Abstract:
A novel method and apparatus is presented for providing transparent mobility of an entity within a network, by allowing the entity, which has a communication path set up between it and a peer entity, to move from one location to another, without informing the peer entity of this movement, and without having the communication path broken. The invention is applicable to decentralized networks using IP protocols, and is particularly applicable on networks where the mobility mechanism neither introduces latency nor decreases the available bandwidth of the network. In the invention, neither is latency increased nor is bandwidth utilization increased, as is done in other mobility models. Additionally, the invention utilizes standard protocols that are widely available from a plurality of equipment manufacturers on a variety of platforms. Thus, the invention provides a very cost-effective model for network providers that need to support transparent mobility within their networks.

Description:
CROSS REFERENCE OF APPLICATION  
       [0001]    This application claims priority from U.S. application Ser. No. 09/451,400, filed Nov. 30, 1999, entitled “Method and Apparatus for Providing Mobility Within a Network” which claims priority from Provisional Application Serial No. 60/163,325, filed Nov. 3, 1999, both currently assigned to the assignee of the present application. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    I. Field of the Invention  
           [0003]    The current invention relates to mobility within a telecommunications system. More particularly, the present invention relates to a method and apparatus for transparently relocating an anchor point within the serving network of a wireless telecommunications system from one location to another.  
           [0004]    II. Description of the Related Art  
           [0005]    The use of a decentralized serving network for use in a wireless telecommunications system is disclosed in U.S. Pat. No. 6,215,779, entitled “DISTRIBUTED INFRASTRUCTURE FOR WIRELESS DATA COMMUNICATIONS”, applied for by the applicant of the present invention, and incorporated by reference herein. The above application discusses a telecommunications decentralized serving network in which, rather than there being a single point of control, there are multiple control points distributed throughout the serving network of the telecommunications system.  
           [0006]    The Internet Engineering Task Force (IETF) is the standards body that creates the majority of standards related to the Internet Protocol (IP). Many of the standards created by the IETF are called RFCs. RFC is shorthand for ‘Request For Comments.’ 
           [0007]    Open Shortest Path First (OSPF) was standardized by the IETF to address, in part, the routing of packets in a network in which one or more of the routers experiences a failure, thus enhancing the reliability of a network. OSPF was designed in such a way that, of all the routers which are working at any given moment, the shortest path is taken from node A to node B. Additionally, OSPF was designed such that, if multiple equivalent routes exist from node A to node B, any one of the equivalent routes can be selected. With OSPF in place, a network with redundant routes can perform load balancing on the routers. OSPF is available on many makes and models of routers, and is described in IETF RFC 2328, incorporated by reference herein.  
           [0008]    Mobile IP is present in many IETF standards to make it possible for a device, containing an IP address, to travel through a network (or networks). The standard, RFC 2002, ‘IP Mobility Support,’ incorporated by reference herein, addresses the problem of IP Mobility, and uses a solution termed ‘Mobile IP.’ Several other Mobile IP related standards also exist, such as RFCs 2006, 2041, 2290, 2344, and 2356, each of which is incorporated by reference herein. Local Area Network (LAN) system administrators that want to support mobility are guided by the IETF standards to use Mobile IP. Mobile IP provides support not only for mobility within a LAN, but also for mobility within a Wide Area Network (WAN).  
           [0009]    In a decentralized telecommunications network, the service devices chosen are widely available off-the-shelf units that use open standards for their interfaces rather than proprietary protocols that are limited to a single supplier. Many, if not all, of the service devices are designed to communicate with a single anchor point for each active session. Meaning, such off-the-shelf devices, and the protocols they incorporate, are not designed to begin a session with one device and ends the same session with a different device. This restriction can lead to non-optimized routing for individual sessions. Such non-optimized routing situations are illustrated in FIG. 8A and FIG. 8B. What is needed is a method by which a service device&#39;s anchor point for an active session can be relocated without the need for specific anchor point relocation support in the service device. Specifically, such a method should be very efficient and robust, minimizing latency and bandwidth usage.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention is a novel method and apparatus for providing transparent mobility of an entity within a serving network of a wireless telecommunications system. The invention provides for the transparent mobility of a data anchor point within a network, allowing the anchor point to move from one physical location of the network to another physical location of the network. The type of mobility is termed ‘transparent’ because the peer entity communicating with the anchor point doesn&#39;t receive a message indicating that the anchor point has moved, nor is the peer entity required to perform any special functions to remain in communication with an anchor point that has moved from one location to another. In other words, the peer entity communicating with the data anchor point performs no differently in a session in which the anchor point remains fixed than it does in a session in which the anchor point changes physical locations.  
           [0011]    The present invention is applicable to decentralized networks in which transparent mobility is desired. The present invention is particularly applicable on networks wherein it is desired that the mobility mechanism neither introduces latency nor decreases the available bandwidth of the network. Such networks include, but are not limited to, a CDMA wireless data network and a GSM wireless data network.  
           [0012]    All embodiments of the present invention are novel methods and apparatus for handling mobility within a serving network of a wireless telecommunications system. The exemplary embodiment of the present invention has broader applicability, in that it provides a novel method for handling mobility in all types of networks, including corporate and government networks. Other mobility models can require a centralized network to manage anchor point mobility. Additionally, other mobility models can use of a significant amount of available bandwidth and can significantly increase latency. The present invention neither has deleterious latency nor bandwidth effects. Additionally, the present invention utilizes standard protocols that are widely available from a plurality of equipment manufacturers on a variety of platforms. Thus, the present invention provides a very cost-effective model for network providers that desire to support transparent mobility within their network.  
