Telephonic communications – Plural exchange network or interconnection – With interexchange network routing
Reexamination Certificate
2001-06-08
2004-01-13
Smith, Creighton (Department: 2645)
Telephonic communications
Plural exchange network or interconnection
With interexchange network routing
C349S200000
Reexamination Certificate
active
06678369
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to telecommunications and more particularly to redundant interfaces for telecommunications in the Signaling System 7 network.
BACKGROUND OF THE INVENTION
In telecommunications systems, data are transmitted between endpoints. Endpoints include, e.g., telephones (including cellular phones), voicemail systems, fax machines, email addresses, and computers.
During transit, the data are processed through various apparatus according to protocols and/or techniques and/or guidelines for switching the data among system components. One such signaling system is called the Signal System #7 (SS7). SS7 implements portions of the International Organization for Standardization (ISO) Open System Interconnection (OSI) seven layer protocol model.
Reliability of data transmission is important for telecommunications systems. Users of telecommunications systems need the data to be transmitted accurately and quickly (e.g., for faxes and telephone conversations). Thus, it is desirable to help ensure that failures in the telecommunications systems do not result in significant losses of data or time to transmit data.
The Signaling System 7 (SS7) network is a packet-based data network used worldwide to support the signaling requirements of modern telecommunications networks. The SS7 network interconnects various pieces of equipment used to provide telecommunications services. Examples of the services supported by the SS7 network include call supervision signaling for the support of local, long-distance, and international calling, signaling for the support of registration, inter-cell handoff, and roaming in wireless (cellular) networks, and transaction-based signaling for the support of enhanced services such as network voicemail, free phone (800-number) calling, caller ID display, pre-paid calling cards, and local number portability.
The SS7 network includes a set of equipment nodes interconnected by sets of signaling data links. The equipment nodes can be classified as either signal transfer points (STPs) or signaling end points (SEPs). The STPs are switches or routers that provide for reliable transfer of signaling packets, or messages, between the SEPs. The SEPs implement the actual telecommunications services described above. Typical signaling end points are telephone switching systems (e.g. Service Switching Points (SSPs)), mobile switching centers (in cellular networks), service nodes (SNs) providing enhanced voice services, database systems holding subscriber information, Intelligent Peripherals (IPs), and Service Control Points (SCPs).
In order to meet the service availability goals for telecommunications equipment/service providers, or in some cases to meet regulatory requirements, stringent reliability requirements are placed on the SS7 network. Signaling nodes must be designed for up to 99.999% availability, equating to less than 6 minutes of down time per year. Each SEP is typically connected to at least 2 STPs, using groups of redundant signaling links that share the traffic load, to guard against the failure of a single signaling link, or even an entire STP, from causing a complete service outage.
SUMMARY OF THE INVENTION
In general, in an aspect, the invention provides a signaling system 7 (SS7) processing system for use in an SS7 network. The system includes a primary interface configured to process communications according to at least one layer of the SS7 protocol stack, the primary interface being configured to provide checkpoint messages relating to the communications and the at least one layer of the SS7 protocol stack, each layer of the at least one layer of the SS7 protocol stack having a corresponding set of information associated with each communication, and a backup interface configured to process communications according to the at least one layer of the SS7 protocol stack, the backup interface being coupled to the primary interface, and configured, to receive the checkpoint messages from the primary interface, wherein the checkpoint messages contain sufficient information for the backup interface to properly process communications that are transferred from being processed by the primary interface to being processed by the backup interface and contain less than all information in each set of information associated with each of the communications corresponding to the at least one layer of the SS7 protocol stack.
Implementations of the invention may include one or more of the following features. The primary interface and the backup interface are each configured to process communications according to at least two layers of the SS7 protocol stack. The primary interface and the backup interface are each configured to process communications according to message transfer part
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(MTP-3), signaling connection control part (SCCP), integrated services digital network user part/telephone user part (ISUP/TUP), and transaction capabilities application part (TCAP) layers of the SS7 protocol stack. The backup interface is configured to initialize the MTP-3, SCCP, ISUP/TUP, and TCAP layers to default conditions. The backup interface is configured to request update checkpoint messages from the primary interface to alter the MTP-3, SCCP, ISUP/TUP, and TCAP layers of the backup interface from the default conditions. The backup interface is configured such that the MTP-3, SCCP, ISUP/TUP, and TCAP layers of the backup interface independently request the update checkpoint messages from corresponding layers of the primary interface. The backup interface is configured to request the update checkpoint messages in response to the backup interface being restored to service. The primary interface is configured to provide the update checkpoint messages intermixed with normal-operation checkpoint messages.
Implementations of the invention may also include one or more of the following features. The checkpoint messages contain only information sufficient for the backup interface to properly process communications that are transferred from being processed by the primary interface to being processed by the backup interface. The at least one layer includes a message transfer part
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(MTP-3) layer and wherein the primary interface is configured to provide a first MTP-3 checkpoint message portion, of a checkpoint message, consisting of a link number and a new link state associated with a signaling link over which the associated communication is transferred in response to the signaling link changing states, and wherein the primary interface is configured to provide a second MTP-3 checkpoint message portion, of a checkpoint message, consisting of an address of a destination signaling point in the SS7 network and an address of a signal transfer point adjacent to the destination signaling point in response to at least one of accessibility of and a preferred route to the destination signaling point changing. The at least one layer includes a message transfer part (MTP) and a signaling connection control part (SCCP) layer and wherein the primary interface is configured to provide, in response to changes in status of the SS7 network, and SCCP network-status checkpoint message portion, of a checkpoint message, checkpointing MTP-pause and MTP-resume local to the primary interface in the SS7 network, SSA and SSP remote from the primary interface in the SS7 network, and subsystem in-service and subsystem out-of-service requests from an application local to the primary interface in the SS7 network. The at least one layer includes a signaling connection control part (SCCP) layer and wherein the primary interface is configured to provide, in response to a communication connection being confirmed or released, an SCCP connection checkpoint message portion, of a checkpoint message, including calling and called SCCP addresses, connection direction, connection service class, source and destination local references, SLS value, and identity of an application local to the primary interface in the SS7 network. The at least one layer includes a transaction capabilities application part (T
DeMent Jeffrey M.
Pierce Tedd R.
Putnam Jeffrey M.
Rothschild Daniel S.
Witt Stephen F.
Mintz Levin Cohn Ferris Glovsky and Popeo P.C.
NMS Communications Corporation
Smith Creighton
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