Abstract:
Telecommunications switching systems that require real-time computer control can be controlled using remotely located computers coupled to the switching systems via data links. By coupling several switching systems to one or more centrally located control computers, maintenance staffing can be reduced while increasing overall system reliability by providing back up control computers in multiple centralized locations. Centrally located control computers can be backed up with redundant computers at the central control site.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This application is a continuation of prior U.S. patent application Ser. No. 10/058,031, filed Jan. 29, 2002, which is a divisional application claiming priority to U.S. patent application Ser. No. 09/075,546, filed May 11, 1998. The entire disclosures of patent applications Ser. Nos. 10/058,031 and 09/075,546 are incorporated herein by reference.  
         [0002]     This invention relates to communication switching networks. This invention could also relate to other computer controlled networks or control systems such as process controls that might be used in a refinery, banking or other networks handling large amount of data or voice information.  
         [0003]     Switching systems networks route thousands of calls, but generally require relatively little computational capability compared to the computational capabilities that are in now-commonly available microprocessors. One critical aspect of switching system reliability however is the control computer(s) that handles routing and switching of calls through the switching system. The typical control architecture in use today is a computer, co-located with the actual switching system. If the controlling computer fails, an entire switching system will be unable to process calls.  
         [0004]     The recent advance of inexpensive, high-power microprocessors and the recent advent of high-speed data links now make it possible to locate high-powered computational capabilities at remote locations. Relatively inexpensive microprocessors can provide significant computer power. With the advent of fiber optic cable, for example, it is now possible to remotely provide substantial computer resources to remote locations.  
         [0005]     A problem with prior art switching system architectures is the possibility of failure of a computer controlling a switching system. If such a computer does fail, either by natural disaster, an act of terrorism, hardware failure or software failure, neither the computer, nor any backup thereto, will be available to perform system-required computational tasks.  
         [0006]     Another problem with prior art switching system control systems is the expense associated with maintenance. In communication networks comprised of numerous switching systems, continuous system availability requires that each system have a competent maintenance staff, which is unnecessary most of the time.  
         [0007]     A method and an apparatus by which computers controlling a switching system can be centrally located, backed up, and where maintenance staff can also be centrally located would reduce the costs required to provide reliable computer resources for controlling switching systems. Maintenance staff could be reduced while improving system reliability. Instead of using costly, special purpose, highly reliable, fault-tolerant computers, less costly computers could be used without sacrificing network availability because control computer reliability can be achieved with several less expensive computers at several backup locations.  
       SUMMARY OF THE INVENTION  
       [0008]     There is provided herein, a method and an apparatus for centrally locating computers used to control telecommunications switching systems.  
         [0009]     A network of switching systems is comprised of switching hardware and a control computer. In these systems, the call processing control can be performed by a central computer coupled to the switching system through an appropriate data link between the centrally located control computer and the switching system.  
         [0010]     Call processing message traffic that is exchanged between a co-located computer and the switching system circuitry is coupled to a data link. The data link is coupled to a suitably programmed centrally located control computer such that the centrally located control computer exchanges the call processing data with the switching system through the data link. The remotely located control computer can effectively carry out all call processing functions for the switching system.  
         [0011]     In the preferred embodiment, most call processing data is available via a separate signaling network such as AT&amp;T&#39;s SS7 network that couples multiple switching systems together and which is connected directly to the centrally located control computer. In-band signaling data such as dual tone multi-frequency (DTMF) signals, and/or dial pulses, which originate in the switching network needs to be sent to the centrally located computers. In-band signaling data uses the data link that connects the remote control computer to the switching systems.  
         [0012]     Redundant backup computer capability can be co-located to the centrally located control computer or at a different location. Several communication systems can be controlled from a single location by appropriate data links between the systems and the centrally located control computer. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  shows a simplified block diagram of four switching systems controlled by a plurality of control computers remotely located from the switching systems.  
         [0014]      FIG. 2  shows a block diagram of centralized control architecture for a plurality of switching networks coupled to centrally located control computers. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     The detailed description of the invention disclosed in the U.S. patent application Ser. No. 08/808,298 for a “Distributed Network Control and Fabric Application Interface” filed Feb. 28,  1997  and assigned to AT&amp;T is hereby incorporated by reference. A method and apparatus for coupling a switching system to a remote control computer is disclosed therein.  
         [0016]      FIG. 1  shows a simplified block diagram of a switching system control architecture  100  whereby computer control of multiple switching systems is provided by remotely located computers  122 ,  124 ,  126 .  
