Telephonic communications – Plural exchange network or interconnection – Interexchange signalling
Reexamination Certificate
2002-11-14
2004-09-21
Matar, Ahmad F. (Department: 2642)
Telephonic communications
Plural exchange network or interconnection
Interexchange signalling
C379S230000
Reexamination Certificate
active
06795546
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the distribution and processing of messages in a communications network. More particularly, the present invention relates to methods and systems for distributing messages among multiple processors for stateful or sequenced processing of the messages on a per-sequence basis.
BACKGROUND ART
Within a signaling system
7
(SS7) communication network call setup and teardown information is conveyed using ISDN user part (ISUP) messages. Typically, all ISUP messages associated with the same call or “circuit” are routed along the same signaling path between the originating and terminating offices involved in the call. The routing of these ISUP messages is commonly performed by SS7 signal transfer point (STP) routing nodes that reside in the network. As signaling networks have evolved, STP nodes have increasingly been used to perform message processing functions in addition to basic message routing functionality. One example of such message processing is SS7 global title translation (GTT), which is performed on class 0 signaling connection control part (SCCP) messages transmitted through a signaling network. For SCCP messages, protocol class 0 identifies a service class characterized by connectionless service for which sequencing is not required.
FIG. 1
is a block diagram of an exemplary STP node
100
that performs internal GTT processing on SCCP messages. STP
100
employs a distributed, multi-processor architecture, which allows a number of independent processor cards to simultaneously receive and process SS7 signaling messages. More particularly, STP
100
includes an interprocessor message transport bus
102
, a pair of maintenance and administration subsystem processors
104
, a first SS
7
link interface module (LIM)
110
, a second LIM
112
, a first GTT processor
120
, and a second GTT processor
122
. As generally indicated in
FIG. 1
, an SCCP message received at LIM
110
may be identified as requiring GTT processing and may be directed to GTT processor
122
. GTT processor
122
performs GTT address translation on the received SCCP message and determines the routing prior to directing the message to outbound LIM
112
for transmission.
In STP
100
illustrated in
FIG. 1
, GTT processors
110
and
112
are identically provisioned so as to be operated in a load-sharing manner. That is, an inbound or receiving LIM module distributes received SCCP messages to a GTT processor based on the available capacity of each active GTT processor module in the system. Load-sharing among multiple redundant processors is advantageous for non-stateful processing of messages. For example, GTT processing of class 0 SCCP messages requires only that a received SCCP message be translated and routed to a final destination based on the translated address. Once the GTT processor performs an address translation and directs the SCCP message to an outbound LIM, that particular address translation is of no significance to translation operations performed on SCCP messages subsequently received by the STP. Hence, GTT processing of class 0 SCCP messages is not stateful in nature, and a relatively simple load-sharing algorithm may be employed to handle internal SCCP message distribution within a multi-processor STP. For example, class 0 SCCP message may be load-shared among GTT processors on a per-message basis using any suitable message-based distribution function.
In contrast to class 0 SCCP messaging, ISUP message processing can be both stateful and sequenced. As used herein, the term “stateful processing” refers to processing where state information must be stored by a processor in order to process messages relating to the same transaction. The term “sequenced processing” refers to processing that requires messages to be processed, sent or received in a particular sequence.
FIG. 2
is a simplified call setup scenario involving a sample telecommunication network
150
that includes a calling party
152
, a called party
154
, an originating end office exchange
156
, a tandem office exchange
158
, a terminating end office exchange
160
, and three STP nodes
162
-
166
. When calling party
152
completes the dialing of digits associated with called party
154
(i.e., 851-2345), originating exchange
156
selects and reserves a voice trunk for the call. In this example, the selected voice trunk terminates at tandem exchange
158
. As such, an ISUP initial address message (IAM) is generated by originating exchange
156
and transmitted via STP nodes
162
and
164
to tandem exchange
158
. This IAM message includes information necessary for the intermediate tandem exchange
158
to complete the call setup operation. Upon receipt of the originating exchange generated IAM message, tandem exchange
158
secures the voice trunk to exchange
156
and subsequently reserves a voice trunk to terminating exchange
160
. Tandem exchange
158
then generates an ISUP address complete (ACM) message, which is transmitted back to the originating exchange, and a second IAM message (i.e., IAM*), which is transmitted to the terminating exchange
160
in a manner similar to that described above.
Sometimes all of the dialed digits needed to initiate the call setup sequence are not transmitted in the IAM message. For example, the ITU ISUP protocol employs a subsequent address message (SAM) and a subsequent directory number message (SDM) to carry additional called party (CdPA) information in addition to that provided in an IAM message. A detailed description of the ITU ISUP protocol may be found in ITU publications Q.
761
Signaling System No.
7-ISDN User Part Functional Description, 12/1999 and Q.762 Signaling System No. 7-ISDN User Part General Functions Of Messages And Signals, 12/1999, the disclosures of which are herein incorporated by reference in their entirety.
FIG. 3
illustrates sample telecommunications network
150
and a portion of the ITU ISUP signaling involved in a call setup operation. In this signaling example, an IAM message is transmitted by the originating exchange
156
after the calling party
152
has dialed a sufficient number of digits (e.g., calling party dials “851”) to enable the exchange
156
to determine which voice trunk to select. The remaining dialed digit information necessary to complete the call setup is communicated to the tandem office
158
via one (or more) SAM messages, as indicated in FIG.
3
.
The scenario described above and illustrated in
FIG. 3
is an example of a signaling scenario that presents significant problems for stateful and/or sequenced processing of the messages. Unlike the GTT processing of class 0 SCCP messages, where all of the information necessary to process a received message is present in that message, an ISUP processing application may require that multiple, related messages (e.g., IAM, SAM, SDM messages) be collected and analyzed before stateful and/or sequenced processing can be successfully completed. For example, commonly assigned co-pending U.S. Patent Publication No. US 2002/0054674 (hereinafter, the '674 Publication), the disclosure of which is incorporated herein by reference in its entirety, discloses methods and systems for providing triggerless intelligent network screening services based on stateful and sequenced processing of call setup messages. In one embodiment of the invention disclosed in the '674 Publication, a triggerless screening service routing node, such as an STP, screens call setup messages, such as ISUP messages, and provides intelligent network services. Examples of intelligent network services provided include calling party screening, called party screening, charged party screening, and redirecting party screening. Each of these applications may utilize dialed digits collected from call setup messages to make a screening decision. If the dialed digits are sent in multiple messages, processing of the multiple messages may be stateful because processors may remember the state of a call in order to determine the message to be expected next. For example, after r
Delaney Robert J.
Hildebrand John L.
Marsico Peter J.
Jenkins & Wilson & Taylor, P.A.
Matar Ahmad F.
Nguyen Quynh H.
Tekelec
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