Patent Document

RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/883,039 filed on Dec. 31, 2006, titled “COMMUNICATIONS METHODS, SYSTEM AND APPARATUS”, which is hereby expressly incorporated by reference and which is assigned to the assignee hereof. 
     
    
     FIELD 
       [0002]    Various embodiments are directed to communications methods and apparatus and, more particularly, to methods and apparatus for controlling packet forwarding using multiple mobility control nodes. 
       BACKGROUND 
       [0003]    Mobile IP (MIP) is described in a number of documents developed in the IETF (www.ietf.org). MIP provides for mobility management for a mobile node (MN) Home address (HoA) by tunneling packets at a Home Agent (HA) towards/from a MN Care of Address (CoA), at which the MN HoA is routable. MIP signaling between the MN and the HA, maintains the MN CoA/MN HoA binding at the HA, and updates it to each new CoA value as the MN moves between Access Routers, and hence across the routing topology. 
         [0004]    The MIP HA acts as both the end point for MIP signaling and also as the endpoint for MIP tunnel forwarding. The HA also issues routing adverts for the HoA prefixes at that HA, from which MNs are allocated HoAs. The MIP HA must have a security association with each MN, and also with any Foreign Agent through which the signaling traverses. This is to ensure that binding changes can only be made by authorized MIP nodes. The end result is typically a HA router platform with significant forwarding, mobility signaling and security processing responsibilities. The HA also has timely visibility of the topological location and movement of the MN which can be useful for Location Based Services, and for presence management. However, the processing and publishing of such information to application services places additional significant burdens on HA nodes. A further problem with HAs is that from a security and management perspective they should be ideally located behind a firewall in the applications server farm of the operator but this causes high volume, low value traffic to trombone through the firewall twice to visit the HA and be onward forwarded to the MN. 
         [0005]    An improved MIP HA architecture decomposes the HA functions, to separate and distribute the MIP signaling and tunneling end-points. The HA Control Node (HACN) manages the mobility signaling with the MN and FA whilst one or more HA Tunneling Nodes (HATNs) provide forwarding for packets towards the HoA of the MN. In such an approach multiple HATNs may be operated under the control of a single HACN. 
         [0006]    However, even when using multiple HATNs, the failure of the HACN still renders all MNs that undertake mobility signaling via that HACN unable to update their mobility location while it may still be possible for each HATN to forward packets correctly to MNs that remain at the same location. Therefore whether a traditional HA or a decomposed HA (HACN/HATN) is used for mobility management, the failure of the HA/HACN results in significant problems. 
         [0007]    A redundant pair of conventional HAs, synchronised with Virtual Router Redundancy Protocol (VRRP), is generally considered at the present time to be the optimal deployment configuration for an IP mobility domain, with any HA failure then being hidden from the MN/FA by the synchronization protocol with the redundant HA. As the need grows to integrate mobility events with value-adding processes, including external application servers, this centralized (hot standby) architecture becomes more and more of a bottleneck as the amount of state to be synchronized grows. Locating the two HAs in the same location renders them vulnerable to geographical/environmental failures (weather, power, attack, flood etc). In addition, the synchronization protocol performs increasingly poorly as the HAs are moved apart (increasing signaling delay) because the bindings and other state in each virtual HA become desynchronized. 
         [0008]    The use of multiple physical HAs, that do not require synchronization, is problematic because the HA manages address allocation and forwarding and so a change of HA forces a change in the MN HoA creating major disruption to ongoing sessions. In addition, the HA address and HoA is known by the MN and the FA, and so a change in HA is exposed to the MN and relies on the MN acting promptly to detect the failed HA and then move across to the spare HA. No known solution exists for that spare HA being able to provide forwarding for the HoA that was being used at the failed HA. In addition, relying on the MN to perform the recovery from the failed HA is expensive on the air-link, slow and means that customers are overly exposed to operator failures and operators rely on terminal software for the timeliness of that recovery. 
         [0009]    In view of the above discussion, it should be appreciated that there is a need for improved methods of providing packet forwarding control functions and/or packet forwarding functions, e.g., HA type functions, in a manner that provides both fault tolerance and avoids many of the problems/risks associated with locating two home agents in close proximity while avoiding some or many of the synchronization and/or control issues associated with using two conventional HAs that are located at distances from one another. 
       SUMMARY 
       [0010]    Various methods and apparatus are directed to providing enhanced functionality and fault tolerance in a system which distributes home agent functionality between a home agent control node and a tunneling node, referred to herein as a home agent tunneling node which performs packet forwarding under direction of the home agent control node. The distributed home agent approach is enhanced in accordance with the various embodiments to provide redundancy in terms of home agent control nodes and/or home agent tunneling nodes. Not all aspects discussed below are used in all embodiments and various alternative approaches are described in several instances. 
         [0011]    In accordance with some aspects if a home agent control node fails, the secondary home agent control node can take over the home agent control function. While introducing redundancy may appear to be a simple matter, to avoid the loss of packets, in many but not necessarily all applications, there is a need to be able to switch between the primary and secondary home agent control nodes in a short amount of time. Various embodiments describe various methods, apparatus, nodes and/or messages in addition to system configurations, which can be used to maintain primary and secondary home agent control in a condition, e.g., state of operation, which facilitates the rapid transferring of functions between primary and secondary nodes. Many of the features of the novel embodiments are directed to messages and methods of signaling which can be used to update information stored in the primary and second home agent control nodes, e.g., binding information which can be used for address resolution and to support packet routing. In addition, various methods are directed to methods of signaling which mode, primary or secondary, a particular home agent control node is to operate at a particular point in time. The messaging and control method of various embodiments provide an efficient way of updating/controlling the home agent control nodes state of operation as well as the information stored in these nodes which is used to provide home agent functionality to individual nodes. Novel fault detection techniques are also described which can be used to trigger a switch from a primary to a secondary node. Switching from a primary to a secondary node may cause the status of the nodes to be reversed, e.g., with the node which was operating as a secondary HA control node becoming the primary HA control node and the node which was serving as the secondary HA control node becoming the primary HA control node. 
         [0012]    It should be appreciated that methods and apparatus for providing home agent type functionality through the use of multiple distributed packet forwarding control nodes and multiple packet forwarding node are described. The methods and apparatus of various embodiments provide redundancy of both the packet forwarding control and actual packet forwarding operations while allowing the redundant nodes to be located at different physical locations thereby improving system reliability and fault tolerance. 
         [0013]    Thus, among other things, this application is directed to methods and apparatus for using multiple home agent control nodes (HACNs) to provide redundancy and/or control in a system having one or multiple Home agent tunneling nodes (HATNs) are described. In some embodiments HACNs are used to control packet forwarding, e.g., to a roaming node, by controlling a HATN to forward packets to the node, e.g., in a visited network. 
         [0014]    The methods and apparatus will be described primarily for the case of the MIP based system, but are applicable and can be used to provide the equivalent or similar control and forwarding functions in a 3GPP/CDMA2000 systems and/or other systems having similar needs. Such systems can be implemented with the same or similar signalling and tunneling functions described herein being implemented via one or more of the following system elements or future equivalents: MSC, SGSN, GGSN, PDSN, RNC, BS and MT nodes via MIP or GTP based tunneling and support signalling. Various features and methods described herein can be mapped and implemented directly using the nodes which are equivalent or similar to those described in the examples included herein, which are found in 3GPP and CDMA2000 systems and their derivatives. 
         [0015]    In various embodiments multiple HACNs are located at Points of presence (POPs) throughout the operators network, and share access to a common HA Database Function (HADF) that may be located in one of the HACNs or in a separate HA Database Node (HADN). The HADF holds information on amongst other things MNs, HACN addresses, HATN addresses, Home Address prefixes, prefix assignments to HATNs, Home Address assignments to MNs, and HATN bindings (ie mappings between MN HoAs and MN forwarding addresses). It specifically contains information on the HACNs and HATNs that support a specific HoA prefix in each part of the operators network. HATNs are allocated prefixes out of the HADF, and any assigned HACN can make adjustments to the bindings at a HATN via the HACN-HATN protocol. The AAA system is preferentially used for distributing a list of HACNs, HATNs and associated HoA prefixes, to each Access Node, located for example at the Basestation, which is refreshed on a regular basis so that HACNs and HATNs that are out of service, can be removed from the list, and changes in HACN/HATN/prefix mappings undertaken. Note that the HACNs and HATNs for a particular prefix is typically only distributed to an Access Node when a MN under that prefix exists at that Access Node. 
         [0016]    Each MN is allocated a HoA address, preferentially by the AAA system, and an associated primary and secondary HACN can be assigned. This ensures that HoA allocation state is not tied to a specific HACN. The assigned HoA, and associated HACNs are passed to the MN in the first binding response by the Access Node. The FA caches the mappings between the HACNs and prefixes, and polices messages from the MN to ensure they comply with those mappings. As the MN moves around the infrastructure, the primary and secondary HACNs offered to the MN can change. This is because multiple topologically and geographically distributed HACNs are able to be the primary HACN for the same prefix, the result being that the MNs under the same prefix in a particular part of the network would have the same primary and secondary HACNs. The MN should first try the primary HACN advertised by an FA even if that means that the MN has to relocate from another HACN. If the MN uses the wrong HACN then the FA could replace the HACN value and return the new value in the binding response. 
         [0017]    When a MN fails to get a response from the primary HACN to a binding update, then the MN needs to be in a position to take appropriate action. The failed response could be as a result of packet loss, or failures at the FA, HACN or HATNs. The probability of two concurrent HATNs failing is much less than the probability of a HACN failure, and the FA failure is quickly detected, and avoided by the MN. The probability of the failure being due to packet loss is highest and so the FA should retransmit the binding update message, marked with a retransmit flag, or some modified identifier, to the primary HACN after timer T 1 . T 1  could be set to be significantly greater than (default 2.5 times) the normal round trip time via the HACN and the HATNs (RTT 1 ). If both the initial and retransmitted binding update requests are not answered after timer T 2  (ie default 6 times RTT 1 ), then the MN redirects the binding update to the secondary HACN. It may be possible, and preferable, for this redirection to be handled by the FA, with the response to the binding update informing the MN of the HACN change. 
         [0018]    In some embodiments, a strict ordering is generated by the MN for its binding. It is possible to have the FAs generate this order identifier to save air-link resources. A combination of one, two or three identifiers can be used to manage this ordering, the identifiers being generated at a number of different nodes. The binding updates are strictly ordered so that the FA, HACN, HADF and multiple HATNs can detect duplicates and retransmissions, and so they are never confused about which is the latest binding update that is associated with a specific MN HoA, and which HACN is managing a specific prefix at each HATN. This order identifier is carried in the messages via the FA to the HACN, through to the redundant HATNs, and then returned in the HATN responses back through the HACN to the MN. It is possible to return a different identifier as long as its value is a function of information in the received message and shared information between the nodes on the signalling path, so that the returned identifier can be verified for ordering and security purposes. The current HACN that is managing the current binding for a MN at a HATN may be displaced when another HACN updates that binding using an increased order identifier, or when a higher priority is indicated or when performance information indicates that a different HACN should be used. 
         [0019]    Events at the HATN associated with a binding such as performance statistics, are reported to the current HACN or the spare HACN. In an exemplary embodiment, these events are not reported to the secondary HACN because a failed primary HACN will be bypassed by the MN, and the HATN will then inform the secondary HACN in its response. Each new binding update for a specific MN HoA acknowledges the events previously received from a HATN so that the HATN tracks successful reception and storage of these events at the HADF. 
         [0020]    When a primary HACN for a specific HoA prefix fails, a large number of MNs under the affected HoA prefixes will normally lose their mobility management capability. These MNs will be in the same topological part of the network, and multiple MNs will likely be at the same secondary HACN, FAs and HATNs. This ensures that the failure mechanisms are efficient in terms of HADF, HACN, FA and HATN processing, messaging and state. The first binding update towards the failed primary HACN will inform the FA and then the HATNs of the primary failure, and the switch to the secondary HACN, The FA can then cache this failure information and immediately redirect all binding updates from MNs at that FA employing prefixes from that HACN, to the secondary HACN, and hence avoid timer T 1 , T 2 . This failure information will also be rapidly propagated to neighbouring Access Nodes as a result of hand-offs, and the associated state transfer between Access Nodes. Failure information will reach the HADF, and result in distribution of the HACN change (ie becoming the new primary) to the rest of the FAs in the infrastructure via the AAA messages. The secondary HACN learns of the primary HACN failure from the redirected binding update, and hence can start to accumulate local state associated with the affected HoA prefixes from the AAA and HADF. The affected HATN will also be informed of the primary HACN failure from the redirected binding update, and can cease transmitting information to the primary HACN and redirect messages to the secondary HACN for the affected HoA prefix. 
         [0021]    Depending on the particular embodiment, HATNs can request changeover to another HACN, or the old or new HACN can direct the HATN to change to the new HACN as a result of specific messages or indirectly as a result of updated binding messages being received from a new HACN. The Access Node or the MN can direct binding information messages towards either the old or new HACN as a result of time or load based sharing, priority indications, or performance tracking of the HACNs. When changeover signalling is conducted via a separate HADN then the HADN passes messages between the two HACNs. 
