Abstract:
An action control point master gatekeeper for a communications network creates a hierarchical scalable signaling and transaction infrastructure for supporting carrier level deployment of, for example, IP telephony using H.323 terminals and gateways. The action control point master gatekeeper supports a plurality of H.323 zones in an administrative domain. Action control point master gatekeepers in an administrative domain can signal to other administrative domains via a hierarchical signaling infrastructure. A backup master gatekeeper can also be present in an action control point. A customer database, which can be distributed within zones or centralized within an administrative domain, allows for address resolution between a terminal alias and a terminal address. The customer database can also contain pointers to special purpose processes, such as network control points, to implement service specific transaction services.

Description:
FIELD OF THE INVENTION 
     The invention relates to communication networks. More particularly, the invention relates to an action control point master gatekeeper for use in a communications network. 
     BACKGROUND OF THE INVENTION 
     A communications network can transmit packets of digital information between computers using a protocol, such as Internet Protocol (IP). An increasingly popular use of IP is to transmit audio, video and other multimedia communications between people. For example, a person can use an IP terminal, such as a personal computer connected to an IP network, to speak with another person with an IP terminal. The use of IP terminals to transmit voice communications, similar to the use of a standard telephone, is called IP telephony. As IP networks and IP terminals become faster and more powerful, the use of IP telephony is expected to dramatically increase. 
     A set of procedures, known as “H.323,” are being developed to provide a foundation for audio, video and data communications over IP based networks. The H.323 procedures, such as those dated May 1996, are an umbrella recommendation from the International Telecommunications Union (ITU) to describe terminals, equipment and services for multimedia communication over a Local Area Network (LAN) that does not provide a guaranteed quality of service. Such networks are important because they are commonly used in offices, and include packet-switched Transmission Control Protocol/Internet Protocol (TCP/IP) and Internetwork Packet Exchange (IPX) over Ethernet systems. 
     FIG. 1 illustrates a communications system, or “zone,”  100  according to known H.323 procedures. The zone  100  includes a number of “terminals”  110 , such as personal computers equipped with microphones and speakers, that provide for real-time, two-way communications with another terminal  110 . Each terminal  110  is associated with a terminal address, such as an IP address, which is used to address communications to that terminal  110 . According to H.323 procedures, a terminal  110  must provide audio capability, and may also provide video and/or data capabilities, if desired. The terminals  110  communicate with other entities in the zone  100  over a communications network, such as an IP network. The IP network would typically connect, for example, several terminals  110  in a single office. 
     The zone  100  may include one or more “gateways”  120 ,  130  which provide real-time, two-way communications between terminals  110  in the zone  100  and the Public Switched Telephone Network (PSTN). The gateways  120 ,  130  can also communicate, for example, with another gateway to provide IP telephony with terminals located in another zone (not shown in FIG.  1 ). 
     A “gatekeeper”  140  provides address translation, control access and, if desired, bandwidth management in the IP network for other H.323 entities in the zone  100 . Suppose, for example, a person using a terminal  110  in the zone  100  wants to establish an IP telephony call to a co-worker who also has a terminal in the same zone. The person enters the co-worker&#39;s “terminal alias” using the terminal  110 , and the terminal alias is sent to the gatekeeper  140 . The terminal alias could be, for example, the co-worker&#39;s name, title, telephone number, e-mail address or Web page. The gatekeeper  140  translates the terminal alias into a terminal address, such as an IP address, associated with the co-worker&#39;s terminal so that the IP telephony call can be established. 
     As shown in FIG. 1, the zone  100  can include several IP segments that communicate using routers  150 . The zone can also include a “Multipoint Control Unit” (MCU)  160  which enables three or more terminals  110  and gateways  120 ,  130  to participate in a multipoint conference. As used herein, the general term “H.323 entity” refers to any H.323 component, such as, for example, a terminal  110 , a gateway  120 ,  130 , a gatekeeper  140  or an MCU  160 . The zone  100  is the collection of H.323 entities and must include at least one terminal  110 . 
     There are several problems with the use of H.323 procedures for IP telephony. One problem is that the procedures cannot be easily “scaled,” or applied to larger systems. For example, the gatekeeper  140  must provide address translation for each terminal  110  in the zone  100 . If, however, a person wants to contact someone in a different zone, there is no easy way to do this when a large number of users are involved. A person may want to contact one of hundreds of thousands, or millions, of other people using a terminal alias. It is not feasible to have a single gatekeeper  140  translate a terminal alias for that many users. The amount of information that would have to be stored is extremely large, and searching the information would be very time consuming. Moreover, databases for every gatekeeper in every zone would need to be constantly updated when any terminal alias or terminal address, in any zone, was changed. The maintenance and synchronization required for such a task is not practical. 
