Patent Application
20070047539
The subject matter described herein relates to the distribution and processing of messages in a communications network. More particularly, the subject matter described herein relates to methods, systems, and computer program products for preserving sequencing of signaling messages at a routing node.
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 triggerless location portability processing, which may be performed on ISUP messages.
A location portability lookup, also referred to as a reverse number portability lookup is a lookup based on the calling party digits in a message. Such a lookup may be required when a ported subscriber is calling another subscriber and it is desirable to determine the calling party directory number from the location routing number stored in the calling party number field of the ISUP message.
ISUP messages may require sequenced processing at a routing node such as an STP node. Examples of ISUP messages that may require sequenced processing at a routing node include ISUP initial address message (IAM) messages. An IAM message can be utilized in a call setup operation. One example of processing that may be performed at an STP for an IAM message is a location portability lookup.
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 SAM message 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, December 1999 and Q.762 Signaling System No. 7-IDSN User Part General Functions Of Messages And Signals, December 1999, the disclosures of which are herein incorporated by reference in their entirety. Thus, the information provided via one (or more) ISUP messages (e.g., IAM, SAM, SDM messages) may be necessary in order to complete the call setup.
Further, an ISUP processing application may require that such multiple, related 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 sequenced processing of call setup messages. In one embodiment of the subject matter 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. Such processing may be sequenced in that IAM and SAM messages must be received, processed, and transmitted in order.
In order to ensure sequenced processing, routing nodes have been implemented to require processing related call setup messages with the same processor or that call setup information from one processor be forwarded to another processor in order. In certain cases, SAM messages may not require the processing that is required by their related IAM messages. In general, such message processing scenarios involve applications or services that do not require or make use of the subsequent dialed digit information contained in a SAM message. Examples of such signaling message processing scenarios include processing related to certain pre-paid calling services and processing related to certain location portability services. More particularly, the relevant scenarios include those pre-paid, location portability applications and services that require only calling party number (CgPN) information associated with a call. In these cases, an IAM message contains the complete CgPN identifier, and internal communication and processing bandwidth in a routing node may be wasted as a result of requiring all associated SAM messages to be unnecessarily sent to an application service processor.
Another problem with requiring that messages that are part of the same transaction follow the same path in a routing node is that messages relating to the same transaction must be correlated. Such correlation requires that the distributing processor maintain state for each transaction. Requiring the distributing processor to maintain state unnecessarily consumes routing node processing resources.
Accordingly, there exists a need for improved methods and systems for preserving sequencing of ISUP IAM and SAM signaling messages at routing nodes.
According to one aspect, the subject matter described herein comprises methods, systems, and computer program products for sequencing call setup messages in a routing node that includes a triggerless call setup message processing application. One method includes receiving first and second signaling messages at a routing node of a communications network. The first signaling message is received prior to the second signaling message. Next, it is determined whether processing is required for the first signaling message. In response to determining that processing is required for the first signaling message, first and second sequence identifiers are assigned to the first and second signaling messages, respectively. The first and second sequence identifiers indicate a relative sequence for routing the first and second signaling messages. Next, the first and second signaling messages are communicated to the communications network according to the relative sequence specified by the first and second sequence identifiers.
The subject matter described herein for preserving sequencing of signaling messages may be implemented using a computer program product comprising computer executable instructions embodied in a computer readable medium. Exemplary computer readable media suitable for implementing the subject matter described herein include disk memory devices, programmable logic devices, application specific integrated circuits, and downloadable electrical signals. In addition, a computer readable medium that implements the subject matter described herein may be distributed across multiple physical devices and/or computing platforms.
Exemplary embodiments of the subject matter will now be explained with reference to the accompanying drawings, of which:
According to one embodiment, the subject matter described herein includes a communications network routing node, such as a signal transfer point (STP), configured to process, route, and preserve the sequencing of signaling messages such as ISDN user part (ISUP) initial address messages (IAMs) and ISUP subsequent address messages (SAMs). Further, according to one embodiment, the subject matter described herein can provide triggerless location portability (TLP) and triggerless pre-paid screening (TPS) processing of IAM messages and preserve sequencing of the IAM messages and SAM messages. The EAGLE® STP, the IP7® Secure Gateway, and the TEKSERVER® platform (all available from Tekelec of Calabasas, Calif.) are suitable systems for processing and preserving sequencing of signaling messages according to the subject matter disclosed herein.