         [0022]    An exemplary method of operating a communications system including a first node, e.g., first HATN, a second node, e.g., first HACN, a third node, e.g., second HATN, a fourth node, e.g., second HACN, and an access node, comprises: operating the second node to send a first message, e.g., first forwarding information message, to the first node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via one of the first node and the third node, in addition to an access node; operating the second node to receive a change request message from the first node requesting that the second node stop providing forwarding information to the first node for packets including said mobile node address; and operating the fourth node to transmit a second message, e.g., second forwarding information message, to the first node that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and an access node. 
         [0023]    An exemplary communications system, for use with a first network node, e.g., a first HATN, and a third network node, e.g., a second HATN, and an access node, comprises: a second network node, e.g., a first HACN, including: i) a first message module for generating and sending a first message, e.g., first forwarding information message, to the first node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via one of the first and the third nodes, in addition to said access node; ii) a change request processing module for receiving a change request message from the first node requesting that the second node stop providing forwarding information to the first network node for packets including said mobile node address; and a fourth network node, e.g., second HACN, including a second message module for generating and sending a second forwarding information message from the fourth network node to the first node the second forwarding information message including second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and an access node. 
         [0024]    An exemplary method of operating a first node, e.g., first HATN, in a system including said first node, a second node, e.g., first HACN, a fourth node, e.g., a second HACN, and an access node, comprises: operating the first node to receive a first message from the second node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via the first node and an access node; and operating the first node to receive a second message from the fourth node, e.g., second HACN, that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and said access node. An exemplary first node, e.g., first HATN, for use in a communications system including said first node, a second node, e.g., first HACN, a fourth node, e.g., second HACN, and an access node, said first node comprises: a first message processing module for receiving and processing a first message from the second node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via the first node and an access node; and a second message processing module for receiving and processing a second message from the fourth node, the second message including second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and said access node. 
         [0025]    The above described features are only a few of the many features and embodiments described in the present application and are not to be considered a summary of all the features or elements. Numerous additional features and embodiments are described in the detailed description which follows. 
         [0026]    While various embodiments have been discussed in the summary above, it should be appreciated that not necessarily all embodiments include the same features and some of the features described above are not necessary but can be desirable in some embodiments. Numerous additional features, embodiments and benefits are discussed in the detailed description which follows. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0027]      FIG. 1  shows an exemplary network illustrating exemplary elements of various embodiments. 
           [0028]      FIG. 2  shows prior art Mobile IP (MIP) signaling between a mobile node (MN), a foreign agent (FA) and a home agent (HA). 
           [0029]      FIG. 3  illustrates equivalent prior art MIP based signaling flows for a home agent control node/home agent tunneling node (HACN/HATN) combination as opposed to a traditional HA based system. 
           [0030]      FIG. 4  illustrates exemplary nodes, state, signaling and methods of various exemplary novel embodiments from the perspective of a first node, e.g., a home agent tunneling node. 
           [0031]      FIG. 5  illustrates exemplary nodes, state, signaling and methods of various exemplary novel embodiments from the perspective of an access node. 
           [0032]      FIG. 6  illustrates an alternative set of signaling and methods that can be used at an Access Node to support multiple HACNs. 
           [0033]      FIG. 7  illustrates exemplary nodes, state, signaling and methods of various exemplary novel embodiments from the perspective of exemplary second and fourth nodes, e.g., HACNs, wherein the second node and the fourth node control the forwarding performed by the first node and the third node, e.g., HATNs, to a MN. 
           [0034]      FIG. 8  shows an exemplary Home Agent Database which can be located in a second node, e.g., HACN node, fourth node, e.g., another HACN node, or in the Another node, e.g., Home Agent Database Node or AAA node, or distributed between these nodes. 
           [0035]      FIG. 9  is a drawing of an exemplary state diagram for an exemplary tunneling agent (TA) node in accordance with various embodiments. 
           [0036]      FIG. 10  is a drawing of an exemplary state diagram for an exemplary tunneling agent (TA) node in accordance with various embodiments. 
           [0037]      FIG. 11  is flowchart of an exemplary method of operating an access node in accordance with various embodiments. 
           [0038]      FIG. 12  is a flowchart of an exemplary method of operating a communications system in accordance with various embodiments. 
           [0039]      FIG. 13  is a flowchart of an exemplary method of operating a communications system in accordance with various embodiments. 
           [0040]      FIG. 14  is a flowchart of an exemplary method of operating a communications system in accordance with various embodiments. 
           [0041]      FIG. 15  is a flowchart of an exemplary method of operating a communications system in accordance with various embodiments. 
           [0042]      FIG. 16  is a flowchart of an exemplary method of operating a communications system in accordance with various embodiments. 
           [0043]      FIG. 17  is a flowchart of an exemplary method of operating a communications system in accordance with various embodiments. 
           [0044]      FIG. 18  is a drawing of an exemplary communications system in accordance with various embodiments. 
           [0045]      FIG. 19  is drawing of an exemplary first node, e.g., an exemplary first home agent tunneling node, in accordance with various embodiments. 
           [0046]      FIG. 20  is a drawing of an exemplary access node, e.g., base station, in accordance with various embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]      FIG. 1  shows an exemplary network  100  illustrating elements of various embodiments. Mobile end node (MN)  160  is coupled to an access node  170 , e.g., an Access router and or a Basestation, by link  165 . Link  165  can be a fixed medium such as a cable, or a wireless medium such as is common in cellular systems. The Access Node  170 , in some embodiments, contains a Foreign Agent or Attendant Agent in a Mobile IP based mobility management system. The Access Node  170  is coupled to a network node  190  via a link  175 . Network node  190  is coupled to a network node  191  via link  195 . The MN  160  can alternatively be coupled via link  165 ′ to Access Node  170 ′ which itself is coupled to node  190  via link  175 ′. Node  191  is further coupled to a network node  192  via link  196  and to Another Node  180  e.g., a HADN or AAA, via link  185 . Network node  191  is coupled via link  155  to a Correspondent Node (CN)  150  which is also an end node. CN  150  may participate in the reception and transmission of IP packets in a communications session with the Mobile Node  160 . The CN  150  has a Correspondent Address  151  whilst the MN  160  has a Mobile Node Address  161 , which for the case of Mobile IP is also called the Home Address (HoA). In such sessions, packets sent from the MN  160  to the CN  150  have a source address equal to the MN address  161 , and a destination address equal to a Correspondent Address  151  and visa versa for packets from the CN  150  to the MN  160 . Coupled to the network node  190 , via link  115 , is a first node  110  which would typically be a HATN or GGSN. Optional third node  130 , which would typically be an additional HATN or GGSN, is coupled to node  190  via link  135 . The first node and the third node ( 110 ,  130 ) are both able to support packet forwarding for packets exchanged between the CN  150  and the MN  150 . In support of that forwarding, the first node  110  injects a first routing advertisement  111  into the routing system  101  operating within the network  100 , for an address prefix that includes the MN address  161 . Similarly, the optional third node  130  injects a second routing advertisement  131  into the same routing system  101 , for an address prefix that includes the MN address  161 . Exemplary network  100  also includes a second node  120  and a fourth node  140 . The second node  120  is, for example, a HACN or MSC which is coupled to network node  191  via link  125 . Similarly, the fourth node  140  is an additional HACN or MSC which is coupled to the network node  192  via link  145 . Each of the second and fourth nodes ( 120 , 140 ) are capable of acting as a signaling endpoint for mobility signaling from the MN  160  and from the AN  170 . The second and fourth nodes ( 120 , 140 ) are then able to update forwarding information in the first node  110 , and the optional third node  130 , with each new forwarding address  171  and/or  162  of the MN  160  so that packets arriving at the first and third nodes ( 110 , 130 ) that are destined for the MN address  161 , from the CN address  151  can be forwarded towards the MN  160 . The forwarding address  171  in the Access Node  171  can be an IP address or a link layer address, and in the case of MIP could specifically be a Foreign Agent Care of Address. The forwarding address  162  can be an IP address or a link layer address. In the case of MIP it could be the MN Colocated Care of Address or it could be the link-layer address of the MN when it is sharing a Foreign Agent Care of Address with other nodes. 
         [0048]    Some of the network nodes run a routing protocol as part of the routing system  101  and the routing advertisements ( 111 ,  131 ) will be processed by the nodes performing the routing protocol to determine the next hop for packets containing the MN address  161  as for example a destination address. Said packets destined for the MN address will as a result be forwarded to either the first node  110  if only first routing message  111  is injected, or to one of the first and the third nodes ( 110 , 130 ) if both first and second routing advertisements ( 111 , 131 ) are injected. When a packet destined for the MN address arrives at one of the first and the third nodes ( 110 ,  130 ), it will be compared to the binding entries at the receiving node to identify the forwarding address  171  and/or  162  that is to be used to forward the packet towards the MN  160 . 
         [0049]    The MN  160  and/or the Access Node  170  perform mobility management signaling with the second node  120  and with the fourth node  140 , to update the forwarding address(s) to be used for packets containing the MN address  161 , such as those destined for the MN  160 . The forwarding address depends on which of the Access Nodes  170 ,  171  to which the MN  160  is connected. When the MN  160  moves from Access Node  170  to Access Node  170 ′ then the forwarding address changes from forwarding address  171  to forwarding address  171 ′ whilst the forwarding address at the MN  160  changes from forwarding address  162  to forwarding address  162 ′. The MN  160  and the Access Node  170  therefore need to obtain updated forwarding addresses and to communicate at least one of these forwarding addresses ( 171 ′,  162 ′) to at least one of the second and fourth nodes ( 120 ,  140 ). At least one of said second and fourth nodes ( 120 , 140 ) need to then signal the new forwarding address ( 171 ′,  162 ′) to the first node  110 , or to one of the first and third nodes ( 110 , 130 ) if both are able to provide forwarding for the MN address  161 . If the second node  120  is being used to update said forwarding addresses ( 171 , 171 ′,  162 , 162 ′) and it is determined that the second node  120  is no longer able to update such forwarding addresses ( 171 , 171 ′,  162 , 162 ′) then the MN  160  and/or the Access node  170  can instead send the forwarding address update to the fourth node  140 , and the fourth node  140  will then propagate the updated forwarding address ( 171 , 171 ′, 162 , 162 ′) into at least one of the first and the third nodes ( 110 , 130 ). System  100  also includes another node  180 , e.g., a HADN or AAA coupled to node  191  via link  185 . 
         [0050]      FIG. 2  shows in drawing  200  prior art Mobile IP signaling between a MN  160   a , a FA  170   a  and a HA  120   a . Message  260  is a MIP Registration Request (RREQ) message from the MN to the FA, whilst message  261  is a RREQ from the FA  170   a  to the HA  120   a . This message flow can be used to register either a MN CCoA or a FA CoA into the HA  120   a  for the HoA of the MN  160   a . The MIP Registration Reply (RREP) is from the HA  120   a  to the FA  170   a  as shown in message  262 , which is forwarded to the MN  160   a  as message  263 . This confirms the installation of the mobility binding into the HA  120   a  and FA  170   a , between the MN HoA and the MN CoA. In the case of registering a FA CoA, packet flow  264  between a CN  150   a  and the MN HoA is received at the HA  120   a , and then tunneled to the FA CoA in tunnel  265 . MIP signaling can alternatively employ a RREQ message  270  from the MN  160   a  to the HA  120   a , and a RREP from the HA  120   a  to the MN  160   a , to install a MN CCoA into the binding at the HA  120   a . Packet flow  272  shows a flow of packets between a CN  150   a  and the MN  160   a , which when received at the HA  120   a  are tunneled to the MN CCoA using tunnel  273  according to the stored binding for the MN HoA. This binding can be installed using either the signaling messages  260 ,  261 ,  262  and  263 , or alternatively messages  270  and  271 . 
         [0051]      FIG. 3  illustrates in drawing  300  the equivalent prior art MIP based signaling flows for the HACN/HATN combination as opposed to a traditional HA based system. Signaling and forwarding are described for the case of a MIP RREQ that is first directed towards the FA  170   b  and then the second node  120   b  for registering a FA CoA into the first node  110   b , and also for a RREQ directed towards the second node  120   b  to install a MN CCoA in the first node  110   b , but it should be understood that the signaling via the FA  170   b  can alternatively register a MN CCoA and hence enable a tunnel in the second node  120   b  between the third node  130   b  and the MN  160   b . It should be further understood that the signaling can alternatively be used to install a MN CCoA or FA CoA into the third node  130   b.    