     Another disadvantage with the use of H.323 procedures is communications service features associated with traditional telephone service, such as the features provided by a global virtual network service, cannot be provided to IP telephony users. For example, a business may want to prevent some users from placing a telephone call outside of a “virtual” private network, which can include a number of different zones. In the traditional circuit switched network, such a call would be considered an “off network” call. 
     Suppose a company has offices in New York and Washington, each being supported by a different H.323 zone. The company may want to let an employee in the Washington office call other employees in the Washington office and other employees in the New York office. The gatekeeper for the Washington office, however, would not normally know the terminal alias and terminal address of each employee in the New York office. The problem obviously becomes more acute as more employees, offices and zones are added. 
     Other communications service features that businesses will expect include, for example, associating a password or client number with a telephone call, voice mail, and the use of calling cards. In addition to businesses, consumers have come to expect such communications service features. Moreover, an IP network carrier will need to be able to introduce new features rapidly to a large number of customers. 
     Still another drawback with the use of H.323 procedures for IP telephony is that only one gatekeeper  140  is present in each zone  100 . If the gatekeeper  140  becomes unavailable, such as, for example, when the computer breaks down, communications in that zone  100  will come to a halt. This will make IP telephony unreliable. 
     In view of the foregoing, it can be appreciated that a substantial need exists for a method and apparatus allowing for a scalable, reliable and flexible IP telephony system, and for solving the other problems discussed above. 
     SUMMARY OF THE INVENTION 
     The disadvantages of the art are alleviated to a great extent by an action control point master gatekeeper. In one embodiment of the present invention, an action control point is used in a communications network that has a gatekeeper able to generate an address inquiry, including a terminal alias. The action control point has a customer database that associates the terminal alias with a terminal address. The action control point also has a master gatekeeper that receives the address inquiry and generates an address reply, including the terminal address, based on the association in said customer database. 
     In this way, the action control point master gatekeeper acts as the glue between zone gatekeepers. A zone gatekeeper will query to the action control point master gatekeeper for address resolution. The action control point can include a centralized database that associates a terminal alias with a terminal address. The master gatekeeper receives the query, with a terminal alias that needs address resolution, from the zone gatekeeper and looks up the terminal address corresponding to the terminal alias. The terminal address is then returned to the zone gatekeeper. If desired, a zone gatekeeper can maintain a local database for the terminals in that zone. In this case, the zone gatekeeper only queries the master gatekeeper when the address is outside of that zone. 
     In another embodiment of the present invention, the action control point provides a communications service feature based on a requesting terminal identifier in the address inquiry. Such a communications service feature can be provided with the use of, for example, a Network Control Point (NCP). 
     In this way, the action control point master gatekeeper acts as the glue between a zone gatekeeper and specialized processes, such as NCPs. One example of such an NCP would be for authorization codes. The zone gatekeeper sends an address resolution request to the master gatekeeper. The master gatekeeper realizes that the request needs special processing using a table entry in the master database. The master gatekeeper contacts a NCP process, such as an authorization code NCP process, which in turn requests an authorization code from the end user and verifies the code. The NCP process, such as an authorization code NCP process, returns control to the master gatekeeper, which completes the address resolution by sending a reply to the zone gatekeeper. 
     In another embodiment of the invention, a master gatekeeper queries another master gatekeeper to resolve an address. An action control point master gatekeeper can be configured with an arbitrary number of zone gatekeepers into an “administrative domain.” A master gatekeeper from one administrative domain can query a higher level master gatekeeper. The higher level administrative domain master gatekeeper queries the master gatekeeper within a second administrative domain. In this way, a hierarchical network of master gatekeepers can be created to allow for scalable networks. A zone gatekeeper makes an address resolution request to a master gatekeeper, which makes a second request to a higher level master gatekeeper. The higher level master gatekeeper can make a third request to another lower level master gatekeeper, which can either access a master database or query the terminating zone gatekeeper. There can be as many levels of master gatekeepers as required by the size of the network. 