           [0013]    The exemplary embodiment of the present invention uses OSPF to achieve transparent anchor point mobility. Mobile IP is used in an alternative embodiment of the present invention to provide transparent anchor point mobility in the serving network of a wireless telecommunications system. OSPF is used in the exemplary embodiment of the present invention because the use of OSPF does not introduce the tunneling overhead that is introduced in Mobile IP, and OSPF does not introduce the latency that can be caused by the indirect routing common in Mobile IP. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:  
         [0015]    [0015]FIG. 1 is a block diagram of exemplary embodiment of an Access Terminal in communications with a Wireless Telecommunications Decentralized Serving Network.;  
         [0016]    [0016]FIG. 2 is a functional block diagram of an exemplary embodiment of a decentralized serving network of a wireless telecommunications system;  
         [0017]    [0017]FIG. 3 is a functional block diagram of an exemplary embodiment of an access point;  
         [0018]    [0018]FIG. 4 is a functional block diagram of an exemplary embodiment of a modem pool controller;  
         [0019]    [0019]FIG. 5 is a functional block diagram of an exemplary embodiment of a modem pool transceiver;  
         [0020]    [0020]FIG. 6A is a network diagram of an exemplary embodiment of the data path from an access terminal to the internet, wherein the access terminal is in communication with a first modem pool transceiver of a serving network of a wireless telecommunications system;  
         [0021]    [0021]FIG. 6B is a block diagram of the data path taken in relation to FIG. 6A;  
         [0022]    [0022]FIG. 7A is a network diagram of an exemplary embodiment of the data path from an access terminal to the internet, wherein the access terminal is in soft-handoff with a first and second modem pool transceiver of a serving network of a wireless telecommunications system;  
         [0023]    [0023]FIG. 7B is a block diagram of the data path taken in relation to FIG. 7A;  
         [0024]    [0024]FIG. 8A is a network diagram of an exemplary embodiment of the data path from an access terminal to the internet, wherein the access terminal is in communication with a second modem pool transceiver of a serving network of a wireless telecommunications system, and the anchor point transfer of the present invention has yet to occur;  
         [0025]    [0025]FIG. 8B is a block diagram of the data path taken in relation to FIG. 8A;  
         [0026]    FIGS.  9 A- 9 B are a flowchart illustrating an exemplary embodiment of the anchor point transfer methodology of the present invention.  
         [0027]    [0027]FIG. 10A is a network diagram of an exemplary embodiment of the data path from an access terminal to the internet, wherein the access terminal is in communication with a second modem pool transceiver of a serving network of a wireless telecommunications system, and the anchor point transfer methodology of the present invention has been utilized;  
         [0028]    [0028]FIG. 10B is a block diagram of the data path taken in relation to FIG. 10A; and  
         [0029]    [0029]FIG. 11 is a functional block diagram of a preferred embodiment of a decentralized serving network of a wireless telecommunications system. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0030]    [0030]FIG. 1 is a block diagram of exemplary embodiment of an Access Terminal in communications with a Wireless Telecommunications Decentralized Serving Network. Access terminal  110  is a wireless terminal that can be used to access one or more of a plurality of services, including Public Switched Telephone Network (PSTN) and Internet services, offered by the serving network of a wireless telecommunications system  120 . Wireless telecommunications system  120 , and PSTN  122  and Internet  124  to which wireless telecommunications system  120  connects, are further described in reference to FIG. 2. In the exemplary embodiment, access terminal  110  is able to connect to the serving network of a wireless telecommunications system via the use of a radio antenna. Access terminal  110  can maintain a communication link with the serving network of a wireless telecommunications system by communicating with one or more access points, further described in reference to FIG. 2 and FIG. 3.  
         [0031]    [0031]FIG. 2 is a functional block diagram of an exemplary embodiment of a decentralized serving network of a wireless telecommunications system, hereinafter also referred to as network  120 . Access terminal  110  can communicate with network  120  over a wireless link.  
         [0032]    Network  120  is comprised of a plurality of access points  220 , which can communicate with access points  110 , and are further described in reference to FIG. 3. Additionally, network  120  is further comprised of one or more router(s)  260 , which connect access points  220  to service devices  270 . Service Devices  270  are connected to PSTN  122  and Internet  124 . Although network  120  connects to external entities PSTN  122  and Internet  124  in FIG. 2, the invention is not limited to a network which connects to these entities. One skilled in the art would know that other entities, such as a private external information provider, or a billing service entity, could be connected to network  120  as well. Additionally, it is not required that either PSTN  122  or Internet  124  be connected to network  120 . PSTN  122  and Internet  124  were put in FIG. 2, to give an illustration of the type of entities to which network  120  could be connected.  
         [0033]    PSTN  122  represents the Public Switched Telephone Network, the aggregate of all of the circuit switched voice networks throughout the world. The term PSTN is well known to those experienced in the field of telecommunications.  
         [0034]    Internet  124  represents the public Internet, a network of computers that spans the world and is used by individuals, governments, corporations, and organizations to share information amongst computers and computing devices. The term Internet is well know to those experience in the field of telecommunications.  
         [0035]    H323 Gateway  271  provides H.323 services in accordance with the H.323 standard, thus providing standardized multimedia communications over a network. The H.323 standard was developed by the International Telecommunications Union, and is described in ITU-T Recommendation H.323. H.323 Gateway is connected to PSTN  122  and Internet  124 . One skilled in the art of the related fields would be familiar with the services provided by an H323 Gateway.  
         [0036]    NAS  272  is a Network Access Server. NAS  272  provides packet data services in accordance with the IETF Internet Draft “Network Access Server Requirements Next Generation (NASREQNG) NAS Model.” One skilled in the art of the related fields would be familiar with the services provided by a Network Access Server.  
         [0037]    AAA Server  274  provides Authentication, Authorization, and Accounting services. A RADIUS server is one example of an AAA server, and is described in IETF RFC 2138. One skilled in the art of the related fields would be familiar with the services provided by an AAA server.  
         [0038]    DHCP Server  276  provides dynamic host configuration services in accordance with the Dynamic Host Configuration Protocol, which is described in IETF RFC 2131. One skilled in the art of the related fields would be familiar with the services provided by a DHCP server.  
         [0039]    DNS Server  278  provides Domain Name Services. DNS is described in “Internetworking with TCP/IP Volume I, Principles, Protocols, and Architecture,” by Douglas E. Comer. One skilled in the art of the related fields would be familiar with the services provided by a DNS server.  
         [0040]    All of the above devices are “off-the-shelf” and use standard, non-proprietary protocols.  
         [0041]    Although the illustration of Service Devices  270  contains H323 Gateway  271 , NAS  272 , AAA Server  274 , DHCP Server  276 , and DNS Server  278 , the invention is not limited to a network which contains exactly these service devices. One skilled in the art would know that other services, such as a Web page server, could be one of the service devices in Service Devices  270 . Additionally, it is not required that any or all of the service devices illustrated in Service Devices  270  be present. These chosen devices were illustrated to give an example of the type of entities that could be contained in Service Devices  270 .  