         [0052]    When directed via the FA  170   b , RREQ messages  360  and  361  are employed to the second node  120   b , to install a binding between the MN address  161   b  and the FA CoA, which is the forwarding address  171   b  of the Access Node  170   b . The RREP is returned in messages  362  and  363  from the second node  120   b  to the MN  160   b  via the Access Node  170   b . However, the second node  120   b  is not the HATN which instead is the first node  110   b . Therefore, the second node  120   b  returns the address of the first node  110   b  to the access node  170   b  in message  362 , so that the access node  170   b  knows to expect tunneled packets from the first node  110   b  rather than the second node  120   b . In addition, the second node  120   b  sends a message  366  to the first node  110   b , either before or after sending the RREP  362 . Message  366  installs in the first node  110   b  the forwarding address  171   b  for the MN address  161   b  to redirect received packets towards the MNs FA CoA that has been communicated to the second node  120   b  by the MN  160   b  via the AN  170   b . Message  367  is then sent by the first node  110   b  to the second node  120   b  to confirm that the forwarding address  171   b ′ has been installed. Packet flow  364 , between the CN  150   b  and the MN  160   b , will be sent towards the first node  110   b , and then redirected to the Access Node  170   b  in tunnel  365 . If the second node  120   b  alternatively sends messages similar to  366  and  367  towards the third node  130   b  instead of the first node  110   b , then packet flow  368  between the CN  150   b  and the MN  160   b  may instead be received at the third node  130   b  and be redirected to the Access Node  170   b  by tunnel  369 , which the access node  170   b  will expect because it will have received the address of the third node  130   b  in message  362 . Finally, it should be noted that the second node  120   b  can employ messages such as  366  and  367  with both the first node  110   b  and the third node  130   b , so that either the first or third nodes  110   b , 130   b  can receive packets with a destination address equal to the MN address  161   b , and redirect the packet in a tunnel to the Access Node  170   b . This means that message  362  should include the addresses of both the first and third nodes  110   b , 130   b . If the MN  110   b , is instead registering a MN CCoA as the forwarding address  162   b  into the second node  120   b  then the first and third nodes  110   b ,  130   b  will alternatively be instructed to install forwarding state to redirect packets to that MN CCoA, and the addresses of the first and third nodes  110   b ,  130   b  will be returned to the MN  160   b  via messages  362  and  363  so that the MN  160   b  knows where it should tunnel upstream packets. 
         [0053]    Message  370  and  371  show the case of the MIP RREQ being directed at the second node  120   b  and the RREP being directed back to the MN  160   b , to register a MN CCoA into the mobility binding at the second node  120   b . Once again the second node  120   b  then issues message  374  to the first node  110   b  to install a tunnel between the first node  110   b  and the MN CCoA  162   b  of the MN  160   b . The message  375  is then sent by the first node  110   b  to the second node  120   b  to confirm installation of the direct tunnel. Again, message  371  can be sent by the second node  120   b  any time after the reception of message  370 , including after sending message  374 . The preferred method would be to send message  371  on reception and processing of message  375  so that the MN  160   b  is assured that the state in the first node  110   b  has been installed. The packet flow  372  from the CN  150   b  to the MN  160   b  is then received at the first node  110   b  and redirected to the MN  160   b  by tunnel  373 . If the third node  130   b  is instead used, then the packet flow  376  from the CN  150   b  to the forwarding address  162   b  of the MN  160   b  may be instead received at the third node  130   b  and packets redirected to the MN  160   b  using tunnel  377 . Once again, both first node and third node tunnels  373  and  377  can be installed so that packets will be forwarded to the MN  160   b  by whichever of the first node  110   b  and third node  130   b  is the preferred packet receiver for the MN address  161   b  (the MN HoA). 
         [0054]    Various novel features and aspects of various embodiments will now be described in relation to drawing  500  of  FIG. 5  from the perspective of the Access Node  170 .  FIG. 5  shows a forwarded packet  501  including mobile node address  501   a , a CNA  501   b , and a payload  501   c , the forwarded packet  501  being forwarded from the first node  110  to the MN  160  via the Access Node  170 . The access node  170  stores information  514  indicating a mapping between the MN address  515  and both second node identifier  516  and fourth node identifier  517 . The MN  160  transmits a binding update message  503  to the Access Node  170  which includes the MN address  503   a , the forwarding address  503   b , and optionally includes non-address information  503   c  and first identifier  503   d . The Access Node  170  then transmits a portion of said received binding update message  503  as message portion  505  to one of the first and second nodes  110 , 120  as indicated by the message destination field  505   a , the message portion further including a first identifier  505   b  and a second identifier  505   c . The access node  170  selects between the second and the fourth nodes  120 , 140  as the destination of said message portion  505 , one option being that the selection is based on at least some information that is included in the binding update message, such as said non-address information  503   c . The access node  170  can select the second node  120 , rather than the fourth node  140 , as the destination of message portion  505 , based on a priority indicator included in said stored mapping information, said priority indicator being associated with at least one of the second and fourth nodes such as 2 nd  node priority indicator  518  and 4 th  node priority indicator  519 . The various elements of the mapping information  514  can be updated by the reception of updated mapping information message  520  received from, for example, the second, fourth and another node  120 , 140 , 180 . This can include updates to the priority indication information  518 , 519  corresponding to one of the second and fourth nodes  120 , 140 . 
         [0055]    The access node  170  stores message portion processing performance information  561  and message portion forwarding performance information  562  regarding at least one previous message portion forwarded by said access node  170  to one of said second and fourth nodes ( 120 ,  140 ), such that the selecting of the second node  120  rather than the fourth node  140  as the destination for said message portion is performed as a function of said stored performance information. 
         [0056]    The access node  170  can execute a retransmit timer  563  associated with said forwarded message portion and then the access node  170  can retransmit said  506  message portion to the second node  120  when the retransmit timer  563  expires prior to reception of a response message portion  507  to the forwarding of said message portion  505 ,  506 . Message portion  507  can include the Mobile Node address  507   a , forwarding address  507   b , non-addr information  507   c  such as security parameters, and 1 st  and second identifiers  507   d  and  507   e.    
         [0057]    The access node  170  can execute a second node transmission failure detection process  551  and transmit at least a portion of said message portion  508  to the fourth node  140  when the second node transmission failure detection process  551  indicates a transmission failure associated with the transmission of the message portion  505  to the second node  120 . 
         [0058]    The received binding update message  503  can include a first identifier  503   d , which is included in said transmitted message portion  505  as first identifier  505   b . The access node  170  can add a second identifier  505   c  into said transmitted message portion  505 , the value of said second identifier  505   c  being different for said transmitted message portion  505  and a retransmitted message portion  506   
         [0059]    The received binding update message  503  can include a first identifier  503   d  and the access node  170  can add a second identifier  508   c  to the portion of said message portion  508  transmitted to said fourth node  140 , the value of said second identifier  508   c  being different from the value of the second identifier  505   c  included in the transmission of said message portion  505  to said second node  120 . (ie the HATN discriminates between the two messages by the 2 nd  ID value) 
         [0060]    The received binding update message  503  can include a first identifier  503   d  and the access node  170  can add a second identifier  508   c  to the portion of said message portion  508  transmitted to said fourth node  140 , the value of said second identifier  508   c  being the same as the value of the second identifier  505   c  included in the transmission of said message portion  505  to said second node  120  (ie the HATN can discriminate between the two messages because they come via different HACNs) 
         [0061]    The access node can transmit a message  509  to one of the second and fourth and another nodes  120 , 140 , 180 , including performance information  509   a  corresponding to the stored performance information. When the access node  170  receives a message including updated mapping information  520 , said updated mapping information  520  including at least one of a second node identifier  520   b  and a standby node identifier  520   c , said standby node identifier  520   c  corresponding to a standby node such as network node  192  to be used in place of said fourth node  140  with respect to processing of binding update messages  503  including said mobile node address  161 . 
         [0062]      FIG. 6  illustrates in drawing  600  an alternative set of signaling and methods that can be used at the Access Node  170  to support multiple HACNs. A forwarded packet  601  including mobile node address  601   a  is shown being forwarded by first node  110  to the MN  160  via the Access Node  170 . To support such forwarding, the access node  170  is operated to store information  614  indicating a mapping between the MN address  161  corresponding to the mobile node  160  and the second and fourth nodes  120 , 140 . This information is stored as mobile node address  615 , second node identifier  616 , and fourth node identifier  617 . The Access Node  170  is then operated to transmit a selection message  602  to the MN including second/fourth node selection information  602   b  that indicates that the MN should transmit binding update messages including the MN address towards the second node  120 . The Access Node  170  is then operated to receive a binding update message  603  from the mobile node  160 , said binding update message  603  including the MN address  603   a , a forwarding address  603   b , and a destination node identifier  603   c , said destination node identifier  603   c  identifying said second node  120  as the destination of the binding information, said forwarding address  603   b , such as addresses  171 ,  171 ′, 162 , 162 ′ being used by said first node  110  to forward packets including said MN address  161  which is included in message part  603   a . The Access Node  170  is then operated to forward a portion  605  of said binding update message  603  to the second node  120  as indicated by message destination portion  605   a  which is the destination node identifier  603   c.    
         [0063]    The second and fourth nodes ( 120 , 140 ) are nodes which process binding update signaling, using binding update signaling processes ( 127 , 147 ), respectively, for a binding between a mobile node address  161  and a forwarding address  171 , 171 ′, 162 , 162 ′ used by said first node  110  to forward packets  601  including said mobile node address. 
         [0064]    The step of operating the access node  170  to transmit selection message  602  to the MN  160  that indicates that the MN should transmit binding update messages  603  including the MN address  603   a  towards the second node  120  is performed after operating the access node  170  to select between said second and fourth nodes  120 , 140  as the destination of at least one binding update message  603  to be transmitted from the MN  160 . 
         [0065]    The access node  170  selects between the second and fourth nodes ( 120 , 140 ), using 2 nd /4 th  node selection process  650 , based on a priority indicator such as second node and fourth node priority indicators  618 , 619  that is included in said stored mapping information  614 , that is associated with at least one of the second and fourth nodes ( 120 , 140 ), said priority indicator ( 618 , 619 ) indicating that said second node  120  has priority over said fourth node  140 . 
         [0066]    The Access Node  170  is then operated to receive an updated mapping information message  620 , including updated mapping information that includes priority information  620   a  that indicates changes in priority indication information to be made to stored priority information ( 618 , 619 ) corresponding to at least one of the second and fourth nodes ( 120 , 140 ) such as updated fourth node priority information  620   a . This updated mapping information message  620  is transmitted towards the Access Node  170  by one of the second, fourth and another node  120 , 140 , 180 . The another node could be a AAA node or a Home Agent Database Node (HADN). 
         [0067]    The Access Node  170  stores at least one of message portion processing performance information  661  and message portion forwarding performance information  662  in message portion state  660 , regarding at least one previous message portion such as message portion  605  forwarded by said access node to one of the second and fourth nodes ( 120 , 140 ). The Access Node  170  can then select between the second node  120  and the fourth node  140  as a function of said stored performance information. This is useful because the forwarding or processing information state ( 661 , 662 ) can indicate excessive load or failures at one of said second and fourth nodes ( 120 , 140 ), and therefore direct subsequent message portions  605  towards the other of the second and fourth nodes ( 120 , 140 ) 
         [0068]    The MN  160  executes a retransmit timer  168  associated with said binding update message  603  and the MN is then operated to retransmit said binding update message  606  towards the second node  120  when the retransmit timer  168  expires prior to reception of a binding update response message  607  to said transmitted binding update message  603 . This enables the MN to undertake repeat attempts of the binding update via the second node  120 . Message portion  607  can include, in addition to the Mobile Node address  607   a , the forwarding address  607   b , non-addr information  607   c  such as security parameters, and 1 st  and second identifiers  607   d  and  607   e.    
         [0069]    One of the Access Node  170  and the MN  160  is operated to execute a second node transmission failure detection process ( 651 ,  167 ), respectively. When the failure detection process  651  indicates a transmission failure associated with said binding update message portion  605  that was transmitted to the second node then the access node  170  is operated to transmit a reselection message  604  to the MN  160  that includes a second/fourth node selection indicator  604   b  indicating that the fourth node is selected. The reception of this reselection message  604  or the indication of a transmission failure by the second node transmission failure detection process  167  in the MN  160 , causes the MN  160  to perform one of: retransmit said binding update message  606  including the MN address  606   a  towards the fourth node  140  and, transmit a new binding update message  606  to the fourth node  140 . The Access Node  170  is then operated to rereceive one of said new and retransmitted binding update messages  606  from the mobile node  160  including the MN address  161  in message part  606   a , a forwarding address  606   b , and an identifier of the fourth node  140  as the destination node identifier  606   c , said forwarding address having the value of one of forwarding addresses  171 , 171 ′, 162 ,  162 ′ that are used by said first node  110  to forward packets including said MN address  601 . 
         [0070]    The received and rereceived retransmitted binding update messages ( 603 , 606 ) include a first identifier ( 603   d , 606   d ), respectively. The Access Node  170  is operated to generate a message portion ( 605 , 608 ) from each of said received and rereceived retransmitted binding update messages ( 603 , 606 ), respectively, each of said message portions ( 605 , 608 ) further including a second identifier ( 605   c , 608   c ), respectively, the value of said second message identifiers ( 605   c , 608   c ) being different in each of said message portions ( 605 , 608 ), respectively, transmitted to the second node  120 . The second identifier is then used by subsequent nodes such as the first and second nodes ( 110 , 120 ) to distinguish between the message portion  605  and the retransmitted message portion  608 . The second identifiers ( 605   c , 608   c ) that are included in message portions ( 605 , 608 ) are optionally included in the received and rereceived retransmitted binding update messages ( 603 , 606 ) in message parts ( 603   e  and  606   e ), respectively. 
