Abstract:
A method and network node for supporting a synchronization of a connectivity session location function (CLF) in a communication network. The method uses a processor for sending and receiving messages from a communication network, detecting the unavailability of the CLF, detecting that access information related to the session of the UE is missing from the CLF, receiving missing access information for a session of a UE and synchronizing the CLF on a per session basis. Furthermore, the processor accesses a memory for storing access information and synchronizes the stored access information of the session with the received missing access information of the session of the UE stored during unavailability of the CLF.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to communication systems and methods and, more particularly, to mechanisms and techniques for updating the content of a network entity. 
       BACKGROUND 
       [0002]    Communication systems continue to grow and evolve. Convergence between different types of communication systems, e.g., Internet Protocol (IP), connection-based voice communications, and the like, is advancing rapidly. Recently the phrase “Next Generation Network” (NGN) has been used to describe various activities associated with this evolution. As defined by the International Telecommunications Union (ITU), an NGN is a packet-based network able to provide services (including telecommunication services) and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. NGNs will also likely offer unrestricted access by users to different service providers and will support generalized mobility, which in turn will provide for consistent service provision to end users. 
         [0003]    Various standardization groups are working on reaching a consensus regarding the technology considerations which will affect NGN design and implementation. For example, Telecoms &amp; Internet converged Services &amp; Protocols for Advanced Networks (TISPAN) is an ETSI standardization group which focuses on convergence of technologies used in the Internet and other fixed networks. Among other things, TISPAN seeks to provide a modular, subsystem-oriented architecture which facilitates the addition of new subsystems over time to cover new demands and service classes. The TISPAN architecture attempts to ensure that network resources, applications, and user equipment are common to all of the various subsystems to provide for enhanced mobility across, for example, administrative boundaries. 
         [0004]    One of the TISPAN subsystems is referred to as the Network Attachment Sub System (NASS). The NASS is responsible for, among other things, handling configuration information, user authentication data, IP address allocation and registering associations between IP addresses allocated to user equipment (UE) and related network location information. These latter two NASS functions, i.e., allocating IP addresses and registering associations, are handled by the Network Access Configuration Function (NACF) and the Connectivity Session Location and Repository Function (CLF), respectively, which are functional entities that are also specified by the NASS portion of the TISPAN standards. 
         [0005]    These NASS functional entities interact with another TISPAN subsystem known as the Resource Admission Control Subsystem (RACS) and the Access Resource and Admission Control Function (A-RACF) functional entity of the RACS. The A-RACF functional entity, among other things, receives information about the IP address allocated to a particular user and maps that IP allocation to physical resources in the access network. Each A-RACF is, in these exemplary embodiments, associated with a Session Border Controller (SBC). An SBC interacts directly with the network elements that provide communication services to an end user, e.g., Digital Subscriber Line Access Multiplexers (DSLAMs). 
         [0006]    In the TISPAN network model, the NACF-CLF interface, which is defined as an a2 interface, identifies a set of primitive used to accomplish the tasks associated with the exchange of information between the two nodes. The a2 interface supports the Bind Indication, Bind Acknowledgment and Unbind Indication. These primitives are used to send the binding information between the IP Address and network specific data. This data can be used to lookup the data in the CLF and associate the binding to location information for instance. However, the interface only provides a PUSH interface where the information is meant to flow only from the NACF to the CLF. In this case, the CLF cannot synchronize its data efficiently since it would require sending the entire NACF database over the a2 as a possible synchronization alternative because the interface does not include the necessary primitives to perform that function. 
         [0007]    One problem associated with these primitives is that these primitives are push only and does not take into account re-synchronizations needs, which are required in any system with HA requirements. These synchronization scenarios are quite complex and it becomes apparent that a push only interface will not solve all the problems, because the CLF does not know when the data has changed on the NACF resulting in a PULL for each request. A PULL only interface does not solve all problems as it lacks the ability for the NACF to notify the CLF of changes that is occurring at that time. 
         [0008]    Accordingly, it would be desirable to have a mechanism for allowing the CLF to synchronize its data with the NACF after unavailability of the CLF. 
       SUMMARY 
       [0009]    It is a broad aspect of the present invention to provide a method for supporting a synchronization of a connectivity session location function (CLF) in a communication network, the method comprising steps of: 
         [0010]    detecting the unavailability of the CLF; 
         [0011]    storing access information related to a session of a user equipment (UE), at a network access configuration function (NACF), during the unavailability of the CLF; 
         [0012]    recovering network node capabilities at the CLF; 
         [0013]    receiving from a network node a request for retrieving access information for the session of the UE; 
