Browse Prior Art Database

Synchronization of ISDN Global Call Clearing

IP.com Disclosure Number: IPCOM000107194D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Jongekryg, BE: AUTHOR [+4]

Abstract

In some data communication environments, the order of CONFIRMATIONs and INDICATIONs (primitives sent from a lower layer in the protocol stack to a higher layer) may change due to the nature of the transport mechanism between the layers. If this occurs in a device attached to an ISDN interface that is globally clearing previous calls (involves CONFIRMATION) at about the same time as new calls arrive (involves INDICATIONs), the state of the new calls may be ambiguous for higher layers in the device. A method for eliminating this ambiguity is disclosed.

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Synchronization of ISDN Global Call Clearing

       In some data communication environments, the order of
CONFIRMATIONs and INDICATIONs (primitives sent from a lower layer in
the protocol stack to a higher layer) may change due to the nature of
the transport mechanism between the layers.  If this occurs in a
device attached to an ISDN interface that is globally clearing
previous calls (involves CONFIRMATION) at about the same time as new
calls arrive (involves INDICATIONs), the state of the new calls may
be ambiguous for higher layers in the device.  A method for
eliminating this ambiguity is disclosed.

      When a device receives new ISDN calls at about the same time
that the device is clearing previous ISDN calls, call state
synchronization may be maintained between protocol stack layers by
using the following "scoping" technique:
      PRIMITIVE FIELDS AND INTERNAL VARIABLES:
      -  A SCOPE field is included in the following primitives that
flow from Layer N to Layer N+1 in the user device:
           -  REGISTER indication, which corresponds to an incoming
call (Q.932 REGISTER message).
           NOTE:  Incoming CCITT Q.932 REGISTER messages are used as
an example.  Incoming CCITT Q.931 SETUP messages may be handled using
a similar mechanism.  In this article, "call" is used as a generic
term that includes (1) ISDN calls and (2) associations with calls for
performing certain supplementary services, such as call forwarding.
           -  RESTART confirmation, which corresponds to completion
of global call clearing (CCITT Q.931 RESTART...