         [0071]    The received and rereceived retransmitted binding update messages ( 603 , 606 ) can include a first identifier ( 603   d , 606   d ), the value of the first identifiers in said messages ( 603 , 606 ), respectively, having the same value. One of the mobile node  160  and the access node  170  is then operated to generate a second identifier ( 605   c , 608   c ) that is included in the message portion ( 605 , 608 ) transmitted to each of said second and fourth nodes ( 120 , 140 ), the value of said second identifiers being different. This enables the value of the second identifier to be used to distinguish between the two message portions at upstream nodes such as the first node  110 . 
         [0072]    When the received and rereceived new binding update messages ( 603 , 606 ) include a first message identifier ( 603   d , 606   d ), and the value of the first identifiers in each of said messages ( 603   d , 606   d ) are different such that an upstream such as the first node  110  can distinguish between the messages using the first identifier values ( 603   d , 606   d ) only. 
         [0073]    The access node  170  may be, and sometimes is, operated to transmit a performance information message  609  to one of the second, fourth and another nodes ( 120 , 140 , 180 ) including performance information  609   a  corresponding to the stored performance information  661 , 662 . The access node  170  may further be operated to receive a message  620  including updated mapping information, said updated mapping information including at least one of a second node identifier  620   b  and a standby node identifier  620   c , said standby node identifier  620   c  corresponding to a standby node such as network node  192  to be used in place of said fourth node  140  with respect to processing of binding update messages  603  including said mobile node address  603   a.    
         [0074]      FIG. 7  illustrates in drawing  700  the exemplary nodes, state, signaling and methods of various novel embodiments from the perspective of the second and fourth nodes ( 120 , 140 ) wherein the second node  120  and then the fourth node  140  control the forwarding performed by the first node  110  and the third node  130  to the MN  160 .  FIG. 7  indicates forwarded packets  701  via the first node  110  and access node  170  including the MN address  161  and forwarded packets  702  via the third node  130  and access node  170  including the MN address  161 . It further indicates that the second and fourth nodes ( 120 , 140 ) include binding update signaling processes ( 126 , 146 ), respectively, which work together with binding update signaling processes ( 127 , 128 , 147 , 148 ) as shown in  FIGS. 5 and 6 , to perform the signaling of the embodiment at the second and fourth nodes ( 120 , 140 ), respectively. 
         [0075]    To manage such forwarding in a preferred scheme, the second node  120  sends a first message  703  to the first node  110  that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via the first node  110  and the access node  170 . Message  703  includes the similar fields as message  402 . The second node  120  then receives a change request message from the one of the first and third nodes ( 110 , 130 ) requesting that the second node  120  stop providing forwarding information using a subsequent message  703  to the first node  110  for packets including said mobile node address  161 . Exemplary change request message  704  from first node  110  to second node  120  is such a change request message. Message  704  includes the similar fields to those in message  405 . The fourth node  140  will then transmit the second message  705  that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via one of the first and third nodes ( 110 , 130 ) and the access node  170 . Message  705  includes the similar fields as message  450 . To enable the fourth node  140  to know that it needs to send the second message  705  to one of the first and third nodes ( 110 , 130 ), the second node  120  can transmit a changeover message  706  to one of the fourth node  140  and another node  180 . Message  706  includes similar fields to those in message  415 , as well as an identifier such as an address of at least one of the first and third nodes. In this example, the changeover message  706  is sent from the second node  120  to the fourth node  140 . The changeover message would indicate the change from the second node  120  to the fourth node  140 , and in the case of it being directed at the Another Node  180 , which could be the HA Database Node or a AAA node, then the Another Node  180  would propagate the changeover message to the fourth node  140 . In advance of operating the fourth node  140  to transmit the second message  705  to the first node, the second node  120  could alternatively receive a changeover message  707  from one of the fourth node  140  and another node  180 , said changeover message  707  indicating that the second node  120  is to stop providing forwarding information for the MN address  161  via message like message  703 , said changeover message  707  having been triggered by local state in the fourth or Another Node  140 , 180  or be triggered by reception of a message at the fourth or Another node  140 , 180  such as a change request message like  704  from one of the first and third nodes  110 , 130 . Message  707  includes similar fields to that in message  415 , as well as an identifier such as an address of the fourth node, and an identifier such as an address of at least one of the first and third nodes. In this example, changeover message  707  received by second node  120  is from the another node  180 . 
         [0076]    A second alternative scheme employs the first and second messages ( 703 , 704 ) but instead of one of the first and third nodes ( 110 , 130 ) sending a change request message  704  to request a change from the second node  120  to the fourth node  140 , the second node  120  instead receives a changeover message  707  from one of the fourth node  140  and another node  180 . The second node then optionally returns a changeover response message  708  to one of the first, third, fourth and another nodes ( 110 , 130 , 140 , 180 ), preferentially to the sender of the changeover message  707 . Message  708  includes similar fields to that included in message  415 . Alternatively, in advance of the step of operating the second node  120  to receive a changeover message  707  from one of the fourth node  140  and another node  180 , the fourth node  140  can be operated to receive a changeover message  709  from one of the first node  110 , third node  130 , second node  120  and another node  180 . Message  709  includes similar fields to that included in message  405 . 
         [0077]    A third alternative scheme employs the first message  703  from the second node  120  to the first node  110 , the second node  120  then receiving the changeover message  707 , followed by the fourth node transmitting a third message  710  to the third node  130  that includes third forwarding information, said third forwarding information  139  to be used for forwarding packets including said mobile node address  161  via the third node  130  and an access node  170 . Message  710  includes similar fields to that included in message  450 , but of course includes 3 rd  forwarding information. This means that the changeover of control from the second node  120  to the fourth node  140  includes a changeover of packet forwarding from the first node  110  to the third node  130 . In advance of the step of operating the second node  120  to receive a changeover message  707  from one of the fourth node  140  and another node  180 , the fourth node  140  receives a changeover message  709  from one of the first node  110  and the third node  130 . 
         [0078]    In a fourth alternative scheme, the second node  120  sends the first message  703  to the first node  110  that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address  161  via the first node  110 , in addition to an access node  170 . The second node  120  then receives a change request message  711  from one of the first node and third nodes  110 , 130  requesting that the second node  120  stop providing forwarding information to the first node  110  for packets including said mobile node address  161 . Message  711  includes message fields similar to message  405 . The fourth node  140  then transmits the third message  710  to the third node  130  that includes third forwarding information, said third forwarding information  139  to be used for forwarding packets including said mobile node address  161  via the third node  130  and an access node. In advance of the step of operating the fourth node  140  to transmit the third message  710  to the third node  130 , the second node  120  can optionally receive a changeover message  707  from one of the fourth node  140  and another node  180 . 
         [0079]    In each of the various exemplary schemes, the first and second ( 703 ,  705 ) or first and third forwarding messages ( 703 , 710 ) can include the same or different (ie a new Access Node) forwarding addresses for packets including the MN address  161 . 
         [0080]      FIG. 4  illustrates in drawing  400  exemplary nodes, state, signaling and methods of various embodiments from the perspective of the first node  110 . The first node  110  receives a first message  402  from the second node  120  which includes first forwarding information  402   a  associated with the MN  160  that is stored in the first node  110  in forwarding information  114 . Forwarding information  114  includes mobile node address  115  which would have the value of MN address  161  and forwarding address  116  which would have the value of forwarding address  162  and/or  171  from the MN  160  and AN  170  respectively. The forwarding information  114  enables packets that arrive at the first node  110  that are destined to the MN address  161  to be forwarded towards the forwarding address  116  as a forwarded packet  401 , said packet  401  including mobile node address  401   a , a CN address  401   b , and a payload  401   c.    
         [0081]    Some time later, the first node receives a second message  450  that is associated with the MN address  161 , and which includes second forwarding information  450   a . This is used to update forwarding information  114  in the first node  110 . The second forwarding information  450   a  can include the same forwarding address as the first forwarding information  402   a  or it can include a new forwarding address such as  171 ′ or  162 ′ as a result of a move by the MN to the Access node  170 ′. The forwarding address received in second message  450  is stored in the first node as forwarding address  116  so that forwarded packets including mobile node address  401   a  continue to be forwarded towards the MN  160 . The first node keeps track of which of the second and fourth nodes  120 ,  140  is providing forwarding information  402   a ,  450   a  by storing an identifier of the current provider of forwarding information as current provider identifier  118 . The identifier could be an address, name, location or some combination of these information types that is associated with the current provider, some portion of which is included in messages  405 , 410 , 415  and  420 . The first node  110  can also store a local provider preference to indicate which of the second and the fourth nodes  120 , 140  it would prefer to provide forwarding information. 
         [0082]    Before receiving the second message  450 , the first node  110  can transmit a change request message  405  to the second node  120 , requesting that the second node  120  no longer provide forwarding information such as forwarding information  402   a  to the first node  110 . Change request message  405  can optionally indicate that the first node  110  would like to receive forwarding information henceforth from the fourth node  140 . Change request message  410  can additionally or alternatively be sent to the fourth node  140  to request that the fourth node  140  start to provide forwarding information such as forwarding information  450   a  to the first node  110 . The change request message  410  can optionally indicate that the second node  120  is no longer to provide forwarding information to the first node  110  such as forwarding information  402   a . Change indication message  415  is sent from the second node  120  to the first node  110 . It can be sent in response to change request message  405  to indicate the result of the change request at the second node  120 . It can alternatively be received by the first node  110  without first sending change request message  405  to indicate that the second node  120  is no longer going to provide forwarding information  402   a  to the first node  110 , and can optionally include an indication that the fourth node  140  will instead be providing forwarding information such as  450   a  to the first node  110 . 
         [0083]    Change indication message  420  is sent from the fourth node  140  to the first node  110 . It can be sent in response to change request message  410  to indicate the result of the change request at the fourth node  140 . It can alternatively be received by the first node  110  without first sending change request message  410  to indicate that the fourth node  140  will instead be providing forwarding information such as  450   a  to the first node  110 , and can optionally include an indication that the second node  120  is no longer going to provide forwarding information  402   a  to the first node  110 . The current provider (CP) information is included in field  405   a , 410   a , 415   a  and  420   a  whilst the next provider (NP) information is included in field  405   b , 410   b , 415   b , 420   b  and the Previous Provider (PP) is included in field  405   c , 410   c , 415   c , 420   c . Change request and indication messages  405 ,  410 ,  415 , 420  can be specific to the MN address  161 , in which case they include MNA field ( 405   d ,  410   d ,  415   d ,  420   d ) or can be for one or more MNA prefixes (MNAPs) of such MN addresses at the first node  110  in which case they include at least one MNAP field ( 405   e ,  410   e ,  415   e ,  420   e ). The current, previous or next provider information, can instead be implied by the change type information (CTI) and the address of the provider node that has transmitted or is to receive the message, which is either the second or the fourth node  120 , 140 . The change type information enables the receiving node to know that the sender is requesting to be, or is now, the current, previous or next provider, and the change type field enables the sending node to request that the receiving node become the current, next or previous provider. 
         [0084]    Whilst the first node  110  is being provided with forwarding information by the second node  120 , then the first node  110  periodically, and/or in response to reception of messages such as the first message, can transmit the third message  460  to the second node  120  that includes forwarding status information  460   a  for at least one MN address such as MN address  161 . 
         [0085]    Whilst the first node  110  is being provided with forwarding information by the fourth node  140 , then the first node  110  periodically, and/or in response to reception of messages such as the second message, can transmit the third message  460  to the second node  120  that includes forwarding status information  470   a  for at least one MN address such as MN address  161 . Forwarding status information  460   a ,  470   a  is stored in the first node  110  as forwarding status information  119  and could include for example one of, the number of packets forwarded by the first node  110  for a MN address  161  since the last such third or fourth message was transmitted, and, the length of time since such a packet was forwarded by the first node  110 . Forwarding status information  119  could include information for each forwarding direction (from and to the MN  160 ) or it could be stored as a combination of both directions of forwarding. 
         [0086]    The first node needs to be able to distinguish between different messages that contain forwarding information, such as first and second messages  402 , 450  and to protect such messages from replay attacks. The MN  160  adds a first identifier into a message that updates its forwarding address  162 , 171  and which is then propagated through the Access Node  170  and the second node  120  into the first message  402  that is transmitted to the first node  110 . The first identifier can be generated by ID generation module  169  or it can be generated by the ID generation module  189  in the Another Node  180  and sent to the MN  160  in message  487 . Similarly the first identifier can be transmitted by the MN  160  in a message that is then propagated by the fourth node  140  into the second message  450  that is transmitted to the first node  110 . The value of the first identifier in the first and second messages  402   b , 450   b  can be the same. The first node can then select between the forwarding information carried in the first and second messages ( 402   a , 450   a ) by the order of reception or by the local provider preference state  117  that indicates a preference for the fourth node  140  over the second node  120 . Alternatively, the value of the first and second identifiers in the first and second messages ( 402   b , 450   b ) can be different. The first node can then compare the values in fields  402   b  and  450   b , using the first second and third identifier comparison function module  113 , and use the results of the comparison to indicate if the second message  450  contains newer forwarding information  450   a , and then updating the forwarding information  114  with the forwarding information  450   a  in the second message  450  if the indication is true. The first identifier generation modules  189  and  169  and the first second and third identifier comparison function module  113  could employ a first identifier that is a sequence number or a timer and the result of the comparison function  113  would be that the value of the first identifier  450   a  in the second message  450  is less than, greater than or equal to the value of the first identifier  402   a  in the first message  402 . When the first and second messages  402 , 450  contain different values of the first identifier, the second message  450  can be a restoration message that is transmitted via the fourth node  140  to the first node  110  when one of the second node  120  and the communications path between the second node  120  and the first node  110  has failed. This can be detected by the failure of the MN  110  to receive a response message, said response message being dependent on the reception of a response message  480  at the second node  120  that is transmitted by the first node  110 . This response message  480  can additionally be transmitted to the fourth node  140  in response to the second message  450 . The response message  480  can include the first identifier  480   a , the value of the first identifier  480   a  in the response message  480  being the same as the value ( 402   b , 450   b ) received in the one of the first and second messages ( 402 , 450 ), respectively, to which the response message  480  is a response. Alternatively, the value of the first identifier  480   a  in the response message  480  can be different to the value of the first identifier ( 402   b , 450   b ) in one of the first and second messages ( 402 , 450 ) to which the response message  480  is a response, and is instead generated as a function of said first identifier ( 402   b , 450   b ) using response identifier generation function module  112 , which can optionally be a security function that also uses a security key that is shared with the generator module ( 169 , 189 ) that generated the value of the first identifier. This security processing ensures that the value of the first identifier  480   a  in the response message  480  is not easy to be produced by a node other than the first node  110 . 