Processing applications 114 and 116 illustrated in
For simplicity of illustration, only two LIMs 104 and 106, two DSMs 108 and 110, and one DCM 112 are illustrated in
HMDC function 206 can receive an incoming signaling message from the lower processing layers and determine whether the message is addressed to and consequently requires processing by one or more processing applications in STP node 100. Application screening and sequencing function 208 can examine an incoming signaling message, which may not be addressed to STP node 100, and determine whether the message requires processing by processing application, such as processing applications 114 and 116 (shown in
For messages such as IAM and SAM messages, the order in which the messages should be transmitted from STP 100 is the order in which the signaling messages are received. In other words, these signaling messages should be transmitted in a FIFO order. In one exemplary implementation, after processing by an application on a DSM, a message may be returned to an originating LIM and stored in buffer 204. Application screening and sequencing function 208 may control the sending of messages from I/O buffer 204 such that messages with sequence number 2 is returned to I/O buffer 204 before a message with sequence number 1, the message with sequence number 2 will be buffered until the message with sequence number 1 is returned to the LIM after processing by one of applications 114 and 116. Once the message with sequence number 1 is returned, the LIM may send the message with sequence number 1 followed by the message with sequence number 2 to the outbound signaling link.
In an alternate embodiment, rather than returning messages to the originating LIM and buffering the messages at the originating LIM before sending the messages to the LIM or DSM associated with the outbound signaling link, the messages may instead be forwarded directly to the LIM or DCM associated with the outbound signaling link after processing by a DSM application. In such an implementation, the LIM or DSM associated with the outbound signaling link may include an application screening and sequencing function that buffers and sends messages over the outbound signaling link according to the sequence numbers assigned by the receiving LIM or DCM.
As stated above, maintaining proper sequencing of ISUP IAM and SAM messages in a distributed processing environment such as STP node 100 can be important so that these messages are not dropped at their destination.
If it is determined the received signaling message is an ISUP message (i.e., the SI value is 5), function 208 can examine a message type parameter contained in the message to determine whether the message is an IAM message or a SAM message (step 306). A message type parameter of 1 indicates that the message is an IAM message, and a message type parameter of 2 indicates that the message is a SAM message. Referring to
In order to guarantee such sequencing, if a received message is determined to be an IAM message at step 306, a sequence identifier can be assigned to and associated with the signaling message (step 308). The sequence identifier for the IAM message can be a number or other alphanumeric character that is one greater than or one less than a number or character of the sequence identifier assigned to the IAM or SAM message received by a LIM or DCM immediately before the currently received IAM message. As a result, a sequence identifier is assigned to the IAM message such that the receipt order of the IAM message with respect to other IAM and SAM messages received by the same LIM or DCM can be known by the sequence identifiers of the IAM and SAM messages.
After a sequence identifier has been assigned and associated with the IAM message, the IAM message can be forwarded to one of a plurality of the application processors in STP node 100 for further processing (step 310). For example, further processing of the IAM message may include, but is not limited to, triggerless pre-paid services processing or location portability processing by a triggerless location portability (TLP) processing application, such as one of processing applications 114 and 116. After location portability processing of the IAM message, the IAM message can be returned to LIM 104 or forwarded to another module, such as LIM 106, for outbound communication (step 312).
LIM 104 can receive the IAM message and check the sequence identifier associated with the IAM message to determine whether all messages with preceding sequence identifiers have been transmitted to their destination (step 314). If all messages with preceding sequence identifiers have not been transmitted, the IAM message can be buffered at LIM 104 until all messages with preceding sequence identifiers have been transmitted (step 316). One reason that messages received by an originating LIM may be misordered is that IAM messages may require internal processing within STP while SAM messages may not. Thus, without the subject matter described herein, a SAM message may be received and routed while the corresponding IAM message is being processed. To avoid sending such messages to their destination out of sequence, after all of the IAM messages with preceding sequence identifiers have been transmitted, the IAM message can be routed to its destination (step 318). Routing the message to its destination may include performing a lookup in a route table on the originating LIM, identifying an outbound LIM associated with the outbound signaling link, and forwarding the message to the outbound LIM or DCM.
As stated above, instead of buffering the IAM message at LIM 104, the IAM message can be buffered at any suitable component of STP node 100 to await outbound transmission. For example, the IAM message can be buffered by outbound LIM 106, outbound DCM 110 or any suitable LIM, DSM, or DCM of STP node 100.
