Browse Prior Art Database

Transparent Message Routing between an SS 7 Network and X.25 Network

IP.com Disclosure Number: IPCOM000109409D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 3 page(s) / 130K

Publishing Venue

IBM

Related People

Schweikert, DE: AUTHOR [+2]

Abstract

The telecommunications industry has adopted Signalling System 7 (SS 7) as the preferred medium for performing out of band signalling. This protocol is particularly useful for transmitting queries for additional information to a central data base, and for that central data base to return the appropriate query responses. In the past, these data base functions have often been handled using less efficient packet switched networks based on X.25. Now, the telecommunications industry is in transition from X.25 to SS 7; one of the major issues is how to smoothly connect the new SS 7-based public switched networks with existing X.25 private networks (and their associated applications) during this transition.

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Transparent Message Routing between an SS 7 Network and X.25 Network

       The telecommunications industry has adopted Signalling
System 7 (SS 7) as the preferred medium for performing out of band
signalling.  This protocol is particularly useful for transmitting
queries for additional information to a central data base, and for
that central data base to return the appropriate query responses.  In
the past, these data base functions have often been handled using
less efficient packet switched networks based on X.25.  Now, the
telecommunications industry is in transition from X.25 to SS 7; one
of the major issues is how to smoothly connect the new SS 7-based
public switched networks with existing X.25 private networks (and
their associated applications) during this transition.

      This article defines an approach which transparently connects
an X.25 network with an SS 7 network.  The SS 7 Intelligent Network
is loosely composed of three network elements: signalling transfer
points (STPs), service switching points (SSPs), and service control
points (SCPs).  SSPs typically initiate transactions on the SS 7
network, sending queries to SCPs, or establishing the ability to set
up calls within the associated voice network.  SCPs act as the
message routers which connect all the nodes within this network.

      Each of these nodes within the SS 7 network are assigned a
specific network address or signalling point code (SPC).  The SPC is
comprised of three parts:  a network address, a cluster address, and
a member address.  A provision of the SS 7 protocol allows messages
to be routed to an explicit node based on the complete point code, or
the message may be routed to a network cluster address where the
member address is ignored.

      The X.25 packet switched networks allow the different nodes to
attach to one another using Permanent Virtual Circuits (PVCs).  A PVC
is a point to point dedicated long-term session between X.25 network
entities.  The PVC connection may be comprised of multiple
independent channels between the same physical nodes.

      When attempting to communicate across networks, the addressing
schemes are significantly different.  The typical approach is to
alter the application on one network to become aware of the network
topology of the other network.  However, this is cumbersome in terms
of development, network efficiency, and perhaps most importantly,
this defeats the long term objective of migration from one network to
the other.

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