     In still another embodiment, a backup master gatekeeper can be present in the action control point in addition to the normally used, or “primary,” master gatekeeper. A similar backup gatekeeper can be used in a typical H.323 zone. This can be done, for example, by having an action control point master gatekeeper act as a backup zone gatekeeper. Redundant gatekeeper processes can pass queries back and forth so they remain synchronized with the current state of the network at all times. 
     With these and other advantages and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several drawings attached herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a communications zone according to known H.323 procedures. 
     FIG. 2 is a communications network, including an action control point, according to an embodiment of the present invention. 
     FIG. 3 is a communications network, including several administrative domains, according to an embodiment of the present invention. 
     FIG. 4 is a block flow diagram of a method used with an action control point according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention is directed to an action control point master gatekeeper. Referring now in detail to the drawings wherein like parts are designated by like reference numerals throughout, there is illustrated in FIG. 2 a communications network, including an action control point  300 , according to an embodiment of the present invention. 
     The communications network includes two H.323 zones  100 ,  200 . As explained with respect to FIG. 1, each zone  100 ,  200  can include terminals (T), gateways (GW) and gatekeepers (GK), as well as other H.323 entities. Terminals in each zone communicate, such as by IP telephony, with other terminals in that zone. A gateway can let a terminal communicate with other zones and the PSTN. Each zone has a gatekeeper that provides address translation for calls originating in that zone. 
     According to an embodiment of the present invention, the gatekeeper in each zone also communicates with an action control point  300 , which includes a master gatekeeper  310  and a customer database  320 . When a terminal in one zone  100  wants to communicate with a terminal in a different zone  200 , the gatekeeper in the first zone  100  sends an address inquiry, including the terminal alias of the “called” terminal, to the master gatekeeper  310 . The customer database associates a terminal address with one or more terminal aliases for each terminal in each zone served by the action control point  300 . When the master gatekeeper  310  receives the address inquiry, it uses the customer database  320  to determine the terminal address associated with the terminal alias. In place of a local customer database, a master gatekeeper could instead send an address inquiry, including the terminal alias of the “called” terminal, to the zone gatekeeper of the called zone. The zone gatekeeper of the called zone would resolve the address and the master gatekeeper would forward the information to the calling zone gatekeeper. As will be explained with respect to FIG. 3, a master gatekeeper could also send the address inquiry to another master gatekeeper in a different administrative domain. The second master gatekeeper would access its own customer database, or query a zone gatekeeper in the called zone, to resolve the address. 
     Once the terminal address has been determined, the master gatekeeper  3   1   0  sends an address reply, including the terminal address, back to the zone gatekeeper of the calling terminal. The communication can then be established between the terminal in zone  100  and the terminal in zone  200  using normal H.323 signaling. By way of example, an action control master gatekeeper can support a number of zones within an administrative domain. 
     Thus, the master gatekeeper  310  in the action control point  300  provides the signaling infrastructure to extend H.323, which currently does not scale to support carrier requirements, into scalable, reliable carrier class infrastructures. In the circuit switching infrastructure, Signaling System Number 7 (SS7) provides the intelligent signaling infrastructure for advanced services. The action control point  300 , including the master gatekeeper  310 , provides the signaling infrastructure for scalable, reliable and flexible IP network services in an analogous manner. Gatekeepers communicate with each other in an unspecified manner in the H.323 standard, and the present invention imposes a hierarchical signaling infrastructure between gatekeepers, gateways and terminals. Each terminal and gateway will have a primary gatekeeper within a zone. Communications between gatekeepers in different zones will occur using the action control point  300 , including the master gatekeeper  310 , which maintains a distributed database for use by all zone gatekeepers. Communication between administrative domains occurs using a hierarchical signaling between master gatekeepers. 
     The master gatekeeper  310  can include a communications port configured to exchange information with a zone gatekeeper and a processor configured to provide address translation between an alias address and a transport address. An alias address could be, for example, an e-mail name or a telephone number. A transport address could be, for example, an IP address. The customer database  320  maps these addresses, and zone gatekeepers can query the master gatekeeper  310  for address translation. Table 1 shows a sample entry in the customer database  320 . 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Sample Customer database Entry 
               