         [0087]    When the values of the first identifier ( 402   b , 450   b ) in the first and second messages ( 402 , 450 ) are the same, then the order of generation of the forwarding information ( 402   a , 450   a ) in the first and second messages is unknown. In this case, the first message  402  can optionally include a second identifier  402   c . The second identifier is transmitted to the second node  120  by one of the MN  160  and the Access Node  170 . The second identifier can also be included in the second message  450  from the fourth node  140 . The first node  110  can then order forwarding information ( 402   a , 450   a ) that is received in the first and the second messages ( 402 , 450 ), respectively, so that at least a first repeat transmission of said forwarding information will be distinguished from a previous reception of said same forwarding information at the first node in the event that multiple copies of said forwarding information are transmitted, and then operating the first node to ignore the second message. 
         [0088]    Alternatively, when the values of the first identifier ( 402   b , 450   b ) in the first and second messages ( 402 , 450 ), respectively, are the same, then the first and second messages ( 402 , 450 ) can include the second identifiers ( 402   c , 450   c ) and third identifiers ( 402   d , 450   d ). The value of the third identifier is then an identifier generated by one of the second, fourth and another nodes ( 120 , 140 , 180 ) by identifier generator function modules ( 129 , 149 , 189 ), respectively. When the third identifier is generated in the another node  180 , then it is transmitted to one of the second and fourth nodes by another node  180  using message  485 . The first node  110  is then operated to compare the value of the second and third identifiers that are received in the first and second messages  402 , 450  to determine if the second message  450  contains new forwarding information corresponding to the mobile node address, new forwarding information being identified by said values of the third identifier  402   d , 450   d  being the same and the value of the second identifier in the second message  450   c  having been generated after the value of the second identifier  402   c  in the first message. The first node can then update the forwarding information  114  with the forwarding information  450   a  received in the second message. 
         [0089]    Instead of the second identifier  402   c  being received from the MN  160  or Access Node  170 , it can alternatively be generated by the second node  120  in identifier generation function module  129 , and, transmitted to the second node  120  by Another Node  180  in message  486 . In this case it is used to identify between repeat transmissions by the second node  120  to the first node  110 , of the same version of forwarding state (ie the same value of the first identifier  402   b  that was received from the MN  160  and/or Access Node  170 . 
         [0090]    When the values of the first identifier ( 402   b , 450   b ) in the first and second messages ( 402 , 450 ) are the same, and the first and second messages further include the third identifier ( 402   d , 450   d ), then the first node  110  can be operated to compare the value of the third identifiers ( 402   d , 450   d ) received in the first and second messages ( 402 , 450 ) to determine if new forwarding information  450   a  corresponding to the mobile node address  161  has been received, said values of the third identifier being different when new forwarding information has been received. The newest forwarding information can be identified by the first second and third identifier comparison function module  113  determining which of the third identifiers ( 402   d , 450   d ) were generated last. If the values of the third identifiers are the same then one of the order of reception and the local preference state will indicate that the forwarding state  450   a  in the second message will be stored in the forwarding state  114 . Note that when the value of the third identifiers ( 402   d , 450   d ) are the same, but the first second and third identifier comparison function indicates that the value of the first identifiers ( 402   b , 450   b ) are different then the second message  450  includes new forwarding information  450   a  if the value of the first identifier  450   b  in the second message  450  was generated after the value  402   b  in the first message  402 . 
         [0091]    The third identifiers ( 402   d , 450   d ) can be transmitted by one of the MN  160  and the Access Node  170  towards the second and fourth nodes ( 120 , 140 ). The third identifiers ( 402   d , 450   d ) can include a portion that contains one of a priority indication, a sequence number and a timer value, said priority indication affecting the local provider preference state  117 . When the values of third identifiers ( 402   d , 450   d ) are the same, as well as using the reception order of the first and second messages ( 402 , 450 ) or the local provider preference  117 , the first and second messages can further include a second identifier ( 402   c , 450   c ) that is used to order repeat transmissions of forwarding information. The first node  110  is then operated to compare the values of the second identifiers ( 402   c , 450   c ) in the first and second messages ( 402 ,  450 ), to order received forwarding information. The second message  450  can further include a primary indicator  450   e  such that the first node  110  can be operated to update forwarding information for the mobile node address  161  using the forwarding information  450   a  if the primary indicator is set to primary, indicating that the fourth node  140  is now the current provider of forwarding information. The response message  480  to the first message  402  can include the value of the third identifier  480   c  that was received in the first message  402   d . The response message  480  to the second message  450  can include the value of the third identifier  480   c  that was received in the second message  450   d . The first node can transmit a response message  480  to one of the second and fourth nodes ( 120 , 140 ) and include the third identifier  480   c , the value of the third identifier this time being different to the value of the third identifier that was received in the message ( 402 , 450 ) which is being responded to. 
         [0092]      FIG. 8  shows an exemplary Home Agent Database (HAD)  801  which can be located in the second node  120 , fourth node  140  or in the Another node  180  (HADN), or distributed between these nodes. The database  801  ensures that there is a single repository of system configuration information and of MN binding information so that either the second node  120  or the fourth node  140  can interact with the first node  110 , third node  130 , MN  160  and Access Node  170  to perform mobility management according to novel features of an exemplary embodiment. In a preferred implementation, the HADN is at the Another Node  180  or a number of such Another Nodes, with local copies of parts of that database kept in the second node  120  and fourth nodes  140 . The HAD  801  includes Access Node state  802 , HACN state  810 , HATN state  820 , and Mobile Node address state  850 . Access Node state  802  includes configuration information ( 803 , 806 ) of the Access nodes in the network  100  such as Access Node ( 170 , 170 ′). Access node state ( 803 ,  806 ), corresponding to access nodes ( 170 ,  170 ′) includes their IP and/or link-layer addresses ( 804 , 807 ) and the security parameters ( 805 ,  808 ), respectively, used to secure communications. HACN state  810  includes information  811  on the HACN  120  and information  815  on HACN  140 . HACN state information ( 811 ,  815 ) corresponding to nodes ( 120 ,  140 ) includes IP and/or link-layers addresses ( 812 , 816 ) and security parameters ( 813 , 817 ), respectively. HATN state  820  includes information  821  on HATN  820  and information  825  on HATN  130 . HATN state information ( 821 ,  825 ) corresponding to nodes ( 110 ,  130 ) includes IP and/or link-layer addresses ( 822 , 826 ) and security parameters ( 823 , 827 ), respectively. Mobile Node address state  850  includes information  851  on MN address  161 , and information  870  on at least one other MN address. Mobile node address state information  850  also includes HATN changeover signaling state  880  and HACN changeover signaling state  890 . Information  851  includes the MN identifier  852  that is using said MN address  161  and the MN security parameters  853 . It further includes an indication of the primary HATN  854 , an indicator of the secondary HATN  855 , an indicator of the current access node  856  and the forwarding address at that access node  857 . State information  851  also includes primary HACN state information  858  and secondary HACN state information  862 . HATN and HACN state ( 854 , 855 , 858  and  862 ) within Information  851  that is associated with Mn address  161  can instead be stored for one or more address prefixes, rather than for each individual address as shown in  FIG. 8 . The primary HACN state and the secondary HACN state ( 858 , 862 ) includes the HACN address ( 859 , 863 ), the HACN priority ( 860 , 864 ) and the performance information ( 861 , 865 ) associated with that HACN such as signaling and loading performance and current status (active/failed etc), respectively. The HATN changeover signaling state  880  may be stored for each MN address or for an aggregate of such addresses such as an address prefix. The changeover signaling state  880  tracks the status of the changeover from one HATN to another, or the addition or removal of a HATN as part of the use of two concurrent HATNs. HATN changeover signaling state  880  includes signaling progress state  881 , old HATN status  882  and new HATN status  883 . The changeover signaling progress state  881  tracks the progress of the changeover signaling message exchanges whilst Old HATN and New HATN status ( 882 , 883 ) tracks the consequences of that signaling progress on the forwarding at each HATN. Similarly, the HACN changeover signaling state  890  may be stored for each MN address or for an aggregate of such addresses such as an address prefix. The changeover signaling state  890  tracks the status of the changeover from one HACN to another, or the addition or removal of a HACN as part of the use of two concurrent HACNs. HACN changeover signaling state  890  includes signaling progress state  891 , old HACN status  892  and new HACN status  893 . The changeover signaling progress state  891  tracks the progress of the changeover signalling message exchanges whilst Old HACN and New HACN status ( 892 , 893 ) tracks the consequences of that signaling progress on the control of binding updates at each HACN. 
         [0093]      FIG. 9  is a drawing of an exemplary state diagram  900  for an exemplary tunneling agent (TA) node in accordance with various embodiments. A tunneling agent node may be, and sometimes is, alternatively referred to as a home agent tunneling node. A distributed home agent node (DHA) node may be, and sometimes is, alternatively referred to as a home agent control node (HACN). The various states include an inactive state  902 , an active state  904 , an enabled state  906 , a disabled state  908  and an obsolete state  910 . The TA transitions from an inactive state  902  to an active state  904  to forward a packet for the MN address as represented by arrow  912 . The TA transitions from an inactivate state  902  to an enabled state  906  in response to the TA losing current binding on expiry/deletion as indicated by arrow  916 . 
         [0094]    The TA transitions from active state  904  to inactive state  902 , as represented by arrow  914 , if the TA has not forwarded a packet for the MN address during an interval of time, e.g., an interval of time represented by an inactivity jimer variable value. The TA transitions from an active state  904  to an enabled state  906 , as indicated by arrow  920 , in response to the TA losing current binding on expiry/deletion. 
         [0095]    The TA transitions from the enabled state  906  to the inactive state  902 , as indicated by arrow  918 , in response to the TA acquiring current binding for the MN address. The TA transitions from the enabled state  906  to the disabled state  908 , as indicated by arrow  922 , in response to the TA determining that it is not a next hop for the MN address. 
         [0096]    The TA transitions from the disabled state  908  to the enabled state  906 , as indicated by arrow  924 , in response to the TA determining that it is a next hop for the MN address. The TA transitions from the disabled state  908  to the obsolete state  910 , as indicated by arrow  926 , in response to the TA deciding to cease to inject the MN address into the IGP. The TA transitions from the obsolete state  910  to the disabled state  908 , as indicated by arrow  928 , in response to the TA deciding to inject the MN address into the IGP. 
         [0097]      FIG. 10  is a drawing of an exemplary state diagram  1000  for an exemplary tunneling agent (TA) node in accordance with various embodiments. A tunneling agent node may be, and sometimes is, alternatively referred to as a home agent tunneling node. A distributed home agent (DHA) node may be, and sometimes is, alternatively referred to as a home agent control node (HACN). The various states include an inactive state  1002 , an active state  1008 , an active expiry due state  1010 , a binding pending state  1006 , an inactive expiry due state  1004 , an active binding delete state  1014 , an enabled with backlog state  1012 , an enabled state  1020 , a just enabled state  1016 , an inactive binding delete state  1018 , a disabled state  1022  and an obsolete state  1024 . The TA transitions from an inactive state  1002  to an active state  1008  to forward a packet for the MN address as represented by arrow  1028 . The TA transitions from an inactivate state  1002  to an inactive binding delete state  1018 , as indicated by arrow  1058 , in response to a binding deletion message received from a DHA. The TA transitions from the inactive binding delete state  1018  to the enabled state  1020 , as indicated by arrow  1066 , in response to implementation of the binding deletion and sending of a response message to the DHA. 
         [0098]    The TA transitions from the inactive state  1002  to the inactive expiry due state  1004 , as indicated by arrow  1030 , in response to a binding slow update timer having expired. The TA transitions from the inactivity expiry due state  1004  to the binding pending state  1006 , as indicated by arrow  1036 , in response to the TA deciding to send an On demand slow binding request to the DHA. Arrow  1038  indicates that the TA remains in the binding pending state while the reply timer has not expired and a reply does not occur. The TA transitions from the binding pending state  1006  to the inactive state  1002 , as indicated by arrow  1032 , in response to an On demand fast binding reply being received with a new binding. 