         [0014]    detecting that access information related to the session of the UE is missing from the CLF; 
         [0015]    sending an access information request to the NACF for retrieving the missing access information for the session of the UE; 
         [0016]    receiving an acknowledgement message from the NACF, the acknowledgment message including the missing access information for the session of the UE; and 
         [0017]    synchronizing the CLF for the session of the UE. 
         [0018]    It is another broad aspect of the present invention to provide a network node for synchronizing access information between a network node and a communication network following an unavailability of the network node, the network node comprising: 
         [0019]    a processor for sending and receiving messages from a communication network, detecting the unavailability of a connectivity session location function (CLF), detecting that access information related to the session of the UE is missing from the CLF, receiving missing access information for a session of a user equipment (UE) and synchronizing the CLF for the session of the UE; and 
         [0020]    wherein the processor accesses a memory for storing access information and synchronizes the stored access information for the session with the received missing access information stored during unavailability of the CLF. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The foregoing and other aspects, features, and advantages of the invention will be apparent from the following more particular detailed description as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
           [0022]      FIG. 1  is a schematic diagram illustrating a communication network for providing Internet Protocol (IP) services to a user equipment (UE) in accordance to the invention; 
           [0023]      FIG. 2  is a schematic diagram illustrating a network node for managing access information for UEs and queries made from other network node in the communication network, in accordance to the invention; 
           [0024]      FIG. 3  illustrates the steps of a method for synchronizing a CLF after unavailability of the CLF, in accordance to the invention; and 
           [0025]      FIG. 4  is an example of a list of parameters related to access information stored at a CLF and to be updated for a UE, in accordance to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques. In order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail. 
         [0027]    In order to provide some context within which exemplary embodiments will be better understood, consider the exemplary portion of a communication network  100  illustrated as  FIG. 1 . It will be appreciated by those skilled in the art that this example is purely illustrative and that exemplary embodiments may be implemented in many types of networks other than the example provided as  FIG. 1 . Therein, the portion of the communication network associated with a network plane  102  and the user plane  104  is illustrated. Other network planes (not shown) may also be supported in, e.g., their resource allocation functions, by the CLF  22  and NACF  24 . The CLF  22  and NACF are described as standalone network node, but they can alternatively be combined and in a single network node. 
         [0028]    To briefly step through the exemplary network structure illustrated in  FIG. 1 , a number of consumer premise equipments (CPEs)  26 , sometimes also referred to as “user equipments (UEs)”, are connected to the network through a digital subscriber line access multiplexer (DSLAM)  28 . The DSLAMs  28  multiplex signals from the CPEs  26  together and load them onto the network via an edge collect router (ECR)  30 . Communications between the end user and the network  100  are passed between the ECR  30  and a session border controller (SBC)  32 . The SBC  32  operates as a gateway device between the end user (CPE  26 ) and the network  100  and can transmit and receive messages including information associated with a location information query for, e.g., 911 purposes. The NACF  24  is a DHCP server from which the ECR  30  requests an IP address, via a DHCP request along with Option  82  parameters, for the associated CPE  26  which has attached to the network. This IP address is allocated from a subnet pool configured in the NACF  24 . Once the IP address is allocated and returned to the ECR  30 , then NACF  24  can then push this Network Attach information along with the location of the associated CPE  26  to the CLF  22 , which acts as a session data repository for CPEs  26 . A session establishes an association, which is performed for example by the CLF  22 , between an IP address allocated to the CPE and other information e.g. network location information. The SBC  32  interfaces with the rest of, for example, an IP backbone network (not shown) to, for example, interconnect a CPE  26  with another device, website, etc. 
         [0029]    The implementation of a push/pull interface or the like according to these exemplary embodiments can impact, among other things, the CLF  22  and NACF  24  entities within the communication network  100 . Structurally, the CLF  22  and NACF  24  can, for example, each be implemented in hardware and software as servers. For example, as shown generally in  FIG. 2 , such a server  200  can include a processor  202  (or multiple processor cores), memory  204 , an operating system  208  running on the processor  204  and using the memory  204 , as well as a corresponding application  210 , e.g., a CLF application for the CLF server and an NACF application for the NACF server. An interface unit  212  may be provided to facilitate communications between the network node  200  and the rest of the network  100  (interface e 4 ) or between the CLF  22  and the NACF  24  (interface a 2 ). The interface unit  212  may also be integrated into the processor  202 . Thus, a network node  200  according to an exemplary embodiment may include a processor  202  for transmitting and receiving messages associated with at least one of location of user equipment and IP address allocation to a user equipment (CPE). 