         [0017]     In  FIG. 1 , four (4) switching systems  102 ,  104 ,  106 ,  108  known as Lucent Technologies, Inc. No. 4 ESS™ switching systems are coupled to call processing and control computers  122 ,  124 ,  126  through data links  112 ,  114 ,  116 , and  118 . The data links  112 ,  114 ,  116  and  118  operatively couple control computers  122 ,  124 , and  126  to the switching systems  102 ,  104 ,  106  and  108 . In instances where other switching systems are used as switching systems  102 ,  104 ,  106  and  108 , such as a Lucent Technologies No. S ESS™ a terminal adapter (not shown) might be required between the switching systems and an asynchronous transfer mode switching system  120  coupling the switching systems  102 ,  104 ,  106  and  108  to the control computers  122 ,  124 , and  126 .  
         [0018]     In the preferred embodiment, the operative coupling between the switching systems  102 ,  104 ,  106  and  108  and the control computers  122 ,  124 ,  126  is accomplished using an asynchronous transfer mode (ATM) interface, well-known to those skilled of the telephony art. As set forth more fully below, and as shown in  FIG. 2 , other protocols might also be used as well. Synchronous data transfer or Transmission Control Protocol/Internet Protocol (TCP/IP) protocols could also be used. Call processing data that is normally exchanged between a co-located computer for each of the switching systems  102 ,  104 ,  106  and  108 , is interfaced to the data links  112 ,  114 ,  116  and  118 .  
         [0019]     In a No. 4 ESS™ the 1B processor controlling the No. 4 ESS™ is coupled to switching system peripheral equipment through an interface bus, also known as the IFB. Call processing and control computers  122 ,  124 ,  126  communicate with the No. 4 ESS™ through data links  112 ,  114 ,  116 , and  118  that are operatively coupled to the IFB. The IB processor controlling the No. 4 ESS™ also communicates to peripheral equipment over the IFB. Call processing data is thereby available in a No.4 ESS™ from the IFB and an appropriate electrical interface to that allows call-processing signals to be captured from the IFB.  
         [0020]     In  FIG. 1 , data links  112 ,  114 ,  116  and  118  are high speed asynchronous transfer mode or ATM data links between the switching systems remotely located from a building site  2 ,  110  wherein control computers  122 ,  124 ,  126  provide the control functions to the switching systems  102 ,  104 ,  106  and  108 . In instances where the switching systems  102 ,  104 ,  106  and  108  consist of Lucent Technologies No.4 ESS™ switching systems, an appropriate electrical interface to the IFB of the switching systems  102 ,  104 ,  106  and  108  would of course need to translate IFB signals to an asynchronous transfer mode. If switch  120  is a TCP/IP protocol switch (not shown) instead of ATM as shown, switches  102 ,  104 ,  106 ,  108  would require an appropriate TCP/IP protocol interface. In instances where the switching systems  102 ,  104 ,  106  and  108  are No. 4 ESS™ systems, the switching fabric interface (SFI) provides the appropriate interface.  
         [0021]     Those skilled in the art will recognize that one or more of the ATM links  112 ,  114 ,  116 ,  118  between the switching systems and the control computers could just as easily be replaced with synchronous data links between the switching systems  102 ,  104 ,  106 , and  108  and the control computers, such as a TCP/IP link protocol mentioned above. As shown in  FIG. 1 , an asynchronous transfer mode switch  120  is required to couple the ATM links  112 ,  114 ,  116 , and  118  to the control computers  122 ,  124 ,  126 . The ATM switch is programmed to accept asynchronous transfer mode cells and to route the cells between the switching systems  102 ,  104 ,  106 ,  108  and the control computers  122 ,  124 ,  126 . ATM and ATM switching is well-known in the art.  
         [0022]     One appropriate computer might handle the call processing computing for several switching systems, however, for purposes of system reliability, back up computers are typically employed to provide enhanced system reliability. In  FIG. 1 , computers  124 , and  126  provide redundant, back-up computing to a control computer  122 . The control system architecture described in U.S. patent application Ser. No. 08/808,298 filed Feb. 28, 1997 for a “Distributed Network Control and Fabric Application Interface” is incorporated by reference herein.  
         [0023]     The physical media used for the data links  112 ,  114 ,  116  and  118  are preferably optical fiber, however a microwave link, coax cable, or even a twisted pair of wires, or XDSL (any digital subscriber link) could be used for the data links shown in  FIG. 1 . Those skilled in the art will recognize that any appropriate signaling protocol might be used over the asynchronous transfer mode (ATM) link.  
         [0024]     In the apparatus depicted in  FIG. 1 , a single control computer provides the computational capabilities required for the call processing of several switching systems. By using a single remote computer, preferably backed up for enhanced system reliability, overall system reliability can be enhanced while reducing maintenance costs attributable to maintenance staff required for each switching systems  102 ,  104 ,  106  and  108 .  