         [0042]    Network  120  connects Access Points  220  and Service Devices  270  together via various Ethernet connections and the use of a router  260 . Router  260  is an off-the-shelf router which routes (forwards) packets received from one physical interface to one or more other interfaces using an internal process to determine to which interface to forward each received packet. Routers are well known to those skilled in the art, and are often referred to by other names, such as gateways or switches. In the exemplary embodiment of the invention, router  260  is an off-the-shelf router which forwards IP (Internet Protocol) packets received from a plurality of Ethernet transports  280  to one or more of said Ethernet transports  280 . In the exemplary embodiment, router  260  supports the OSPF routing protocol. Ethernet is defined in IEEE 802.3, a standard published by the Institute of Electrical and Electronic Engineers (IEEE). The OSPF routing protocol is described in IETF RFC 2328. The OSPF routing protocol allows standard messages to be sent between routers to update their routing tables, such that IP packets can be delivered via the data path that has the lowest cost (the term ‘cost’ is described in IETF RFC 2328). The OSPF protocol has an age field that is transmitted in each Link State Advertisement message. The age field indicates to a receiving router how long the Link State Advertisement should remain valid for. A receiving router associates an age with the Link State Advertisement consistent with the age field received in a Link State Advertisement. A receiving router increments the associated ages for its routes as time passes. A receiving router compares these ages with the maximum age. Once an age associated with a route reaches the maximum age, the route is deleted. Hereinafter, the maximum age is referred to as MaxAge, as is per the description in IETF RFC 2328. One skilled in the art of data networks would be familiar with Ethernet, IP, and OSPF.  
         [0043]    Although the illustration of network  120  connects access points  220 , router  260 , and Service Devices  270 , via an IP over Ethernet transport  280 , the invention is not limited to a network with a sole transport mechanism consisting of IP over Ethernet. One skilled in the art of networking is familiar with an ethernet transport  280  that is used to carry IP packets from one point on a network to another. One skilled in the art would know that other transports, such as Asynchronous Transfer Mode (ATM), could be used as a transport over all or a portion of network  120 , in an alternative embodiment. Although, in the exemplary embodiment, network  120  consists of two subnets divided by a single router  260 , an alternative embodiment could consist of two or more routers  260 , connecting two or more subnets.  
         [0044]    [0044]FIG. 3 is a functional block diagram of an exemplary embodiment of an Access Point. Access Point  220  is the portion of network  120  that receives data from a service device  270  and creates capsules and transmits them over a wireless link to an access terminal  110 .  
         [0045]    Access point  220  consists of a single MPC  320 , further described in reference to FIG. 4, and zero or more MPTs  330  connected each of which is connected to an antenna, further described in reference to FIG. 5. In the exemplary embodiment, MPC  320  and MPTs  330  are connected to router  350  via IP over Ethernet transport  340 .  
         [0046]    Although the illustration of Access Point  220  connects MPC  320  and MPTs  330  via an IP over Ethernet transport  340 , the invention is not limited to such a transport. In one alternative embodiment, an ATM transport is used. In another alternative embodiment, MPC  320 , MPTs  330 , and router  350  are located on a single processing unit, and the router receives packets from these logical memory units via memory functions and signaling internal to the processor. One skilled in the art would know that several other transports are available as well.  
         [0047]    [0047]FIG. 4 is a functional block diagram of an exemplary embodiment of a Modem Pool Controller (MPC)  320 . MPC  320  is analogous to a Base Station Controller plus a Visitor Location Register (VLR), known to those skilled in the art of wireless telecommunication. Whereas a Base Station Controller controls certain functions in a centralized serving network of a wireless telecommunications system, MPC  320  performs many of those same functions in the exemplary decentralized network. For example, MPC  320  handles connection control for access terminals  110 , and also handles the implementation of the Radio Link Protocol (RLP). An RLP provides a means for transporting a data stream between a remote station and wireless telecommunications system. As is known to one skilled in the art, an RLP used for the TIA/EIA/IS-95B is described in Radio Link Protocol (RLP) is described in TIA/EIA/IS-707-A.8, entitled “DATA SERVICE OPTIONS FOR SPREAD SPECTRUM SYSTEMS: RADIO LINK PROTOCOL TYPE 2”, incorporated by reference herein. MPC  320  also handles a plurality of processes unique to the decentralized network and the present invention, especially in regards to the present invention. The process of the present invention will be described in great detail in relation to FIGS.  9 A- 9 B.  
         [0048]    For each active Internet data connection associated with a given MPC  320 , MPC  320  generates capsules to be transmitted by one or more MPTs  330 , and ships these capsules to MPT  330 . Likewise, when MPC  320  receives a capsule from one or MPTs  330 , it unencapsulates the payload of the capsule and processes the data. MPC  320  contains one Common Controller (CC)  420  and zero or more dedicated controllers (DCs)  430 . Each dedicated controller  430  functions as an anchor point to the service device(s)  270  to which it is connected.  
         [0049]    Exactly one CC  420  exists for each instance of MPC  320 . As illustrated in FIG. 4, CC  420  is assigned two unique IP addresses, IP CCT  and IP CCO . One of these IP addresses, IP CCT , is used when communicating with MPTs  330 . The other IP address, IP cco , is used when communicating with entities present in network  120  other than MPTs  330 .  
         [0050]    Each time a session between an access terminal  110  and a network  120  starts, CC  420  dynamically allocates resources for a DC  430 . Each DC  430  handles the generation of and the reception of capsules associated with the access terminal with which it is associated. Each time a session between an access terminal  110  and a network  120  ends, CC  420  deletes the instance of DC  430 . Whenever an instance of DC  430  is deleted, the resources previously allocated to that instance are deallocated. As illustrated, a plurality of zero or more DCs  430  can coexist within MPC  320  at any given time.  
         [0051]    Each time CC  420  allocates resources for an instance of DC  430 , the instance of DC  430  is assigned two unique IP addresses, IP DCT  and IP DCO . One of these IP addresses, IP DCT , is used when communicating with MPTs  330 . The other IP address, IP DCO , is used when communicating with entities present in network  120  other than MPTs  330 , such as NAS  272 . In blocks  430 A,  430 B, and  430 N, the characters ‘A’, ‘B’, and ‘N’, respectively, have been added to the subscripts of each of the IP addresses. This was done to illustrate that, in the exemplary embodiment, at any given point in time in which multiple instances of DC  430  exist within MPC  320 , each such instance has its own unique pair of IP addresses.  