         [0099]    The TA transitions from the active state  1008  to the inactive state  1002 , as indicated by arrow  1026 , in response to the TA not having forwarded a packet for the MN address during a time interval, e.g., the time interval represented by the value of the variable inactivity_timer. The TA transitions from the active state  1008  to the active binding delete state  1014 , as indicated by arrow  1050 , in response to the TA receiving a binding deletion message from the DHA. The TA transitions from the active state to the active expiry due state  1010 , as indicated by arrow  1048 , in response to the binding fast update timer having expired. The TA transitions from the active expiry due state  1010  to the binding pending state  1006 , as indicated by arrow  1046 , in response to a decision to send an on demand fast binding request to the DHA. The TA transitions from the binding pending state  1006  to the active state, as indicated by arrow  1040 , in response to an On demand slow binding reply being received with a new binding. 
         [0100]    The TA transitions from the active binding delete state  1014  to the enabled with backlog state  1012 , as indicated by arrow  1052 , in response to the binding deletion being performed and a response message being sent to the DHA. The TA transitions from the enabled with backlog state  1012  to the binding pending state  1006 , as indicated by arrow  1044 , in response to an On demand binding request being sent to the DHA. The TA transitions from the binding pending state  1006  to the enabled with backlog state  1012 , as indicated by arrow  1042 , in response to an on demand binding reply being received without a binding or no reply being received before the lifetime expiry. 
         [0101]    The TA transitions from the enabled with backlog state  1012  to the enabled state  1020 , as indicated by arrow  1054 , in response to a packet including MN address being discarded. The TA transitions from the enabled state  1020  to the enabled with backlog state  1012 , as indicated by arrow  1056 , in response to a packet including MN address being received. The TA transitions from the enabled state  1020  to the inactive state  1002 , as indicated by arrow  1060 , in response to the TA receiving a proactive binding from the DHA and sending a reply. 
         [0102]    The TA transitions from the enabled state  1020  to the disabled state  1022 , as indicated by arrow  1068 , in response to the TA determining that it is not a next hop for the MN address. The TA transitions from the disabled state  1022  to the enabled state  1020 , as indicated by arrow  1070 , in response to the TA determining that it is a next hop for the MN address. The TA transitions from the disabled state  1022  to the obsolete state  1024 , as indicated by arrow  1072 , in response to the TA deciding not to inject the MN address into the IGP. The TA transitions from the obsolete state  1024  to the disabled state  1022 , as indicated by arrow  1074 , in response to the TA deciding to inject the MN address into the IGP. 
         [0103]      FIG. 11  is flowchart  1100  of an exemplary method of operating an access node in accordance with various embodiments. The exemplary method is a method for use in a communications system including the access node, a first node, e.g., a first HATN, a second node, e.g., a first HACN, and a fourth node, e.g., a second HACN. In various embodiments, the communications system also includes another node, which communicates with the access node as part of the exemplary method. 
         [0104]    Operation starts in step  1102 , where the access node is powered on and initialized. Operation proceeds from start step  1102  to step  1104 . In step  1104  the access node stores information indicating a mapping between an MN address and identifiers of the second node and the fourth node. Then, in step  1106 , the access node receives a binding update message including the MN address and a forwarding address, the forwarding address being used by the first node to forward a portion of the binding update message to the second node. In various embodiments, the received binding update message includes a first identifier. Operation proceeds from step  1106  to step  1108 . 
         [0105]    In various embodiments, the forwarding address is an address of the access node and the access node includes a Mobile IP foreign agent. In some embodiments, the second and fourth nodes are nodes which process binding update signaling for a binding between a mobile node address and a forwarding address used by the first node to forward packets including said mobile node address. 
         [0106]    In step  1108  the access node selects between the second and fourth nodes as the destination of a portion of the binding update message. In various embodiments, the selection of step  1108  is based on at least some information included in said binding update message. In some such embodiments, the at least some information including in the binding update message is non-address information. 
         [0107]    In some embodiments, the access node selects between the second and fourth nodes based on a priority indicator included in the stored mapping information. For example, the access node makes the selection and selects the second node rather than the fourth node as the destination for the message based on a priority indicator included in said stored mapping information, said priority indicator being associated with at least one of the second and fourth nodes, said priority indicator indicating that the second node has priority over the fourth node. 
         [0108]    In some embodiments, the access node stores at least one of message portion processing performance information and message portion forwarding performance information regarding at least one previous message portion forwarded by said access node to one of the second and fourth nodes, and the selecting selects as a function of the stored performance information. For example, the access node selects the second node rather than the fourth node as the destination for the message portion as a function of the stored performance information. 
         [0109]    Depending upon the selection of step  1108 , operation proceeds from step  1108  to either step  1110  if the second node was selected or step  1111  if the fourth node was selected. In step  1110  the access node forwards said portion of said binding update message to the second node. In step  1111  the access node forwards said portion of said binding update message to the fourth node. 
         [0110]    Operation proceeds from step  1110  to one or more of steps  1112 ,  1122  and  1134 . In step  1112  the access node operates a retransmit timer associated with the forwarded portion of the binding update message. Then, in step  1114 , the access terminal checks as to whether the retransmit timer has expired prior to a reception of a response to the forwarding of said message portion. If the timer has not expired and a response has not been received, operation returns to the input of step  1114 . However, if the timer expires without reception of a response, then operation proceeds from step  1114  to step  1116 . 
         [0111]    In step  1116  the access terminal adds a second identifier to said transmitted message portion. In various embodiments, the forwarded portion of the binding update message of step  1110  was also transmitted with a second identifier; however, the value of the second identifier of step  1110  is different than the value of second identifier of steps  1116  and  1118 . Thus the value of the second identifier, in some embodiments, is different depending upon whether the portion of the binding message being communicated is being transmitted as an initial transmission or as a retransmission, e.g., a retransmission following a timeout expiration. Then, in step  1118  the access terminal transmits said portion of said binding update message with said added second identifier from step  1116  to said second node. Step  1118  includes sub-step  1120  which is the retransmission of said portion of said binding update message to said second node. 
         [0112]    Operation proceeds from step  1118  to step  1121  in which the access terminal receives a message including updated mapping information that includes priority information that includes changes in priority indication information corresponding to at least one of the second and fourth nodes. In some embodiments, the received message including updated mapping information of step  1121  was transmitted by one of: the second node, the fourth node and the another node. 
         [0113]    Returning to step  1122 , in step  1122  the access node operates to execute a second node transmission failure detection process. In step  1124  the access node proceeds differently depending upon whether or not the access node transmission failure process indicates a failed transmission. If a failed transmission is not indicated, then the access node need not take any corrective action. However, if the access node transmission failure process indicates a failed transmission, then operation proceeds from step  1124  to step  1126 . 
         [0114]    In step  1126 , the access node adds a second identifier to said portion of said binding update message. In various embodiments, the forwarded portion of the binding update message of step  1110  was also transmitted with a second identifier; however, the value of the second identifier of step  1110  is different than the value of second identifier of steps  1126  and  1128 . For instance, the first node, e.g., tunneling agent node, can discriminate between two messages by the second identification value. In various other embodiments, the forwarded portion of the binding update message of step  1110  was also transmitted with a second identifier; however, the value of the second identifier of step  1110  is the same as the value of second identifier of steps  1126  and  1128 . For instance the first node, e.g., tunneling agent node, can discriminate between two messages because they come via different HACNs. 
         [0115]    Then in step  1128 , the access node transmits said portion of said binding update message and said second identifier from step  1126  to the fourth node. Step  1128  includes sub-step  1130  in which the access node transmits said portion of said binding update message to said fourth node. 
         [0116]    Returning to step  1134 , in step  1134  the access terminal transmits a message to one of the second node, fourth node and another node, said transmitted message including performance information corresponding to stored performance information. Operation proceeds from step  1134  to step  1136 . In step  1136  the access node receives a message including updated mapping information, said updated mapping information including at least one of a second node identifier and a standby node identifier corresponding to a standby node to be used in place of said fourth node with respect to processing of binding update messages including said mobile node address. 
         [0117]      FIG. 12  is a flowchart  1200  of an exemplary method of operating a communications system in accordance with various embodiments. The exemplary communications system includes a first node, e.g., a first home agent tunneling node (HATN), a second node, e.g., a first home agent control node (HACN), a third node, e.g., a second home agent tunneling node (HATN), a fourth node, e.g., a second home agent control node (HACN), and an access node. In various embodiments, the communications system also includes another node which is involved in the exemplary method. 
         [0118]    Operation of the exemplary method starts in step  1202 , where the various nodes of the system are powered on and initialized and proceeds to step  1204 . In step  1204 , the second node, is operated to send a first message to the first node that includes first forwarding information to be used for forwarding packets including a mobile node address via one of the first node, and the third node, in addition to an access node. Operation proceeds from step  1204  to step  1206 . In step  1206 , the second node is operated to receives a change request message from the first node requesting that the second node stop providing forwarding information to the first node for packets including said mobile node address. 
         [0119]    Operation proceeds from step  1206  to step  1208  or to alternative step  1210 . In step  1208  the second node is operated to transmit a changeover request message to one of the fourth node and the another node. In step  1210  the second node is operated to receive a changeover message from one of the fourth node and another node. Operation proceeds from step  1208  or step  1210  to step  1212 . 
         [0120]    In step  1212  the fourth node is operated to transmit a second message to the first node that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and an access node. In various embodiments, the first and second forwarding information includes the same forwarding address. 
         [0121]      FIG. 13  is a flowchart  1300  of an exemplary method of operating a communications system in accordance with various embodiments. The exemplary communications system includes a first node, e.g., a first home agent tunneling node (HATN) node, a second node, e.g., a first home agent control node (HACN), a third node, e.g., a second home agent tunneling node (HATN), a fourth node, e.g., a second home agent control node (HACN) node, an access node, and another node (HADN). 
         [0122]    Operation of the exemplary method starts in step  1302 , where the various nodes of the system are powered on and initialized and proceeds to step  1304 . In step  1304 , the second node, is operated to send a first message to the first node that includes first forwarding information to be used for forwarding packets including a mobile node address via one of the first node and the third node, in addition to an access node. Operation proceeds from step  1304  to step  1306 . In step  1306 , the fourth node is operated to receive a changeover message from one of the first node, the second node and the another node (HADN). 
         [0123]    Operation proceeds from step  1306  to step  1308 . In step  1308  the second node is operated to receive a changeover message from one of the fourth node and the another node. Operation proceeds from step  1308  to step  1310 . In step  1310  the second node is operated to transmit a changeover response message to one of the first node, the fourth node and the another node. 
         [0124]    Operation proceeds from step  1310  to step  1312 . Instep  1312  the fourth node is operated to transmit a second message to the first node that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and an access node. In various embodiments, the first and second forwarding information includes different forwarding addresses. 
         [0125]      FIG. 14  is a flowchart  1400  of an exemplary method of operating a communications system in accordance with various embodiments. The exemplary communications system includes a first node, e.g., a first home agent tunneling node (HATN) node, a second node, e.g., a first home agent control node (HACN) node, a third node, e.g., a second home agent tunneling node (HATN), a fourth node, e.g., a second home agent control node (HACN), an access node, and another node (HADN). 
         [0126]    Operation of the exemplary method starts in step  1402 , where the various nodes of the system are powered on and initialized and proceeds to step  1404 . In step  1404 , the second node, is operated to send a first message to the first node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via one of the first node and the third node, in addition to an access node. Operation proceeds from step  1404  to step  1406 . In step  1406 , the fourth node is operated to receive a changeover message from one of the first node, the third node and the another node. 
         [0127]    Operation proceeds from step  1406  to step  1408 . In step  1408  the second node is operated to receive a changeover message from one of the fourth node and the another node. Operation proceeds from step  1408  to step  1410 . In step  1410  the second node is operated to transmit a changeover response message to one of the first node, the fourth node and the another node. 
         [0128]    Operation proceeds from step  1410  to step  1412 . In step  1412  the fourth node is operated to transmit a third message to the third node that includes third forwarding information, said third forwarding information to be used for forwarding packets including said mobile node address via the third node and access node. 
         [0129]      FIG. 15  is a flowchart  1500  of an exemplary method of operating a communications system in accordance with various embodiments. The exemplary communications system includes a first node, e.g., a first home agent tunneling node (HATN), a second node, e.g., a first home agent control node(HACN), a third node, e.g., a second home agent tunneling node (TA), a fourth node, e.g., a second home agent control node (HACN), and an access node. In various embodiments, the communications system also includes another node (HADN) which is involved in the exemplary method. 
         [0130]    Operation of the exemplary method starts in step  1502 , where the various nodes are powered on and initialized and proceeds to step  1504 . In step  1504 , the second node is operated to send a first message to the first node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via one of the first node and the third node, in addition to an access node. Operation proceeds from step  1504  to step  1506 . 
         [0131]    In step  1506 , the second node is operated to receive a change request message from one of the first node and the third node requesting that the second node stop providing forwarding information to the first node for packets including said mobile node address. Operation proceeds from step  1506  to step  1508 . 