             
          
           
               
                   
                 Alias Address 
                 Transport Address 
                 Attribute 
               
               
                   
                   
               
               
                   
                 Mike Jones 
                 135.16.34.11 
                 Name 
               
               
                   
                 MBJ@attmail.com 
                 135.16.34.11 
                 e-mail 
               
               
                   
                 www.mbj.com 
                 135.16.34.11 
                 URL 
               
               
                   
                 908-555-2262 
                 135.16.34.11 
                 Telephone 
               
               
                   
                   
               
             
          
         
       
     
     A terminal can setup a call to the “Mike Jones” terminal, or endpoint, using any alias  15 address. The zone gatekeeper for the originating terminal would query the master gatekeeper  310  to identify the transport address, and the master gatekeeper  310  would return the transport address to the zone gatekeeper. The zone gatekeeper could then complete the call setup normally. 
     An embodiment of the present invention also lets an IP network carrier provide communications service features, such as “admission control.” The rules defining the admission control can be stored as attributes in the customer database  320  or in a separate communications service features database (not shown in FIG.  2 ). This will let a carrier introduce IP Private Branch Exchange (PBX) features, such as network services. These carrier-based services are referred to as “IP Centrex.” Another example would be for a carrier to provide “virtual” network services, such as a Software Defined Network (SDN). The current standards for H.323 do not provide the feature functionality customers expect for IP telephony, so an embodiment of the present invention extends H.323 standards to support, for example, a Software Defined Business IP Network (SDBIN). It is likely, for example, that customers will expect the same features currently offered, such as traditional PBX features, to be present on IP phones. Because the action control point  300  provides a single point to store communications service feature attributes, a carrier can provide new services in a rapid and efficient manner to a large number of users. 
     Table 2 shows an action control point  300  database with one simple attribute, “on/off network.” For endpoints in a virtual private network, the on/off network attribute indicates if the originating terminal can call “off-network” to someone on the Internet, or another virtual private network. The on/off network attribute can also indicate if an authorization code is required for the call. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Sample Database Attribute 
               
             
          
           
               
                 Source Address 
                 Transport Address 
                 On/Off Network Attribute 
               
               
                   
               
               
                 908-555-2262 
                 135.16.34.11 
                 Yes 
               
               
                 908-555-5386 
                 135.16.34.12 
                 No 
               
               
                 908-555-3300 
                 135.16.34.13 
                 SDBIN NCP 
               
               
                 908-555-8039 
                 135.16.34.14 
                 Consumer NCP 
               
               
                   
               
             
          
         
       
     