         [0052]    CC  420  and DCs  430  send and receive messages over IP transport  440  to Internal Router  450 . In the exemplary embodiment, IP transport  440  is a memory bus over which IP packets can travel from one process to another and to an interface card. Internal Router  450  is a network interface card, which routes IP packets to/from IP transport  440  and external transport  340 . The invention is not limited to this embodiment. As one skilled in the art would know, there are other embodiments, such as Ethernet, which could be used to transport IP packets within MPC  320  and external transport  340 .  
         [0053]    [0053]FIG. 5 is a functional block diagram of an exemplary embodiment of a Modem Pool Transceiver (MPT)  330 . MPT  330  handles the transmitting and receiving of capsules to/from access terminal  110 . In the exemplary embodiment, communications between MPT  330  and access terminal  110  utilize variable rate spread spectrum techniques as described in U.S. patent application Ser. No. 08/963,386 entitled “Method and Apparatus for High Rate Packet Data Transmission” filed on Nov. 3, 1997, assigned to the assignee of the present invention and incorporated by reference herein. MPT  330  contains one common transceiver (CT)  520  and a plurality of zero or more dedicated transceivers (DTs)  530 , each of which is capable of performing the spread spectrum modulation and demodulation used for communications with one or more access terminals.  
         [0054]    In the exemplary embodiment, exactly one CT  520  exists for each instance of MPT  330 . As illustrated in FIG. 5, CT  520  is assigned one unique IP addresses, IP CT , to communicate with entities present in network  120 .  
         [0055]    Each time it is desired to open a dedicated communication link between an access terminal  110  and an MPT  330 , CT  520  dynamically creates an instance of DT  530 . Each DT  530  handles the transmission/reception of capsules associated with the dedicated communication link to an access terminal  110 . Each time it is desired to close a dedicated communication link between an access terminal  110  and an MPT  330 , CT  520  deletes the instance of DT  530 . As illustrated in FIG. 5, a plurality of zero or more DTs  530  can coexist within MPT  330  at any given time.  
         [0056]    Each instance of DT  530  is assigned its own unique IP address IPDT used to communicate with entities present in network  120 . In blocks  530 A,  530 B, and  530 N, the characters ‘A’, ‘B’, and ‘N’, respectively, have been added to the subscripts of each of the IP addresses. This was done to illustrate that, in the exemplary embodiment, at any given point in time in which multiple instances of DT  530  exist within MPT  330 , each such instance has its own unique IP addresses. In other words, the IP addresses assigned to each concurrent instance of MPT  330  are not the same.  
         [0057]    CT  520  and DTs  530  send and receive messages over IP transport  540  to Internal Router  550 . In the exemplary embodiment, IP transport  540  is a memory bus over which IP packets can travel from one process to another and to an interface card. Internal Router  550  is a network interface card, which routes IP packets to/from IP transport  540  and Ethernet  340 . The invention is not limited to this embodiment. As one skilled in the art would know, there are other embodiments, such as ATM, which could be used to transport IP packets within MPT  330  and external transport  340 .  
         [0058]    Additionally, transceivers CT  520  and DT  530  have the ability to transmit and receive data to access terminals via the use of one common antenna, as illustrated. In an alternative embodiment, transceivers CT  520  and DT  530  have the ability to transmit and/or receive data via the use of a plurality of two or more antennas.  
         [0059]    [0059]FIG. 6A is a network diagram that illustrates the entities that are used in an Internet data connection when an access terminal  110  has a wireless data communication channel open with a single access point  220 . In FIG. 6A, the following labels are applied.  
         [0060]    In the exemplary Internet data connection, access terminal  110  transmits and receives IP packets embedded within PPP packets by embedding the PPP packets, or portions thereof, into wireless packets that adhere to the wireless protocol.  
         [0061]    The entities diagrammed within access point  220 A are only those entities that are part of the data path for the Internet data connection. For instance, although only a single MPT, MPT  330 AA, is diagrammed, there may be other MPTs  330  within access point  220  that are not part of the Internet data connection in question. DC  430 AA has an IP address of IP DCOAA  associated with it for use in communicating with NAS  272 , and DC  430 AA has an IP address of IP DCTAA  for use in communicating with one or more instances of MPT  330 . MPT  330 AA is an instance of MPT  330 , earlier described in reference to FIG. 3 and FIG. 5.  
         [0062]    Wireless protocol packets are transmitted between MPT  330 AA and access terminal  110  over wireless transport  610 .  
         [0063]    [0063]FIG. 6B is a diagram showing the exemplary data flow for the Internet data connection adhering to the data path illustrated in FIG. 6A. On the forward link, an IP packet having a destination IP address associated with access terminal  110  travels from Internet  124  over ethernet transport  280 E to NAS  272 . In NAS  272 , the packet is encapsulated in a PPP packet, which is further encapsulated into an L2TP packet with a destination IP address associated with DC  430 AA (IP DCOAA ), located within MPC  320 A. L2TP is well known to those skilled in the art of networking, and is described in IETF RFC 2661. This L2TP packet is transmitted over ethernet transport  280 D to router  260 . Router  260  forwards this L2TP packet over Ethernet transport  280 C to router  350 A. Router  350 A then forwards this L2TP packet over Ethernet transport  340 A to its destination of DC  430 AA. DC  430 AA, located in MPC  320 A, receives the L2TP packet and unencapsulates the embedded PPP frame. DC  430 AA, then, encapsulates the PPP frame into one or more wireless protocol capsules, which are further encapsulated into IP packets with a destination address associated with MPT  330 AA. These IP packets are then transmitted over ethernet link  340 A to MPT  330 AA. MPT  330 AA unencapsulates the wireless protocol capsules from the IP packets and transmits these capsules to access terminal  110  over wireless transport  610 .  
         [0064]    As is easily understood by one skilled in the art, the opposite path is taken for packets traveling in the direction of the reverse link. It is also easily understood by one skilled in the art that various link layer protocols exist that could be used in lieu of PPP and L2TP.  
         [0065]    [0065]FIG. 7A is a network diagram that illustrates the entities that are used in an Internet data connection when access terminal  110  has a wireless data communication channel open with two access points  220 . In particular, FIG. 7A illustrates the network entities that would be in use if access terminal  110  was previously connected as diagrammed in FIG. 6A, and subsequently access terminal  110  went into a soft-handoff with access point  220 B. In FIG. 7A, all labels have the same meaning as they did in reference to FIG. 6A, with the one following exception.  