         [0030]    While  FIG. 2  is generic to, for example, a CLF network node or a NACF network node, the specific messages which are transmitted and received according to these exemplary embodiments will vary by, for example, the type of node under consideration. For example, a CLF network node  200  can operate to register an association between an IP address allocated to the user equipment and network location information and can, therefore, transmit messages to the network over an a2 interface and receive messages from the network  100  over an e4 interface. The messages may include information associated with at least one of: initial gate setting, list of allowed destinations, uplink subscribed bandwidth, downlink subscribed bandwidth, QoS profile information, transport service class, media type, maximum priority and requestor name, among other things. 
         [0031]    Similarly, an NACF network node  200  operates to verify that bandwidth needed for services requested by particular IP address allocation to a particular CPE  26 . The NACF  24  may also distribute other network configuration parameters. The NACF  24  can transmit messages to the network over an a2 interface and receive messages from the network  100  over an e4 interface. The messages may include information associated with at least one of: initial gate setting, list of allowed destinations, uplink subscribed bandwidth, downlink subscribed bandwidth, QoS profile information, transport service class, media type, maximum priority and requestor name. 
         [0032]    Reference is now made to  FIG. 3 , which illustrates the steps of a method for re-synchronizing a CLF  22  after failure because of an outage, an overload of the processing or after maintenance of the CLF  22 , in accordance to an exemplary embodiment of the invention. Reference is also made to  FIG. 4 , which is a list of CPEs  26  connected to DSLAM  28  associated to the portion of the network  100  as illustrated in  FIG. 1 . 
         [0033]    At step  300 , the CLF  22  receives access information  302  for a session of a CPE  26  consisting of, while not being limited to these parameters, the IP address  404  of the CPE  26 , Logical Access identifier (ID)  408 , CPE ID  402  and other parameters present in Option  82  parameters such as the Physical location  406  of the CPE  26 . Upon reception of the access information  302  for a CPE  26 , the CLF  22  stores in the list  400  this access information or updates the list  400 . The CLF  22  may become unavailable due to failure or for maintenance operations of the CLF  22  (step  304 ). When such unavailability of the CLF  22  is detected at the CLF (processor  202 ) or at the NACF (step  308 ), the NACF  24  stores all messages related to the new access information  315  for the session of the CPE  26 , which is to be sent to the unavailable CLF  22  (step  312 ). More particularly, during the synchronous mode (availability of the CLF  22 ), the NACF  24  assigns an IP address to each CPE  26 . When there is no response from the CLF  22 , the Network Attachment can be successful but the new binding information (access information  315 ) is not pushed to the CLF  22 . Alternatively, during the asynchronous mode (unavailability of the CLF  22 ), the Network Attachment can be done between the NACF  24  and the CPE  26 , resulting in the corresponding new access information  315  missing in the CLF  22  for a session of a CPE  26 . The session may be a Session Initiation Protocol (SIP) session or any IP session that requires access information to be sent to a requesting network node. 
         [0034]    The IP address in the CPE  26  and the NACF  24  can be released without notifying the CLF  22 . A data recovery of missing access information  315  due to unavailability of the CLF  22  may be performed by a data synchronization by the NACF  24 . As previously mentioned, the NACF  24  is the master database of the IP address allocation, which stores the accurate access information of the session when an IP address is reserved or released. However, when the NACF  24  tries to push some messages to the CLF  22  in order to update the access information  302  with the new access information  315  for the session and when there is no response from the CLF  22  because a failure or a maintenance operation occurs at the CLF  22 , the NACF  24  stores the undelivered messages (access information  315 ) and resent them when the CLF  22  recovers. The sending of the messages directed to the CLF  22  is based on the steps performed after the recovery of the CLF  22 . 
         [0035]    After a certain amount of time, which may vary depending on the importance of the failure or the maintenance operations of the CLF  22 , the CLF  22  may recover its network node capabilities for allowing it to perform normal operation as before the unavailability (step  316 ). A network node, for example a SBC  32 , may request location information regarding a session for particular a CPE  26  (request  321 , step  320 ), the CLF  22  then detects that it needs a synchronization of the content of its list  400  (step  324 ). Thus, the CLF  22  is synchronized only when needed for a particular session and does not need to reload the whole content of the NACF  24 . 
         [0036]    In particular, the recovery data which corresponds to the access information  315  stored in the NACF  24  during unavailability of the CLF  22  may be retrieved by the SBC  32 . When the SBC  32  queries the CLF  22 , e.g. for the new location information missing during the failure period of the CLF node  22  the CLF is triggered, while not being limited to, when a request  106  is received at the SBC  32  the CPE  26 . Such request  106  sent to the SBC  32  or another network node is, for example, on a request  106  for services or a session initiation request, while not being limited to such request, from the particular CPE  26 . 
         [0037]    Thus, in order to recover the access information  315  for the session, the CLF  22  sends a request  325  to the NACF  24  (step  328 ). The request  325  may, for example, while not being limited to, contain the information of table 1 (Bind request). 
         [0000]    The Bind Indication information flow contains the following information. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Bind Indication (CLF -&gt; NACF) 
               