     Assume the four source addresses in Table 2 are part of a virtual private network managed by zone  100  in FIG.  2 . Source address 908-555-2262 can call terminals both on and off the virtual network. Source address 908-555-5386 can only call other locations in the virtual private network, i.e. “on” network calls only. Source address 908-555-3300 requires that the action control point  300  request special processing from a service specific NCP. For example, a SDBIN NCP  420  might prompt source address 908-555-3300 for an authorization code, and the SDBIN NCP  420  could authenticate the authorization code. An IP Centrex NCP  410  could provide “classic PBX features” like hold, transfer, conference and drop calls. Other features that could be offered according to the present invention include: numbering plans; flexible routing; to sub-network partitioning; location screening; feature screening; and credit card authentication. 
     For a consumer application, the action control point  300  can request that a consumer NCP  430  authenticate an authorization code, such as a credit card. For the corporate customer, the authorization code could be the same authorization code used for a circuit switched virtual private network. Different NCPs can implement different features. One interface to a traditional 2NCP  450  would be through the use of Transaction Capabilities Part (TCAP) queries. Consumer NCPs can provide conventional telecommunication Custom Local Area Signal Service (CLASS) features such as call waiting, and call forwarding. Moreover, customized billing options, such as calling cards, can be implemented. 
     Thus, the present invention can easily provide communications service features to H.323 terminals. Carriers require service delivery platforms that facilitate rapid service introduction, such as, for example, an IP voice mail NCP  440 . The zone gatekeeper would establish the call using the action control point  300  as described above. If there is no answer, the zone gatekeeper can ask the master gatekeeper  310  for instructions. The master gatekeeper  310  would call the IP voice mail NCP  440  to provide a voice mailbox. This could be done, for example, using a well accepted Application Programming Interface (API), such as a Telephone API (TAPI), from the master gatekeeper  310  to servers that implement the desired functionality. 
     To make the action control point  300  more reliable, a backup master gatekeeper  330  can be provided according to an embodiment of the present invention. The backup master gatekeeper  330  is a “hot backup” in that it is maintained in a state identical to the state of the primary master gatekeeper  310 . The backup master gatekeeper  330  will take over the action control point  300  when the primary master gatekeeper  310  becomes unavailable, such as when the primary master gatekeeper  310  becomes not operational. In this way, the backup master gatekeeper  330  provides redundant functionality for reliability purposes. Such an implementation can also be used to provide redundant functionality within a typical H.323 zone. This could be done, for example, by having a master gatekeeper act as a backup zone gatekeeper for one or more zones. 
     In addition to providing a signaling infrastructure for communications service features, an embodiment of the present invention provides a network of action control points that can scale. For extremely large networks, a hierarchy of administrative domains can be implemented. FIG. 3 shows such a communications network, including several administrative domains with their associated master gatekeepers  550 ,  560 ,  570 . As shown in FIG. 3, a US master gatekeeper  550  and associated database  555  supports two zones  510 ,  520  in the United States, forming one administrative domain. Although two zones  510 ,  520  are shown in FIG. 3, it will be understood that any number of zones may exist. A Europe master gatekeeper  560  and associated database  565  also supports two zones  530 ,  540  in Europe, resulting in another administrative domain. If desired, the US master gatekeeper  550  can directly query the Europe master gatekeeper  560  for address translation when required. 
     Alternately, a third level administrative domain, such as a global master gatekeeper  570  and associated database  575  could integrate the other administrative domains in the network. Consider, for example, a call placed from a terminal in the United States to a terminal in Europe. A zone gatekeeper in the United States would first query the US master gatekeeper  550 . The US master gatekeeper  550  would query the global master gatekeeper  570 , which would in turn query the Europe master gatekeeper  560 . The distribution of the databases between the various master gatekeepers  550 ,  560 ,  570 , and the various zone gatekeepers, is merely an implementation consideration. 
     FIG. 4 is a block flow diagram of a method used with an action control point according to an embodiment of the present invention. After beginning at step  600 , a master gatekeeper, such as the one shown in FIG. 2, receives an address inquiry, including a terminal alias and a source or requesting terminal identifier, from a zone gatekeeper at step  610 . If the information is not present in the local database at step  620 , another action control point could be queried at step  630 . If the information is present in the local database at step  620 , the database is accessed to determine the terminal address associated with the terminal alias at step  640 . 
     The database can also indicate if a communications service feature should be provided based on the requesting terminal identifier at step  650 . If a service is to be provided at step  660 , an NCP can be accessed to provide the service at step  680 . Finally, an address reply, including the terminal address, can be sent back to the zone gatekeeper at step  670  before the process ends at step  690 . 
     Although various embodiments are specifically illustrated and described herein, it will be appreciated that modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention. For example, although particular communications service features were used to describe the present invention, it will be understood that other features will also fall within the scope of the invention.