         [0066]    Access point  220 B was not present in FIG. 6A. The entities diagrammed within access point  220 B are only those entities that are part of the data path for the aforementioned Internet data connection. Wireless protocol packets are transmitted between MPT  330 BA and access terminal  110  over transport  610 . Although, MPT  330 BA is different from MPT  330 AA, since access terminal  110  receives an aggregate signal from these MPTs  330 , it is considered a single transport  610 .  
         [0067]    [0067]FIG. 7B is a diagram showing the exemplary data flow for the Internet data connection adhering to the data path illustrated in FIG. 7A. On the forward link, an IP packet having a destination IP address associated with access terminal  110  travels from Internet  124  over ethernet transport  280 E to NAS  272 . In NAS  272 , the packet is encapsulated in a PPP packet, which is further encapsulated into an L2TP packet with a destination IP address DC  430 AA (IP DCOAA ), located within MPC  320 A. This L2TP packet is transmitted over ethernet transport  280 D to router  260 . Router  260  forwards this L2TP packet over Ethernet transport  280 C to router  350 A. Router  350 A then forwards this L2TP packet over Ethernet transport  340 A to its destination of DC  430 AA. DC  430 AA, located in MPC  320 A, receives the L2TP packet and unencapsulates the embedded PPP frame. DC  430 AA, then, encapsulates the PPP frame into one or more wireless protocol capsules, which are further encapsulated into IP packets having a destination address(es) associated with MPT  330 AA and MPT  330 BA.  
         [0068]    The packets destined for the IP address associated with MPT  330 AA are received by MPT  330 AA via ethernet transport  340 A. MPT  330 AA unencapsulates the wireless protocol capsules from the IP packets and transmits the wireless protocol capsules to access terminal  110  over wireless transport  610  at the times designated in the IP packets.  
         [0069]    The packets destined for the IP address associated with MPT  330 BA are received by router  350 A via Ethernet transport  340 A. Router  350 A forwards these IP packets over Ethernet transport  280 C to router  350 B. Router  350 B forwards these IP packets over Ethernet transport  340 B to its destination of MPT  330 BA. MPT  330 BA unencapsulates the wireless protocol capsules from the IP packets, and transmits the wireless protocol capsules to access terminal  110  over wireless transport  610  at the time designated in the IP packets.  
         [0070]    In one embodiment, the timestamps in the IP packets are such that the same internet payload is transmitted both from MPT  330 AA and MPT  330 BA over link  610  at the same time.  
         [0071]    As is easily understood by one skilled in the art, the opposite path is taken for packets traveling in the direction of the reverse link.  
         [0072]    [0072]FIG. 8A is a network diagram that illustrates, with one exception (MPC  320 B), the entities that are used for forward and reverse link data flow in an Internet data connection when access terminal  110  has a wireless data communication channel open with a single access point  220 B, but in which the capsules received by access point  220 B are transmitted to an MPC  320 A within another access point  220 A. In particular, FIG. 8A illustrates the network entities that would be in use if access terminal  110  was previously connected as diagrammed in FIG. 7A, and subsequently the link between access terminal  110  and access point  220 A was terminated. In other words, FIG. 8A can represent the entities associated with a given Internet data connection, just after access terminal  110  completes a soft hand-off. Alternatively, FIG. 8A illustrates the network entities that would be in use if access terminal  110  was previously connected as diagrammed in FIG. 7A, and subsequently a hard-handoff to MPT  330 B within access point  220 B was performed. In FIG. 8A, all labels have the same meaning as they did in reference to FIG. 7A.  
         [0073]    There is one entity diagrammed in FIG. 8A, MPC  320 B, the exception mentioned above, which is not used for the forward and reverse link data flow of said Internet data connection. This entity, MPC  320 B, is an instance of MPC  320 , earlier described in reference to FIG. 3 and FIG. 4. The use of MPC  320 B will be further described in reference to FIGS. 9 and 10.  
         [0074]    [0074]FIG. 8B is a diagram showing the exemplary data flow for the Internet data connection adhering to the data path illustrated in FIG. 8A. On the forward link, an IP packet having a destination IP address associated with access terminal  110  is travels from Internet  124  over ethernet transport  280 E to NAS  272 . In NAS  272 , the packet is encapsulated in a PPP packet, which is further encapsulated into an L2TP packet with a destination IP address associated with DC  430 AA (IP DCOAA ), located within MPC  320 A. This L2TP packet is transmitted over ethernet transport  280 D to router  260 . Router  260  forwards this L2TP packet over Ethernet transport  280 C to router  350 A. Router  350 A then forwards this L2TP packet over Ethernet transport  340 A to its destination of DC  430 AA. DC  430 AA, located in MPC  320 A, receives the L2TP packet and unencapsulates the embedded PPP frame. DC  430 AA, then, encapsulates the PPP frame into one or more wireless protocol capsules, which are further encapsulated into IP packets with a destination address associated with MPT  330 BA.  
         [0075]    The packets destined for the IP address associated with MPT  330 BA are received by router  350 A via Ethernet transport  340 A. Router  350 A forwards these IP packets over Ethernet transport  280 C to router  350 B. Router  350 B forwards these IP packets over Ethernet transport  340 B to its destination of MPT  330 BA. MPT  330 BA unencapsulates the wireless protocol capsules from the IP packets, and transmits the wireless protocol capsules to access terminal  110  over wireless transport  610 .  
         [0076]    As is easily understood by one skilled in the art, the opposite path is taken for packets traveling in the direction of the reverse link.  
         [0077]    FIGS.  9 A- 9 B are a flowchart illustrating an exemplary embodiment of the anchor point transfer methodology of the present invention. The methodology presents a means by which an entity that exists in one location in a network can be moved to another location in the network, and wherein such methodology results in a very efficient use of the bandwidth of the network.  
         [0078]    It is worth noting that at the time at which block  1000  is reached, MPC  320 A has the ability to route packets to IP DCOM  at a nominally high cost. This cost, although nominally high, is the lowest cost route associated with the delivery of packets in network  120  to IP address IP DCOAA .  