             
          
           
               
                   
                 Globally Unique Address 
                   
               
               
                   
                   
               
               
                   
                 Assigned IP Address 
                 The IP address allocated to the terminal 
               
               
                   
                   
                 equipment. 
               
               
                   
                 Addressing Realm 
                 The addressing domain in which the IP 
               
               
                   
                   
                 address is significant. 
               
               
                   
                   
               
             
          
         
       
     
         [0038]    The NACF  24  processes this request and sends an acknowledgment response  329  to the CLF  22 . The acknowledgement response  329  includes the access information  315  for the session of the CPE  26 , which is stored at the NACF  24  during the unavailability of the CLF  22 . The acknowledgement response  329  may, for example, while not being limited to, contain the information of table 2 (Bind Request Acknowledgment). 
         [0000]    The Bind Request Acknowledgment information flow contains the following information. 
         [0000]    
       
         
               
             
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Bind Request Acknowledgment (NACF -&gt; CLF) 
               
             
          
           
               
                 Globally Unique Address 
                   
               
               
                   
               
               
                 Assigned IP Address 
                 The IP address allocated to the terminal 
               
               
                   
                 equipment. 
               
               
                 Addressing Realm 
                 The addressing domain in which the IP 
               
               
                   
                 address is significant. 
               
               
                 Physical Access ID 
                 The identity of the physical access to 
               
               
                 (optional) 
                 which the user equipment is connected 
               
               
                 Logical Access ID 
                 The identity of the logical access used 
               
               
                   
                 by the attached terminal equipment. 
               
               
                   
                 (NOTE 1) 
               
               
                 Terminal Type 
                 The type of terminal equipment. (NOTE 2) 
               
               
                 (optional) 
               
               
                   
               
               
                 NOTE 1: If the NACF is implemented as a DHCP server, this parameter is mapped to the DHCP option 82, sub-option 1 and 2. 
               
               
                 NOTE 2: If the NACF is implemented as a DHCP server, this parameter is mapped to the DHCP option 77. 
               
             
          
         
       
     
         [0039]    When receiving the access information  315  (step  332 ), the CLF  22  updates and synchronizes the list  400  for the session and for the CPE  26  for which the information is related (step  336 ). The recovery data in the CLF  22  is then consistent with the content (all the pushed messages) stored in the NACF  24  for the session during the period of unavailability of the CLF  22 . The CLF  22  ultimately replies to the request received from the SBC  32  by sending the requested information (location information) for the CPE  26  (step  340 ). Those skilled in the art will appreciate that the same process may be applied to request received from other network node than the SBC  32 . It can be understood that the CLF  22  can store access information related to a session for a plurality of CLF  22  in list  400  and is not only limited to the synchronization process of only one session. However, a session is only synchronized when required at the CLF and based on a request received on such session from a network node in the communication node  100 . 
         [0040]    While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations may be made therein without departing from the spirit and scope of the invention.