Mobile node handoff methods and apparatus

#The present invention is directed to establishing and managing a data communication session and, more particularly, to establishing a data communication session through an access node (AN) in a multi-node network, e.g., a cellular network in which mobile end nodes communicate with each other and other end systems through ANs. ANs are commercially sometimes also known as RadioRouters (RR).

#Internet Protocol (IP) technology is designed to enable packet-switched interconnection of a heterogeneous set of devices (e.g., computers) and communication networks. A potentially diverse set of network and link layer technologies are interconnected through nodes, e.g., gateways (or routers), that provide a packet forwarding service. Information is transferred between “end nodes” (or hosts) as blocks of data called datagrams, where source and destination hosts are identified by fixed length addresses. Routing in IP internetworks is connectionless in nature, in that datagrams are forwarded by routers on a hop-by-hop basis using the destination address in the datagram.

#Mobile IP (MIP) (Ref: IETF RFC 2002, incorporated herein by reference) enables an IP host, also called a “Mobile Node” (MN) in the context of Mobile IP, to dynamically change its point of attachment to the network, yet remain contactable via a previously given “home address”. To achieve this, a temporary local address or “care of address” is associated with the MN when it visits a foreign network, the visited network. In some cases the care of address is that of a “foreign agent” that assists in this process, while in other cases the care of address may be directly assigned to the MN. The care of address is registered back on the home network in a node referred to as the “home agent”. The home agent intercepts packets destined to the home address of the MN and redirects the packets, by means of encapsulation and tunneling, towards the care of address associated with MN in the visited network. Upon delivery to the care of address, the encapsulation is removed and the original packet destined to the home address is delivered to the MN.

#FIG. 1 illustrates an exemplary communications system including two network domains, an End Node (EN), an Access node (AN or oAN), a Regional Roaming node (RN or oRN), a Home Agent node (HA), exemplary packet flow, and exemplary signaling in accordance with the present invention.

#FIG. 2 illustrates a prior art binding table that is used in a standard MIP Home Agent of Foreign Agent.

#FIG. 3 illustrates a exemplary binding table that is located in an RN in accordance with the present invention.

#The present application is directed to mobility management in a communications system, in which handoff operations occur, e.g., when a wireless terminal such as a mobile node changes its point of network attachment from one access node to another access node. In various embodiments of the invention, a mobile node involved in a handoff implements multiple IP clients resulting in multiple forwarding addresses being used. Each IP client may correspond to a different type of network access, e.g., with one IP client being used to obtain local network access in the region in which a mobile is located at any point in time and another IP client being used to obtain remote network access, e.g., access from the mobile node's home domain or region which the mobile node is visiting a foreign network domain or region. A single integrated IP client can alternatively be used to manage both local and remote addresses. In the present application the term old and new are generally used in the context of a handoff operation. In the case of a handoff the term “old” is normally used to refer to an existing connection, or relationship while the term “new” is to refer to a connection or relationship which is being established. In the context of node descriptions, new is generally used to refer to a node which will replace a like named node in terms of functionality as a result of a hand off. For example new Access Node refers to the node to which a mobile is being handed off to while old access node refers to the Access Node from which the mobile node is being handed off from.

#Each node illustrated in the present figures includes memory for storing messages which are received or generated by the node. In some implementations the memory is part of an interface buffer located in an I/O interface corresponding to the message point of ingress to a node or egress from a node. In other embodiments, the memory is part of a general memory in the node used to store, e.g., one or more binding tables. Accordingly, among other things, the present invention is directed to novel messages stored in a memory device, e.g., node I/O buffer, wherein the messages are any one of the messages illustrated in the figures of the present application and wherein the memory device used to store the illustrated messages is memory included in the illustrated nodes.

#In describing the invention, various acronyms are used. While many of the acronyms are well known MIP terms, for purposes of clarity a list of acronym's and there meaning follows. 1 ACRONYM MEANING MIP Mobile IP (protocol, message or node) LA Local access (message or service configured by message) RA Remote access (message or service configured by message) LARA Combined local and remote access (message or services configured by message) EN End Node MN Mobile Node CN Correspondent Node o old (used as prefix to other term) n new(used as prefix to other term) AN Access Node oAN Old Access Node nAN New Access Node RN Roaming Node also sometimes called Regional Node oRN Old Roaming/Regional Node oRoA Regional Address from the prefix assigned to the oRN nRN New Roaming/Regional Node nRoA Regional Address from the prefix assigned to the nRN RMA Regional Mobility agent module in RN or HA node. HA Home Agent (node and/or module) bA Home Address from the prefix assigned to the HA FA Foreign Agent module (normally in AN or HA node) CoA Care of Address from the prefix assigned to an AN. CCoA Colocated CoA SHCoA CoA at a Foreign Agent (commonly known as FA CoA) MSCoA Mobile Specific CoA at a Foreign Agent (also sometimes known as Proxy CCoA (PCCoA)) PRAA Previous Regional Agent Authenticator PRANE Previous Regional Agent Notification Extension PFAA Previous Foreign Agent Authenticator PFANE Previous Foreign Agent Notification Extension BU Binding Update Buack Binding Update acknowledgement RREQ Registration Request RREP Registration Reply GFA Gateway Foreign Agent HFAIP IP address of a hierarchical agent such as an RMA. HFAext CoA at a hierarchical foreign agent such as an RMA. Stylext Extension describing the redirection Style AAA Authentication, Authorization & Accounting NAT Network Address Translation SA Source address DA Destination address