         [0079]    In block  1000 , a first MPC  320  makes the decision that one of its DCs  430  should be moved to a second MPC  320  within the network. In the exemplary embodiment of the present invention, such a decision would be made when in a Internet data connection, the DC  430  resources of one access point  220  are utilized, but wherein said DC  430  does not communicate with any MPT  330  within the same access point  220 . FIGS. 8A and 8B provide illustrations of an exemplary embodiment of a network at an instant in which it is desirable to implement the methodology of the present invention. FIGS. 10A and  10 B provide illustrations of an exemplary embodiment of a network at an instant immediately following the utilization of the methodology of the present invention.  
         [0080]    For the sake of clarity and simplicity, FIGS.  9 A- 9 B are hereafter described with specific reference to the entities referenced in FIGS. 8A, 8B,  1 OA, and  1 OB, whenever possible. However, one skilled in the art will appreciate that the invention herein is not limited to the specific entities or network configurations of those figures. Referencing FIG. 8A, in block  1000 , MPC  320 A makes the decision to move DC  430 AA from MPC  320 A to MPC  320 B. The process then moves to block  1010 .  
         [0081]    In block  1010 , MPC  320 A sends a message to MPC  320 B. The message contains a request for MPC  320 B to begin setting up a DC  430  that contains network interface related information, such as NAS communication information, equivalent to that in DC  430 AA. In the exemplary embodiment, the message contains the L2TP tunnel state information associated with DC  430 AA, such as its IP address, IP DCOAA , and the Tunnel ID of its L2TP session. The process then moves to block  1020 .  
         [0082]    In block  1020 , MPC  320 B receives the message referenced in block  1010 . In accordance with the message request, MPC  320 B allocates resources for a new DC  430 . The new DC  430  is initialized to the L2TP tunnel values received in the aforementioned message. Although this new DC  430 , present in MPC  320 B has been created and initialized, it is not used in a Internet data connection at this point. The process then moves to block  1030 .  
         [0083]    In block  1030 , MPC  320 B sends a message to its local router, router  350 B, stating that MPC  320 B has the ability to route packets to IP DCOAA  at a nominally low cost. In the exemplary embodiment, this message is an OSPF link state advertisement (LSA). In one embodiment, the message sent is an IP broadcast or multicast message, thus allowing a plurality of local routers to receive the message. The routing cost advertised in this message, being nominally low, is lower than the nominally high cost route that is currently associated with MPC  320 A. As all of the routers in network  120  are OSPF capable, this new low cost route, for packets having a destination address of IP DCOAA , will propagate throughout the routers of network  120 . Thus, at some point in the future, after the propagation of the routing information takes place, routers will begin to route packets having a destination address of IP DCOAA  to MPC  320 B. The process then moves to block  1040 .  
         [0084]    In block  1040 , MPC  320 B sets a first timer. The timer is set to a value representative of the maximum amount of time it should take for the low cost route, mentioned in reference to block  1030 , to propagate throughout network  120 . The process then moves to block  1060 .  
         [0085]    The methodology of the present invention is such that the process does not move to block  1070  until it can be assured that the propagation of the low cost route throughout network  120  has taken place. The step that is represented by block  1060  is that in which that assurance is gained. In block  1060 , MPC  320 B checks whether said first timer has expired or whether it has received a packet destined for IP DCOAA . If neither event has occurred, the process returns to block  1060 , where the same check is again performed. In block  1060 , if either said first timer has expired, or MPC  320 B has received a packet destined for IPDCOAA, then the process moves to block  1070 .  
         [0086]    In block  1070 , MPC  320 B sends a message to MPC  320 A. The message contains a request that MPC  320 A complete the transfer of DC  430 AA to MPC  320 B.  
         [0087]    In block  1080 , MPC  320 A receives the aforementioned message. In response, MPC  320 A sends a message to its local router, stating that packets with an IP destination address of IPDCOAA and packets with an IP destination address of IP DCTAA  should no longer be routed to MPC  320 A. In the exemplary embodiment, this message is an OSPF LSA. In one embodiment, the message sent is an IP broadcast message, thus allowing a plurality of local routers to receive the message. As all of the routers in network  120  are OSPF capable, the fact that MPC  320 A is no longer functioning as a router for packets having destination addresses associated with DC  430 AA will propagate throughout the routers of network  120 . Thus, at some point in the future, after the propagation of the routing information takes place, routers will no longer associate MPC  320 A as a router that can be used when trying to route packets to DC  430 AA. The process then moves to block  1090 .  
         [0088]    In block  1090 , MPC  320 A sends a message to MPC  320 B. The message contains transceiver (e.g., MPT) communication information, such as IP DCTAA  and the IP address of MPT  330 BA. Additional information useful to the transfer of DC  430 AA from MPC  320 A to MPC  320 B may also be included. In one embodiment, RLP state information is contained in the message. In another embodiment, the wireless protocol&#39;s Layer 2 state information is contained in the message. The process then moves to block  1100 . Layer 2 is a layer of the telecommunications system that provides for the correct transmission and reception of signaling messages, including partial duplicate detection. This is known to one skilled in the art, and is described in Telecommunications Industry Association TIA/EIA/IS-95-B, entitled “MOBILE STATION-BASE STATION COMPATIBILITY STANDARD FOR DUAL-MODE WIDEBAND SPREAD SPECTRUM CELLULAR SYSTEMS”, incorporated by reference herein, and hereinafter referred to as IS-95-B.  
         [0089]    In block  1100 , MPC  320 A deallocates all of its resources associated with DC  430 AA. The process then moves to block  1110 .  
         [0090]    In block  1110 , MPC  320 B receives the message that had been transmitted by MPC  320 A, described in reference to block  1090 . In accordance with the receipt of this message, MPC  320 B completes the initialization of the new DC (the one referenced in the description of block  1020 ) by initializing said new DC to the values received in this message. At this point, said new DC in MPC  320 B is configured essentially the same as was DC  430 AA in MPC  320 A, prior to its deallocation specified in block  1100 . Thus, although the new DC in MPC  320 B is physically housed in a different location than was DC  430 AA, which was housed in MPC  320 A, the two DCs are in essence one and the same. Thus, at this point, considering that DC  430 AA was deallocated in block  1100 , and considering that the new DC is essentially the same as the deallocated one, the new DC in MPC  320 B is hereinafter termed DC  430 AA, and is illustrated as such in FIG. 10A. The process then moves to block  1120 .  