Referring again to step 306, if a received message is determined to be an SAM message, a sequence identifier can be assigned to and associated with the SAM message (step 320). Similar to the assignment of sequence identifiers to IAM messages, the sequence identifier for the SAM message can be a number or other alphanumeric character that is one greater than or one less than a number or character of the sequence identifier assigned to the IAM or SAM message received immediately before the currently received SAM message. As a result, a sequence identifier is assigned to the SAM message such that the receipt order of the SAM message with respect to other IAM and SAM messages can be known by the sequence identifiers of the IAM and SAM messages. Because the SAM message does not require location portability processing, the SAM message does not require transmission to one of the processing applications as required for the IAM message. Further, sequencing of the SAM message with respect to an associated IAM message is preserved by the assignment of sequence identifiers to the messages and making sure that the messages are transmitted from STP 100 in order based on the sequence numbers.
After a sequence identifier has been assigned and associated with the SAM message, LIM 104 can check the sequence identifier associated with the SAM message to determine whether all messages with preceding sequence identifiers have been transmitted to their destination (step 322). If all messages with preceding sequence identifiers have not been transmitted, the SAM message can be buffered at LIM 104 until all messages with preceding sequence identifiers have been transmitted (step 324). After all of the messages with preceding sequence identifiers have been transmitted, the SAM message can be routed to its destination (step 318). Routing the message to its destination may include performing a lookup in a route table on the originating LIM, identifying an outbound LIM associated with the outbound signaling link, and forwarding the message to the outbound LIM or DCM.
As stated above, instead of buffering the SAM message at LIM 104, the SAM message can be buffered at any suitable component of STP node 100 for awaiting outbound transmission. For example, the SAM message can be buffered by outbound LIM 106, outbound DCM 110 or any suitable LIM, DSM, or DCM of STP node 100.
Referring generally to reference B of
Referring generally to reference B of
At reference E, SAM message 602 may be stored at a buffer 614 of LIM 612 until IAM message 600 is received at LIM 612 for outbound communication. LIM 612 can determine that SAM message 602 should be maintained in buffer 614 because SAM message 602 is associated with a sequence identifier (i.e., value 2) that is after the sequence identifier (i.e., value 1) associated with IAM message 604. IAM message 604 may also be buffered at buffer 614 until all preceding messages have been transmitted. Accordingly, when all preceding messages have been transmitted, IAM message 600 followed by SAM message 602 can be transmitted from STP 604 (reference F). As a result, IAM message 600 and SAM message 602 are transmitted from STP 604 in the sequence that the messages were received. Thus, although IAM message 600 required further processing, SAM message 602 was buffered until it could be sent in an FIFO order with IAM message 600.
According to one embodiment, buffer 614 may also maintain IAM and SAM messages received at a plurality of inbound modules of STP node 604. Thus, messages forwarded to LIM 612 for outbound communication may be from one a plurality of inbound modules. In order to assure that sequencing numbers for buffering the messages at buffer 614 are confused with one another, a second sequencing number may be assigned to the message based on the inbound module associated with the message. As described herein, message may be communicated from LIM 612 in a FIFO based on the first sequencing number assigned to the message at the inbound module. In addition, the messages may be communicated from LIM 612 in a round robin fashion based on the second sequencing number assigned to the message. Thus, the sequencing numbers assigned at the inbound modules are not confused with one another because messages are associated with an additional sequencing number corresponding to its corresponding inbound module.
Accordingly, one advantage of the subject matter disclosed herein is that messages are transmitted from an STP node in a FIFO order, even when some messages require internal processing and others do not. This feature is important for messages that are related and require communication to their destination in the order that the messages were received at the routing node. Although the above examples relate to ISUP IAM and SAM messages, the subject matter described herein can be applied to any signaling message, such as any type of MTP, SIGTRAN, or IP telephony message, requiring FIFO sequencing at a network node.
As described above, preserving proper sequencing of ISUP IAM and SAM message can be important in order to avoid message dropping. The subject matter disclosed herein can provide proper sequencing of ISUP IAM and SAM messages through an STP node. Further, SAM messages are not required to follow associated IAM messages through processing in STP node in order to maintain proper sequencing. As a result, internal bandwidth consumption in the STP node is reduced. Further, IAM messages may be load-shared among multiple location portability processing applications while maintaining proper outbound sequencing. Moreover, correlation of signaling messages is not required to preserve sequencing.
It will be understood that various details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation, as the invention is defined by the claims as set forth hereinafter.