         [0025]      FIG. 2  shows a network of centrally controlled switching systems as alternate embodiments of the architecture and a furtherance of the singular architecture disclosed in  FIG. 1 . In  FIG. 2 , in building site  1 ,  206  there is a first network of communication switching systems  202  under the control of remotely located control computers operatively coupled to such computers  208 ,  210 ,  212 , (depicted as SPPs in  FIG. 2 ) via an asynchronous transfer mode switch  204  and ATM data link  203 . Call processing and control signals from the switching networks  202  is exchanged with the control computers  208 ,  210 ,  212 , remotely located with respect to the switching system  202 , via the ATM switch  204  and the ATM data links  203 . The computers  208 ,  210 ,  212  provide call processing and control functions to the network of switching systems  202  by ATM communications between the switching systems  202  and the computers  208 ,  210 ,  212 . In addition to using asynchronous transfer mode data transfer, so-called TCP/IP protocols might be used as well.  
         [0026]     For network reliability, the switching systems being controlled have redundant control links to other building sites. In  FIG. 2 , a switching system  224 -A has two links: a primary” control link  295  to building site  2 ,  216  and an alternate link  295 -A to another control site, building site  3 . Similarly, switching system  224 -B has a primary link  299  to building site  2  but an alternate link  299 -A to building site  1 ,  206 . Back-up link  293  couples a switching system  236  to the ATM/synchronous network  209  of building site  4 ,  246 . In the event a building site is destroyed for example, back-up control sites established through such links using appropriate media significantly improve system reliability.  
         [0027]     A network manager controller  291  monitors loading and usage of all of the ATM switching nodes  218 ,  228 ,  204 ,  209 , communication links between the nodes ( 226  and  242  for example) and controlling computers (e.g.,  220 ,  208 ,  210 ,  212 ,  232 ,  234 ) for the switches. The network manager  291  can reconfigure loading of the nodes, including if necessary, enlisting other controlling computers (e.g.  208 ) to efficiently manage loading throughout the network shown in  FIG. 2 .  
         [0028]     Those skilled in the art will recognize that one computer,  208  for instance, of the computers  208 ,  210 ,  212  might provide supervision and control of all of the switching systems  202  remotely located with respect to the control computers  208 ,  210 ,  212 . The other computers  210 ,  212  might provide fault tolerant redundant back-up to the computer  208  controlling the switching network. Alternatively, computers  208  and  210  could control switching systems  202  and control computer  212  could be used as a backup.  
         [0029]     Alternate embodiments of the invention disclosed above and that are shown in  FIG. 2  would include linking the ATM switch  204  to another ATM switch  218  at another central control site  216  for another network of communications switches  224  via another ATM data link  214 . As shown, ATM switch  218  couples a single, remotely located call processing/control computer  220  for a second network of switches  224 . The computers  208 ,  210 ,  212  of the first site  206  could provide back up control functionality for the single computer  220  of the second site  216  via the ATM data link  214 . Similarly, using an appropriate data link  214 - 1 , these computers  208 ,  210 ,  212 , could provide back-up for the computer  291  controlling an ATM/synchronous switch  209  within a fourth building site,  246 .  
         [0030]     In the second site  216 , the ATM switch  218  is captioned as an ATM-sync switch to show that ATM communications between the first control site  206  and the second control site  216  might be converted to a synchronous format by the ATM switch  218 . In the second control site  216 , located at building site  2 , communications between the second network of switches  224  might be ATM format, however, communications between the switches of the network  224  and the control computer  220  might be synchronous as well. Depending upon the particular switches  224  being used, other electrical interfaces might be required to couple the switches  224  to remotely located control computers. Certain switches, such as Lucent Technologies No. 5 ESS used in place of the 4 ESS, might require other electrical interfaces to couple them to remotely located control computers. Certain switches, such as Lucent Technologies No. 5 ESS™, might require a terminal adapter to couple the switch to an external control computer. Other switches with other control architectures might require other electrical interfaces.  
         [0031]     Yet another alternate embodiment includes a synchronous communications link  226  operatively coupling the second control site  216  to a third control site  238 . A synchronous switching system  228  within the third control site  238 , which again is remotely located from a third set of communications systems  236 , synchronously links the communications systems  236  to control computers  230 ,  232 ,  234  via an appropriate synchronous communication link  240 . The computers  230 ,  232 ,  234  within the third control site  238  might also provide backup computer control capability to the previously described communication networks,  202 ,  224  via communications links described above.  
         [0032]     A suitable synchronous communications link  242 , operatively couples the aforementioned remote control computers for the communication system  202 ,  224 ,  236  to yet another remote site  246  where control and command of another communication network  248  is located.  
         [0033]     Those skilled in the art know that the 1B processor used with the Lucent Technologies, Inc. No. 4 ESS™ switch has spare ports on the IFB. These spare ports allow for system growth and provide access to the switching system for remote control computers.