Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1999-03-18
2002-10-08
Hsu, Alpus H. (Department: 2738)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S410000, C370S469000, C379S093010, C379S093070, C379S093310, C709S228000
Reexamination Certificate
active
06463056
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the field of telecommunications switching systems and more particularly to a software application in a switching node that enables the switching node to interpret and manipulate network signaling information from the underlying computer network to which the switching node is attached.
BACKGROUND OF THE INVENTION
An example of a switching system to which the present invention applies is described in U.S. Pat. No. 5,544,163, Expandable Telecommunications System, the contents of which are incorporated by reference herein. A telecommunication switching node described therein has line cards with multiple ports connected to subscriber's telephone lines or to other devices such as PSTN trunks. The switching node also includes a switch/matrix card and at least two system buses for switching calls received on one port to another port in the system. One of these buses is an incoming bus that passes messages from the line cards to the matrix card and the other is an outgoing bus which transmits messages from the matrix card to the line cards.
The telecommunications system also includes a host, i.e., a group of software applications that typically reside on a computer dedicated to those applications. The switching nodes on the system are interconnected by an internodal switching network. A second network termed the “host network,” interconnects the switching nodes and the host computer for supervisory control. The host, the switching nodes and the line cards each includes a software protocol application that processes calls at its level of the system. Specifically, a Layer
5
(L
5
) protocol application in the host manages calls at the host level; a Layer
4
protocol application (L
4
) in the switch manages calls at the switch level; and Layer
3
(L
3
) protocol applications in the line cards handle calls at the line card level of the system.
Traditionally, the L
5
application in the host has managed the L
4
functions in the switch. Thus, when a switch received an incoming request for service from a line card, the request was transmitted from the L
4
application to the L
5
application. In response to the request, the L
5
application instructed the L
4
application on which switching functions to perform. Since the L
5
application was involved in directing nearly all real-time call processing on the switch, the message traffic between the switch and the host was high and this sometimes delayed the transmission of messages between the host and the switch. Moreover, if the host-to-switch link failed or if the host failed, the switch was basically rendered inoperable.
More recently, the L
4
application in the switch was expanded to provide functions previously performed exclusively in the L
5
application. Moreover, the L
4
application was made user-programmable so that a system owner/operator might expand pre-defined L
4
call management operations to accommodate unique call processing requirements. To expand the L
4
functions, the L
4
application is separated into primary and secondary software objects or state machines that are separately dedicated to specific tasks for each “channel” in the switching node. The term “channel” encompasses the data paths between each port and the switch/matrix, and also the software objects in the switch/matrix that directly supervise the use of these paths. Each channel is associated with an instance of the primary L
4
software objects.
Among the primary L
4
software objects are a channel state machine (CH) and a call management state machine (CM). The CH manages state information for its associated channel. This includes information about the states of the other objects in the channel. The CM manages information about the state of any call in its associated channel. An interworking state machine is one of the secondary software objects in the L
4
application. The interworking state machine gives the user the capability to specify the call model on a channel-by-channel basis.
The system described above is usually connected to other telecommunications systems in a broader telecommunications network. The L
3
application receives the underlying network signaling messages in units such as, packets or frames, and it transmits these units to the L
4
application. The signaling messages constitute the distinct control infrastructure that enables provisions of all other services on the network. They enable software applications in the telecommunications network to exchange messages related to call setup and call tear-down and they also enable the exchange of information needed for distributed application processing and network information management. These messages are structured according to specific protocols used by the respective systems on the network. Specifically, there are different types of network signaling protocols, each with its own data formats and standards.
Currently the switch ‘ignores’ most network signaling messages received from the L
3
applications and forwards them to the L
5
application for processing. The L
5
application separates the units, extracts the necessary data and instructs the L
4
application on how to process this data. For requests to other systems, the L
5
application packages the units and forwards them to the L
4
application for transmission to the L
3
applications. Thus, the L
4
application does not process messages in various network signaling protocols without the host intervention. This requires the L
5
application involvement in managing all network signaling messages on the switch and the switch is therefore still unable to process information in these messages when there is a host failure. Moreover, each time a protocol is added to the network or modified, the L
5
application must also be modified to interpret it.
SUMMARY OF THE INVENTION
We have provided novel network protocol data intelligence (NPDI) software in each L
4
application that enables the call processing components in either the L
4
or L
5
application to interpret and manipulate data arranged in different network signaling protocols. The NPDI service manipulates different network signaling protocols and extracts the required messages. It translates these messages into an ‘universal’ internal protocol that is ‘understood’ by L
5
applications and it forwards the messages to an L
5
application for further processing. If an incoming signaling message is to be routed through the switch to another external system, the NPDI service also translates the message from the ‘universal’ protocol into an equivalent message in the protocol of the other system and forwards the message to the corresponding L
3
application for further transmission to that system. Thus, the NPDI provides the means for the L
4
application to convert from one network signaling protocol format to another.
If a new protocol is added to a network, the NPDI translates messages exchanged between host applications and systems using the new protocol. Therefore, host applications may communicate with systems using different protocols without modification to either the host application or the external systems. Thus the NPDI enables the L
4
application to route calls in the switch based on network signaling information transmitted through the L
3
application.
With the foregoing arrangement, the capability of the switch is expanded. The system operator may either configure the switching node to perform call processing functions or have the L
5
application perform these functions. Moreover, we have provided the NPDI with a structure that facilitates addition or modification of network protocols.
More specifically, the NPDI service includes an NPDI function library and one or more protocol awareness applications such as an interworking component. The function library is a collection of functions that provide protocol-independent messages in a ‘universal’/generic data structure to the L
4
and L
5
call processing components. The protocol awareness applications use the function library to translate network signaling
Antarkar Vinayak V.
Hebert Mark P.
Mishra Rajesh K.
Silva Michael C.
Cesari and McKenna LLP
Excel Switching Corp.
Hsu Alpus H.
Qureshi Afsar M.
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