         [0091]    In block  11120 , MPC  320 B sends a message to its local router, router  350 B, stating that MPC  320 B has the ability to route packets to IP DCTAA  at a nominally low cost (a cost lower than the cost previously associated with the routing of this address to MPC  320 A). In the exemplary embodiment, this message is an OSPF link state advertisement. As all of the routers in network  120  are OSPF capable, this new low cost route, for packets having a destination address of IP DCTAA , will propagate throughout the routers of network  120 . Thus, at some point in the future, after the propagation of the routing information takes place, routers will begin to route packets having a destination address of IP DCTAA  to MPC  320 B. Due to the fact that all such packets originate from MPT  330 BA, and the fact that MPT  330 BA is on the same subnet as MPC  320 B, in all likelihood this operation will be extremely fast. Gratuitous ARP, a term known those skilled in the art of networking, refers to the generation of an unsolicited ARP. In one embodiment, MPC  320 B sends a gratuitous ARP message to all other members of its subnet, informing those entities that all packets with at destination address of IP DCTAA  should be sent to the ethernet hardware address of MPC  320 B. Although not necessary, the use of the gratuitous ARP by itself, or in conjunction with an OSPF message, can decrease the amount of time it takes for packets from MPT  330 BA to be routed to MPC  320 B. The process then moves to block  1130 .  
         [0092]    In block  1130 , MPC  320 B sets a second timer. The timer is set to a value representative of the maximum amount of time it should take for the low cost route, mentioned in reference to block  1120 , to propagate throughout network  120 . In the exemplary embodiment, this second timer is set to the same value that the first timer was set to in block  1040 . The process then moves to block  1140 .  
         [0093]    The methodology of the present invention is such that the process does not move to block  1150  until it can be assured that the aforementioned propagation of the low cost route throughout network  120  has taken place. The step that is represented by block  1140  is that in which that assurance is gained. In block  1140 , MPC  320 B checks whether the second timer has expired or whether it has received a packet destined for IP DCTAA . If neither event has occurred, the process returns to block  1140 , where the same check is again performed. In block  1140 , if either the second timer has expired, or MPC  320 B has received a packet destined for IP DCTAA , then the process moves to block  1150 .  
         [0094]    In block  1150 , MPC  320 B sends zero or more messages to access terminal  110  over transport  610 . In the exemplary embodiment, the newly initialized DC  430 AA contains neither the RLP state nor the wireless Layer 2 state that was present in DC  430 AA when it resided in MPC  320 A. Thus, in the exemplary embodiment, DC  430 AA transmits messages to access terminal  110 , requesting that access terminal  110  reset its RLP and wireless Layer 2 layers. In an alternative embodiment, DC  430 AA contains all the state information that was contained in DC  430 AA when it resided in MPC  320 B. In such a case, no messages are transmitted to access terminal  110 , in this block  1150 . The process then moves to block  1160 .  
         [0095]    The methodology of the present invention is such that the process does not move to block  1170  until it can be assured that the aforementioned propagation of both low cost routes throughout network  120  has taken place. The step that is represented by block  1160  is that in which that assurance is gained. In block  1160 , MPC  320 B checks whether the second timer has expired. In the exemplary embodiment, the first timer will always have expired at the point at which the second timer has expired. If the second timer has not expired, the process returns to block  1160 , where the same check is again performed. In block  1160 , if the second timer has expired, then the process moves to block  1170 . In one embodiment, block  1140  is not present, and the process moves straight from block  1150  to block  1170 . In another embodiment, block  1160  checks for the expiration of the first timer rather than the second timer.  
         [0096]    In block  1170 , MPC  320 B sends a message to its local router, router  350 B, stating that MPC  320 B has the ability to route packets to IP DCOAA  and IP DCTAA  at a nominally high cost. In the exemplary embodiment, this message is an OSPF link state advertisement (LSA). In one embodiment, the message sent is an IP broadcast message, thus allowing a plurality of local routers to receive the message. The routing cost advertised in this message is nominally high. As all of the routers in network  120  are OSPF capable, this new nominally high cost route, for packets having destination addresses of IP DCOAA  and IP DCTAA , will propagate throughout the routers of network  120 . Thus, at some point in the future, after the propagation of the routing information takes place, the routers will replace the nominally low costs associated with routing these packets to MPC  320 B with nominally high costs. This step, puts network  120  in a state wherein the methodology of the present invention could once again be used, at a later point in time, to move DC  430 AA from MPC  320 B to another MPC  320  located within network  120 . The process then moves to block  1180 .  
         [0097]    In block  1180 , the process of the methodology of the present invention is complete. One skilled in the art will appreciate that FIGS.  9 A- 9 B provide an ordering of the steps for the exemplary embodiment of the methodology of the present invention. One skilled in the art will appreciate that several of the steps can be reordered without departing from the scope and spirit of the invention.  
         [0098]    The exemplary embodiment of the methodology of the present invention is a novel method for moving an entity containing an IP address from one location to another within a network. Not only is this methodology ideal for transparently moving an anchor point within a decentralized serving network of a wireless telecommunications system, but it is also ideal for moving an IP address throughout a corporate or campus network.  
         [0099]    The use of OSPF in the exemplary embodiments overcomes some of the drawbacks that might be encountered in a system that uses Mobile IP.  
         [0100]    The first drawback of Mobile IP is that IP packets are susceptible to taking very indirect routes. For instance, take the case where a first node moves from its home network to a foreign network, in which a second node already resides. In such an instance, if the second node sends one or more packets to the IP address assigned to the first node, all such packets will be routed from the foreign network to the visiting network, and then tunneled back to the foreign network. The use of these indirect routes introduces latency and causes more bandwidth to be used than would have been had a direct route been taken and no extra tunneling been needed.  
         [0101]    The second drawback of Mobile IP is the extra overhead that Mobile IP adds to each packet. In Mobile IP, packets routed from a Home Agent to a Foreign Agent are encapsulated, thus using extra bandwidth to support this overhead.  
         [0102]    The third drawback of Mobile IP is its lack of built-in redundancy support. With Mobile IP, if the Home Agent crashes, a mobile node visiting a foreign network will be unable to receive packets, because the existing Mobile IP standards do not address the issue of providing Home Agent redundancy.  