         [0132]    In step  1508  the second node is operated to receive a changeover message from one of the fourth node and the another node. Operation proceeds from step  1508  to step  1510 . In step  1510  the fourth node is operated to transmit a third message to the third node that includes third forwarding information, said third forwarding information to be used for forwarding packets including said mobile node address via the third node and an access node. 
         [0133]      FIG. 16  is a flowchart  1600  of an exemplary method of operating a communications system in accordance with various embodiments. The exemplary communications system includes a first node, e.g., a first home agent tunneling node (HATN), a second node, e.g., a first home agent control node (HACN), a fourth node, e.g., a second home agent control node (HACN), and an access node, e.g., an access node including a mobile IP foreign agent. Operation of the exemplary method starts in step  1602  where the nodes are powered on and initialized and proceeds to step  1604 . 
         [0134]    In step  1604  the first node is operated to receive a first message from the second node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via the first node and an access node. 
         [0135]    Then in step  1566  the first node is operated to store information including an identifier of the second node, said identifier indicating that the second node is a current provider of forwarding information for packets including the MN address. Operation proceeds from step  1606  to step  1608 . 
         [0136]    In step  1608  the first node is operated to receive a second message from the fourth node that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and the access node. In some embodiments, the first forwarding information is a first binding between the mobile node address and a forwarding address and the second forwarding information is a second binding between the mobile node address and the same forwarding address. In some other embodiments, the first forwarding information is a first binding between the mobile node address and a forwarding address and the second forwarding information is a second binding between the mobile node address and a different forwarding address. 
         [0137]    Then, in step  1610  the first node is operated to store information including an identifier indicating that the fourth node is the current provider of forwarding information for packets including the MN address. In various embodiments, step  1610  includes one of sub-steps  1612 ,  1614  and  1616 . 
         [0138]    In some embodiments, the second message includes a flag used to indicate one of a primary and secondary node status. In sub-step  1612  the first node is operated to store information indicating that the fourth node is the current provider of forwarding information for packets including the MN address since a flag in the second message indicated that the fourth node is the primary node. 
         [0139]    In some embodiments, the first node maintains information indicating which one of the second and fourth nodes is the current provider of forwarding information for packets including the MN address. In sub-step  1616 , the first node is operated to store information indicating that fourth node is the current provider of forwarding information for packets including the MN address since the second message from the fourth node is the most recently received message, e.g., more recent than the first message from the second node. In sub-step  1616 , the first node is operated to store information indicating that the fourth node is the current provider of forwarding information since the first node has local preference state indicating a preference for the fourth node over the second node for providing forwarding information. 
         [0140]    Operation proceeds from step  1610  to step  1618 . In step  1618  the first node is operated to transmit a third message to the second node providing forwarding status information regarding forwarding performed by the first node for packets included in the MN address. Operation proceeds from step  1618  to step  1620 . In step  1620  the first node is operated to transmit a fourth message to the fourth node providing forwarding status information regarding forwarding performed by the first node for packets including the MN address. 
         [0141]      FIG. 17  is a flowchart  1700  of an exemplary method of operating a communications system in accordance with various embodiments. The exemplary communications system includes a first node, e.g., a first home agent tunneling node (HATN), a second node, e.g., a first home agent control node (HACN), a third node, e.g., a second home agent tunneling node (HATN), a fourth node, e.g., a second home agent control node(HACN), and an access node. In various embodiments, the communications system also includes another node (HADN) which is involved in the exemplary method. 
         [0142]    Operation of the exemplary method starts in step  1702 , where the various nodes are powered on and initialized and proceeds to step  1704 . In step  1704 , the first node is operated to receive a first message from the second node that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via the first node and an access node. Operation proceeds from step  1704  to one or more of steps  1706 ,  1708 ,  1710  and  1720 . 
         [0143]    In step  1706  the first node is operated to transmit a change request message to the second node requesting that the second node stop providing forwarding information to the first node for packing including said mobile node address. In step  1708  the first node is operated to transmit a change request message to the fourth node requesting that the fourth node provide forwarding information for forwarding packets including said mobile node address via the access node. In step  1710  the first node is operated to receive a change indicator message from the fourth node indicating a changeover to the fourth node, said change indicator message including information to be used by the first node for forwarding packets including said mobile node address via said access node. In step  1712  the first node is operated to receive a change indication message from the second node indicating a changeover to the fourth node, said changeover resulting in at least one message that includes information to be used by the first node for forwarding packets including said mobile node address via the access node being transmitted from the fourth node to the first node. 
         [0144]    Operation proceeds from one or more of steps  1706 ,  1708 ,  1710  and  1712  to step  1714 . In step  1714 , the first node is operated to receive a second message from the fourth node that includes second forwarding information, said second forwarding information to be used for forwarding packets including said mobile node address via the first node and the access node. 
         [0145]      FIG. 18  is a drawing of an exemplary communications system  1800  in accordance with various embodiments. Exemplary communications system  1800  includes a second node  1802 , e.g., a first home agent control node (HACN), a fourth node  1804 , e.g., a second home agent control node (HACN), a first node  1806 , e.g., a first home agent tunneling node (HATN), a third node  1808 , e.g., a second home agent tunneling node (HATN), an another node  1810 , e.g., a home agent database node (HADN), a plurality of access nodes (access node  1   1812 , . . . , access node N  1814 ), and a plurality of wireless terminals (WT  1   1816 , e.g., MN  1 , . . . , WT M  1818 , e.g., MN M). The second node  1802 , fourth node  1804 , first node  1806 , third node  1808 , another node  1810 , and access nodes ( 1812 , . . . ,  1814 ) are coupled together via a backhaul network. The wireless terminals ( 1816 , . . . ,  1818 ) may be, and sometimes are, coupled to an access node ( 1812 , . . . ,  1814 ) via a wireless link. In some embodiments, nodes ( 1802 ,  1804 ,  1806 ,  1808 ,  1810 ,  1812 ,  1814 ,  1816 ,  1818 ) are nodes ( 120 ,  140 ,  110 ,  130 ,  180 ,  170 ,  170 ′,  160 ,  150 ), respectively, described with respect to other figures. 
         [0146]    Second node  1802  includes a processor  1820 , an I/O interface  1822  and memory  1824  coupled together via a bus  1821  over which the various elements may interchange data and information. Memory  1824  includes routines  1826  and data/information  1828 . The processor  1820 , e.g., a CPU, executes the routines  1826  and uses the data/information  1828  in memory  1824  to control the operation of the second network node  1802  and implement methods, e.g., a portion of a method of flowchart  1200  of  FIG. 12  and/or a portion of a method described with respect to  FIG. 7 . Routines  1826  include a first message module  1830 , a change request processing module  1832 , a changeover message module  1834  and a changeover message processing module  1836 . 
         [0147]    I/O interface  1822  couples the second network node  1802  to other network nodes and/or the Internet. Messages are exchanged between node  1802  and other network nodes via I/O interface  1822 . First message processing module  1830  is for generating and sending a first message to the first network node  1806 , e.g., first HATN, wherein the first message includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via one of the first network node  1806 , e.g., first HATN, and the third network node  1808 , e.g., second HATN, in addition to an access node, e.g., node  1812 . The first message is, e.g., a first forwarding information message from the first HACN  1802  to the first HATN  1806 . Change request processing module  1832  is for processing a received change request message from the first node  1806 , e.g., first HATN) requesting that the second node  1802 , e.g., first HACN, stop providing forwarding information to the first network node  1806 , e.g., first HATN, for packets including a mobile node address. Changeover message module  1834  is for generating and sending a changeover message to one of the fourth node  1804 , e.g., second HACN, and the another node  1810 , e.g., HADN, prior to the fourth node  1804  sending the second message to the first node  1806 . Changeover message processing module  1836  is processing a changeover message from one of the fourth node  1804 , e.g., second HACN, and the another node  1810 , e.g. HADN, prior to the fourth node transmitting the second message to the first node  1806 . 
         [0148]    Fourth node  1804  includes a processor  1838 , an I/O interface  1840  and memory  1842  coupled together via a bus  1844  over which the various elements may interchange data and information. Memory  1842  includes routines  1846  and data/information  1848 . The processor  1840 , e.g., a CPU, executes the routines  1846  and uses the data/information  1848  in memory  1842  to control the operation of the fourth network node  1804  and implement methods, e.g., a portion of a method of flowchart  1200  of  FIG. 12  and/or a portion of a method described with respect to  FIG. 7 . Routines  1426  include a second message module  1850 . 
         [0149]    I/O interface  1840  couples the second network node  1804  to other network nodes and/or the Internet. Messages are exchanged between node  1804  and other network nodes via I/O interface  1840 . Second message processing module  1850  is for generating and sending a second forwarding information message to the first network node  1806 , e.g., first HATN, wherein the second forwarding information message includes second forwarding information, said second forwarding information to be used for forwarding packets includes a mobile node address via the first node  1808 , e.g., first HATN, and an access node. The second forwarding information message is, e.g., a message from the fourth node  1804 , e.g., second HACN, to the first HATN  1806 . 
         [0150]      FIG. 19  is drawing of an exemplary first node  1900 , e.g., an exemplary first home agent tunneling node, in accordance with various embodiments. Exemplary first node  1900  is for use in a communications system including first node  1900 , a second node, e.g., a first HACN, a fourth node, e.g., a second HACN, and an access node. First node  1900  is, in some embodiments, first node  110  described with respect to other figures. 
         [0151]    First node  1900 , e.g., a first home agent tunneling node, includes a processor  1902 , an I/O interface  1904  and memory  1906  coupled together via a bus  1908  over which the various elements may interchange data and information. I/O interface  1904  couples the first node  1900  to other network nodes, e.g. a first HACN, a second HACN, an access node, and another node, e.g., a HADN, via which the first node can send and receive messages. 
         [0152]    Memory  1906  includes routines  1910  and data/information  1912 . The processor  1902 , e.g., a CPU, executes the routines  1910  and uses the data/information  1912  in memory  1906  to control the operation of the first node  1900  and implement methods, e.g., a method in accordance with flowchart  1600  of  FIG. 16  or a method in accordance with flowchart  1700  of  FIG. 17  or a method in accordance with  FIG. 4 . 
         [0153]    Routines  1910  include a first message processing module  1914 , a second message processing module  1916 , a third message generation module  1918 , a storage control module  1920 , a fourth message generation module  1922 , a forwarding information module  1924 , a first change request module  1926 , a second change request module  1928 , and a change indication message processing module  1930 . 
         [0154]    Data/information  1912  includes received first message  1932  which is processed by module  1914  and received second message  1936  which is processed by module  1916 . In some embodiments, the received first message  1932  includes a first identifier  1934 , and the first identifier had been transmitted in a message by a mobile having the mobile node address. In some embodiments, the received second message  1936  includes a node status flag  1938 , used to indicate one of a primary and secondary status, e.g., for one or more HACNs such as for the fourth node. Data/information  1912 , in some embodiments, includes primary/secondary status information for the 2 nd  node  1944 , e.g., information indicating whether the 2 nd  node, e.g., first HACN is currently considered the primary or secondary HACN, and primary/secondary 4 th  node status information  1946 , e.g., information indicating whether the fourth node, e.g., 2 nd  HACN is currently considered the primary or secondary HACN, e.g., of a pair of HACN as part of redundancy and/or fault management. 
         [0155]    In some embodiments, data/information  1912  includes an identifier of the second node  1940 , e.g., an identifier of the first HACN, or an identifier of the fourth node  1942 , e.g., an identifier of the second HACN. For example the stored identifier indicates which node is the current provider of forwarding information for packets including the MN address. 
         [0156]    In various embodiments, data/information  1912  includes one or more of: a generated third message  1948 , a generated fourth message  1950 , a generated first change request message  1958 , a generated second change request message  1960 , current provider information  1952 , most recent message information  1954 , local preference state information  1956 , and a received change indicator message  1962 . 
         [0157]    First message processing module  1914  is for receiving and processing a first message from the second node, e.g., first HACN, that includes first forwarding information, said first forwarding information to be used for forwarding packets including a mobile node address via the first node  1900 , e.g., first HATN, and an access node. Second message processing module  1916  is for receiving and processing a second message from the fourth node, e.g., second HACN, the second message including second forwarding information, the second forwarding information to be used for forwarding packets including said mobile node address via the first node  1900 , e.g., first HATN, and the access node. 
         [0158]    In various embodiments, the access node includes a mobile IP foreign agent. In some embodiments, the first forwarding information is a first binding between the mobile node address and a forwarding address, and the second forwarding information is a second binding between the mobile node address and the same forwarding address. In some embodiments, the first forwarding information is a first binding between the mobile node address and a forwarding address, and the second forwarding information is a second binding between the mobile node address and a different forwarding address. 
         [0159]    Storage control module  1920  controls the storage of information including, at times, information including an identifier of the second node, said identifier indicating that the second node, e.g., first HACN, is the current provider of forwarding information for packets including the MN address. Identifier of the second node  1940  is such an exemplary identifier, and it may have been stored by storage control module  1920  prior to receiving the second message. Third message generation module  1918  is for generating a third message directed to the second node, e.g., first HACN, the third message providing forwarding status information regarding forwarding performed by the first node for packets including the MN address. 
