
re-established when there is a new set of data to exchange.

      Most implementations today offer this decoupling capability.
However, some call parameters such as the called party number need to
be sent at each re-establishment of the physical path over a switched
network. It prohibits the use of networks presenting a slow response
time for call set-up. The possibility to hold the physical path for a
short period of time is only possible in a fast switching network
environment (i.e., X.21). The emergence of new switching technologies
such as ISDN offers an implementation alternative.

      In an ISDN network, the signaling channel is extremely powerful
(over 40 messages already defined with room for detailed information
element in each message); so, it could be possible to disconnect the
physical path while holding the network parameters required for re-
establishing the call later. There are possible two main
implementations:
1.   "a la X21" where the call is fully released and further fully
re-established. In this...