         [0103]    The present invention provides mobility within a network using a novel methodology that does not suffer from any of the aforementioned drawbacks. Thus, the invention can provide great efficiencies in networks other than those that function as the serving network of a wireless telecommunications system. Multiple alternative embodiments exist that support the use of the methodology of the present invention in various networks. In one embodiment, an entity containing an IP address, such as a laptop computer, frequently sends a broadcast (or multicast) link state advertisement containing an Age field that is slightly lower than the value of MaxAge. These link state advertisements contain a cost (metric) equal to a constant value that is nominally low. Thus, when the entity moves from one subnet in the network to another, its old advertisements on the old subnet, containing a nominally low metric, quickly reach MaxAge and expire. And, on the new subnet, the new advertisements with the same nominally low metric quickly take hold, allowing packets to be routed to the new location without the need for a tunneling protocol like Mobile IP.  
         [0104]    The invention herein uses OSPF as a cost efficient and standardized means for moving an entity throughout a network, which is a novel use when compared to the original intention of the OSPF protocol.  
         [0105]    In the narrower scope of the present invention, the methodology that allows for the moving of an anchor point specifically within a wireless telecommunications system, alternative embodiments exist. One such alternative embodiment utilizes Mobile IP to achieve its goal of transparent mobility of an anchor point within a wireless telecommunications system. In such an embodiment, each DC  430  is associated with a plurality of one or more home agents. In one embodiment, the OSPF messages described in reference to FIGS.  9 A- 9 B would be replaced by Mobile IP registration messages that would be sent by each DC  430  upon its movement from one portion of the system to another.  
         [0106]    [0106]FIG. 1OA is a network diagram that illustrates the entities that are used in an Internet data connection when access terminal  110  has a wireless data communication channel open with a single access point  220 B after the method of the present invention, described in reference to FIG. 9, has been utilized. In particular, FIG. 10A illustrates the network entities that would be in use if access terminal  110  was previously connected as diagrammed in FIG. 8A, and subsequently the methodology of the present invention, described in reference to FIGS.  9 A- 9 B, was utilized. Alternatively, FIG. 10A illustrates the network entities that would be in use if access terminal  110  was previously connected as diagrammed in FIG. 6A, and subsequently a hard-handoff to access point  220  was performed, in which the methodology of the present invention, described in reference to FIGS.  9 A- 9 B, was utilized. Alternatively, FIG. 10A illustrates the network entities that would be in use if access terminal  110  was previously connected as diagrammed in FIG. 7A, and subsequently a hard-handoff to access point  220  was performed, in which the methodology of the present invention, described in reference to FIGS.  9 A- 9 B, was utilized.  
         [0107]    In FIG. 10A, all labels have the same meaning as they did in reference to FIG. 8A, with one exception, as follows. As was explained in reference to FIG. 9, DC  430 AA physically located within MPC  320 B is a copy of the DC  430 AA that was physically located within MPC  320 A. Although the DCs exist within different MPCs and therefore use a different pool of resources, and could therefor have been given different labels, the DCs are given the same label of  430 AA. This is done to illustrate that both of the aforementioned DCs have all of the same attributes, including IP addresses, and perform the same functions, irrespective of their different locations.  
         [0108]    [0108]FIG. 10B is a diagram showing the exemplary data flow for the Internet data connection adhering to the data path illustrated in FIG. 10A. On the forward link, an IP packet having a destination IP address associated with access terminal  110  is travels from Internet  124  over ethernet transport  280 E to NAS  272 . In NAS  272 , the packet is encapsulated in a PPP packet, which is further encapsulated into an L2TP packet with a destination IP address associated with DC  430 AA (IP DCOAA ), which has been relocated to MPC  320 B. This L2TP packet is transmitted over ethernet transport  280 D to router  260 . Router  260  forwards this L2TP packet over Ethernet transport  280 C to router  350 B. Router  350 B then forwards this L2TP packet over Ethernet transport  340 B to its destination of DC  430 AA. DC  430 AA, located in MPC  320 B, receives the L2TP packet and unencapsulates the embedded PPP frame. DC  430 AA, then, encapsulates the PPP frame into one or more wireless protocol capsules, which are further encapsulated into IP packets with a destination address associated with MPT  330 AA. These IP packets are then transmitted over ethernet link  340 A to MPT  330 AA. MPT  330 AA unencapsulates the wireless protocol capsules from the IP packets and transmits the wireless protocol capsules to access terminal  110  over wireless transport  610 .  
         [0109]    As is easily understood by one skilled in the art, the opposite path is taken for packets traveling in the direction of the reverse link.  
         [0110]    [0110]FIG. 11 is a functional block diagram of a preferred embodiment of a decentralized serving network of a wireless telecommunications system. This preferred embodiment is an alternate embodiment to the exemplary embodiment illustrated in FIG. 2. This preferred embodiment differs from the exemplary embodiment as follows.  
         [0111]    In FIG. 11, access points  220  communicate with external devices in network  120  via transport T1  1120 . This contrasts to FIG. 2, in which access point  220  communicates with external devices in network  120  via ethernet  280 . It is easily understood by one skilled in the art that transport T1  1120  is one of a variety of transports, such as E1or microwave, which can be used for connecting access points  220 .  
         [0112]    In FIG. 11, packets sent from one access point  220 A to another access point  220 N must first travel through one or more routers  260 . This is because, as illustrated, each access point is on its own physical subnet. This contrasts with FIG. 2, in which packets can be sent directly from one access point  220  to another access point  220  over a single transport. As illustrated in the exemplary embodiment, FIG. 2, this is possible in the exemplary embodiment because transport  280  connects to all access points  220 . It is easily understood by one skilled in the art that in a network containing more than one subnet, each subnet need not be restricted to a single access point  220 . In other words, it is easily understood by one skilled in the art that some subnets can contain exactly one access point  220 , while others contain more than one access point  220 .  
         [0113]    It is also easily understood by one skilled in the art that each access point in a network  120  need not use the same physical transport to communicate to other devices in the network. For example, a network  120  could be designed such that one access point  220 D communicates with a router  260  via a T1 transport, while another access point  220 E communicates with a router  260  via an E1 transport, while another access point  220 F communicates with a router  260  via another transport, such as ethernet.  
         [0114]    Finally, it is easily understood by one skilled in the art that the methodology of the present invention, described herein, works in all such embodiments of network  120 . In all such embodiments, the methodology of the present invention, described in reference to FIGS.  9 A- 9 B, remains the same. This is because the methodology of the present invention was designed to be flexible enough such that it would work in a variety of network configurations.  
         [0115]    The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.