         [0160]    Storage control module  1920  controls storage of information including, at times, an identifier indicating that the fourth node, e.g., second HACN, is the current provider of forwarding information for packets including the MN address, the identifier being obtained from the received second message. Identifier of the fourth node  1942  is such an exemplary identifier. Fourth message generation module  1922  generates a fourth message directed to the fourth node, e.g., second HACN, the fourth message providing forwarding status information regarding forwarding performed by the first node  1900 , e.g., first HATN, for packets including the MN address. 
         [0161]    In various embodiments, the second message includes a flag used to indicate one of a primary and a secondary node status. Forwarding information module  1924  indicates that the fourth node is the current provider of forwarding information when the flag indicates that the fourth node is the primary node. 
         [0162]    In various embodiments, the first node maintains information indicating which one of the second node, e.g., first HACN, and the fourth node, e.g., second HACN, is the current provider of forwarding information for packets including the MN address. In some such embodiments, the storage control module  1920  control the memory to store information indicating which one of the second and the fourth node is the current provider of forwarding information for packets including the MN address. For example, the storage control module  1920  control the memory to store information indicating that the fourth node is the current provider when one of: (i) the second message is the most recently received message, (ii) the first node  1900 , e.g., first HATN, has local preference state indicating a preference for the fourth node, e.g., second HACN, over the second node, e.g., first HACN, for providing forwarding information. 
         [0163]    First change request module  1926  is for generating a change request message directed to the second node, e.g., first HACN, prior to receiving a second message, the change request message requesting that the second node, e.g., first HACN, stop providing forwarding information to the first node  1900 , e.g., first HATN, for packets including the MN address. Second change request module  1928  is for generating a change request message directed to the fourth node, e.g. second HACN, prior to receiving the second message, the change request message requesting that the fourth node provide forwarding information for packets including said mobile node address. 
         [0164]    Change indication message processing module  1930 , in some embodiments, processes a change indication message received from the fourth node, e.g. second HACN, the change indication message including information to be used by the first node  1900 , e.g., first HATN, for forwarding packets including the mobile node address via the access and indicating a changeover to the fourth node, e.g., second HACN. For example, the changeover is from the second node, e.g., first HACN to the fourth node, e.g., second HACN. 
         [0165]    Changeover indication message processing module  1930 , in some embodiments, processes a change indicator message from the second node, e.g. first HACN, indicating a changeover to the fourth node, e.g., second HACN, said changeover resulting in at least one message that includes information to be used by the first node, e.g., first HATN, for forwarding packets including the mobile node address via the access node being transmitted from the fourth node, e.g. second HACN, to the first node, e.g., first HATN. 
         [0166]      FIG. 20  is a drawing of an exemplary access node  2000 , e.g., base station, in accordance with various embodiments. The exemplary access node  2000  is for use in a communications system including the access node  2000 , a first node, e.g., a first home agent tunneling node (HATN), a second node, e.g., a first home agent control node (HACN), and a fourth node, e.g., a second HACN. In various embodiments, the exemplary communications system further includes another node, e.g., a home agent database node (HADN). In some embodiments, the second and fourth nodes are nodes which process binding update signaling for a binding between a mobile node address and a forwarding address used by the first node to forward packets including the mobile node address. Access node  2000  is, in some embodiments, access node  170  or  170 ′ described with respect to other figures. 
         [0167]    Access node  2000  includes a wireless transmitter module  2002 , a wireless receiver module  2004 , a processor  2006 , an I/O interface  2008  and a memory  2010  coupled together via a bus  2011  over which the various elements may interchange data and information. Wireless transmitter module  2002 , e.g., e.g., an OFDM, CDMA, or GSM transmitter, is coupled to transmit antenna  2012  via which the access node transmits downlink signals to wireless terminals, e.g., mobile nodes. Wireless receiver module  2004 , e.g., an OFDM, CDMA, or GSM receiver, is coupled to receive antenna  2014  via which the access node  2000  receives uplink signals from wireless terminals, e.g., mobile nodes. In some embodiments, the same antenna is used for transmitter and receiver. 
         [0168]    I/O interface  2008  couples the access node  2000  to other network nodes, e.g., other access nodes, a first node such as a first HATN, a third node such as a second HATN, a second node such as a first HACN, a fourth node such as a second HACN and another node such as a HADN. I/O interface  2008  allows a wireless terminal using an attachment point of access node  2000  to communicate with a peer node which is using an attachment point of a different access node. 
         [0169]    Memory  2010  includes routines  2016  and data/information  2108 . The processor  2006 , e.g., a CPU, executes the routines  2016  and uses the data/information  2018  in memory  2010  to control the operation of the access terminal  2000  and implement methods, e.g., a method in accordance with the flowchart  1100  of  FIG. 11 . Routines  2016  include a binding update message processing module  2020 , a forwarding module  2022 , a selection module  2024 , a mapping information updating module  2026 , a storage module  2028 , a retransmission time module  2030 , a retransmission module  2031 , a transmission failure detection module  2032 , a second identifier adding module  2034 , and a performance indication message generation module  2036 . Data/information  2018  includes information indicating a mapping between a MN address and identifiers of the second node, e.g., first HACN, and the fourth node, e.g., second HACN,  2038 . In various embodiments stored information  2038  is or includes a binding table. In some embodiments, information  2038  includes priority indicator information  2040 . Data/information  2018  also includes a received binding update message  2042  and selection result information  2044 . In various embodiments, information  2018  includes one or more of message portion processing performance information  2046  and message portion forwarding performance information  2048 . 
         [0170]    Binding update message processing module  2020  processes received binding update messages, e.g., message  2042 , the received binding update message including an MN address and a forwarding address, the forwarding address being used by a first node, e.g., a first home agent tunneling node, to forward packets including the MN address. In various embodiments, the forwarding address is an address of access node  2000  and the access node  2000  includes a Mobile IP foreign agent. 
         [0171]    Forwarding module  2022  is for forwarding a portion of the received message, e.g., message  2042 , to the second node, e.g., to the first HACN. Selection module  2024  selects between the second and fourth nodes, e.g., between first and second HACN nodes, as the destination of a portion of a received binding update message. In some embodiments, the forwarding module  2022  forwards a portion of the received binding update message to the second node, e.g., first HACN, after the selection module  2024  selects between the second node and fourth node as the destination of said portion of said received binding update message and selects the second node. In some such embodiments, the forwarding module  2022  forwards a portion of the received binding update message to the fourth node, e.g., second HACN, after the selection module selects between the second node and fourth node as the destination of said portion of said received binding update message and selects the fourth node. Selection result information  2044  is an output of the choice of the selection module  2024 . 
         [0172]    In some embodiments, the selection module  2024  performs the selection operation based on information included in the binding update message. In some such embodiments, at least some of the information including the binding update message is non-address information. 
         [0173]    In various embodiments, the selection module  2024  selects the second node rather than the fourth node as the destination for the message based on a priority indicator included in stored mapping information, e.g., priority indicator information  2040  included in mapping information  2038 , said priority indicator being associated with at least one of the second and fourth nodes, the priority indicator indicating that the second node has priority over the fourth node. 
         [0174]    Mapping information updating module  2026 , in some embodiments, processes a mapping updating message including updated mapping information that includes priority information that indicates changes in priority indication information to be made to stored priority information corresponding to at least one of the second and fourth nodes, e.g., first and second HACNs. Mapping information updating module  2026  also updates stored information  2038  based on the content of the received mapping update message. IN some embodiments, the received mapping update message was transmitted by one of: the second node, e.g., first HACN, the fourth node, e.g., second HACN, and the another node, e.g., HADN or AAA node including a home agent database. 
         [0175]    Storage module  2028  stores at least one of message portion processing performance information and message portion forwarding performance information regarding at least one previous message portion forwarded by the access node  2000  to one of the second and fourth nodes, e.g., first and second HACNs. Message portion processing performance information  2046  and message portion forwarding performance information  2048  are outputs out storage module  2028 . In some such embodiments, the selection module  2024  selects, at times, the second node rather than the fourth node as the destination of the message portion as a function of the stored performance information, e.g., as a function of one or more of message portion processing performance information  2046  and message portion forwarding performance information  2048 . 
         [0176]    Retransmission time module  2030  executes a retransmit timer associated with a forwarded message portion. Retransmission module  2031 , in some embodiments, controls the access node  2000  to retransmit the message portion to the second node, e.g., first HACN, when the retransmit timer expires prior to the reception of a response to a forwarded message portion and when the forwarded message portion was originally forwarded to the second node. Retransmission module  2031 , in some embodiments, controls the access node  2000  to retransmit the message portion to the fourth node, e.g., second HACN, when the retransmit timer expires prior to the reception of a response to a forwarded message portion and when the forwarded message portion was originally forwarded to the fourth node. 
         [0177]    Transmission failure detection module  2032  performs a second node transmission failure detection operation. Retransmission module  2031 , in some embodiments, controls the access node  2000  to transmit a portion of said message portion to the fourth node, e.g., second HACN, when the second node transmission failure detection process indicates a transmission failure. 
         [0178]    In various embodiments, the transmission failure detection module  2032  performs a fourth node transmission failure detection operation. Retransmission module  2031 , in various embodiments, controls the access node  2000  to transmit a portion of a message portion originally attempted to be communicated to the fourth node, to the second node, when the fourth node transmission failure detection process indicates a transmission failure. 
         [0179]    The received binding update message, e.g., message  2042 , may, and sometimes does, include a first identifier. Second identifier adding module  2034 , in some embodiments, adds a second identifier to a transmitted message portion, the value of the second identifier being different for the transmitted message portion and the retransmitted message portion. For example, the value of the second identifier, in some embodiments, indicates whether the transmitted message portion is a first transmission or is a retransmission. 
         [0180]    In some embodiments, the second identifier is different depending upon the node to which the message portion is being communicated. For example, in some embodiments, the second identifier adding module  2034  adds a second identifier to a portion of a received binding update message portion, the value of the second identifier being different when the transmission is to be to the fourth node, e.g., second HACN, as compared to when the transmission is to be to the second node, e.g., first HACN. 
         [0181]    In some other embodiments, the second identification module  2034  adds a second identifier to a portion of a message portion of the received binding update message to be transmitted to the fourth node, the value of the second identifier being the same as the value of the second identifier in the transmission of the message portion to the second node. Thus in some embodiments, the value of the second identifier does not change as a function of which HACN the message portion is being communicated to. 
         [0182]    Performance indication message generation module  2036  generates a performance indication message directed to one of the second node, e.g., first HACN, fourth node, e.g., second HACN, and another node, e.g., HADN, the performance indication information including performance information corresponding to the stored performance information, e.g., information corresponding to information  2046  and/or  2048 . 
         [0183]    Mapping information updating module  2026 , in some embodiments, processes a mapping information message including updated mapping information, the updated mapping information including at least one of a second node identifier and a standby node identifier, said standby node identifier corresponding to a standby node to be used in place of the fourth node, e.g., second LACN, with respect to processing of binding update messages including the mobile node address. 
         [0184]    Various novel embodiments support methods other than IP in IP tunnels for packet redirection between the first or third nodes  110 ,  130  and the access node  170  or MN  160  said methods including for example, IPv6 routing headers, GRE tunnels, IPSEC tunnels, as well as VPN techniques such as MPLS and switched circuits. 
         [0185]    Whilst various exemplary embodiments have been described for MIP based HA Control and Tunnel Nodes and MIP like mobility RREQ/RREP signaling, the novel features, methods and/or apparatus are applicable to other signaling protocols from control nodes like the second and fourth nodes  120 , 140  which request that a first or third node  110 , 130  establish forwarding of packets that include a MN address  161  to the Mobile Node  160  via an Access Node  170 . Such control and forwarding nodes include the PDSN, GGSN, SGSN, RNC, BS, BSC, MSc in IMT2000, 3GPP and CDMA2000 type networks and there successors. Various features are implemented using modules. Such modules may be implemented using software, hardware or a combination of software and hardware. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RAM, floppy disk, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods. Accordingly, among other things, the various embodiments are directed to a machine-readable medium including machine executable instructions for causing a machine, e.g., processor and associated hardware, to perform one or more of the steps of the above-described method(s). Messages which are generated and/or transmitted in accordance with the various embodiments are stored on machine readable medium, e.g., in memory (RAM) in the device generating, transmitting and/or receiving the message or messages. Various embodiments are directed to, among other things, memory storing novel messages. 
         [0186]    In some embodiments, the processor or processors, e.g., CPUs, of one or more devices, e.g., communications devices such as access nodes, home agent control nodes or home agent tunneling nodes, are configured to perform the steps of the methods described as being performed by the communications device. Accordingly, some but not all embodiments are directed to a device, e.g., communications device, with a processor which includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. In some but not all embodiments a device, e.g., communications device, includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. The modules may be implemented using software and/or hardware. 
         [0187]    Numerous additional variations on the methods and apparatus of the various exemplary embodiments described above will be apparent to those skilled in the art in view of the above description. Such variations are to be considered within scope. The methods and apparatus of the various embodiments may be used with CDMA, orthogonal frequency division multiplexing (OFDM), or various other types of communications techniques which may be used to provide wireless communications links between access nodes such as base stations and mobile nodes. Accordingly, in some embodiments base stations establish communications links with mobile nodes using OFDM or CDMA. In various embodiments the mobile nodes are implemented as notebook computers, personal data assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the novel methods.

Technology Category: h