Routing Method for Mobile Wireless Nodes Having Overlapping Internet Protocol Home Addresses

Abstract

In mobile IP wireless data networking, methods are described for correctly routing packets through a foreign agent to or from wireless nodes where the wireless nodes have the same home network IP address. Instead of using normal IP routing, the foreign agent uniquely identifies the wireless node's home network IP address and home agent IP address with a PPP link address associated with a PPP link between the foreign agent and the wireless node. This association between PPP link addresses, home agent IP addresses, and home network IP addresses, is preferably implemented in software as a table stored in the foreign agent. The routing of packets through the foreign agent to the mobile nodes is performed by reference to the table. The table allows the foreign agent to correctly and efficiently route packets in the situation where multiple wireless nodes are registered with the foreign agent, but more than one of the wireless nodes have the same home network IP address.

1 . A communication system for communicating with a plurality of mobile nodes in a communication system, the communication system having a plurality of home agents, the plurality of home agents managing multiple Internet Protocol (IP) address pools having overlapping IP addresses, each pool being associated with a unique home agent IP address, wherein a home IP address for a given mobile node is associated with one of the multiple pools, the system comprising:
 a foreign agent configured to use a combination of the home IP address and an IP address of a home agent from a packet to identify a unique point-to-point protocol (PPP) link for the given mobile node; and   wherein the foreign agent receives a plurality of packets from the plurality of home agents, at least one of the packets contains an IP address of a home agent, is destined for the given mobile node, and has the same assigned home IP address as at least one other mobile node; and the foreign agent routes the packet to the given mobile node using the unique PPP link.   
   
   
       2 . The communication system of  claim 1 , wherein the foreign agent:
 receives a packet on a PPP link from a mobile node and the packet contains a home IP address; and   determines a unique home agent IP address from a combination of the PPP link and the home IP address, and routes the packet to the unique home agent IP address.   
   
   
       3 . A foreign agent for use in a communication system for communicating with a plurality of mobile nodes, wherein the communication system comprises a plurality of home agents, the plurality of home agents managing Internet Protocol (IP) addresses included in multiple address pools, the multiple address pools having one or more overlapping IP addresses and each pool being associated with a unique home agent IP address, the foreign agent comprising:
 a processing device;   a storage device having a plurality of machine executable instructions that, when executed by the processing device, provide for the processing device:
 using a combination of (i) an assigned home IP address of a given mobile node of the plurality of mobile nodes and (ii) an IP address of a home agent of the plurality of home agents with which the given mobile node is associated, to identify a unique point-to-point protocol (PPP) link for the given mobile node; 
 receiving a plurality of packets from the plurality of home agents, each packet containing an IP address of the respective home agent, wherein at least one packet is destined for the given mobile node, and wherein the given mobile node has the same assigned home IP address as at least one other mobile node of the plurality of mobile nodes; and 
 routing a packet destined for the given mobile node using the unique PPP link. 
   
   
   
       4 . The foreign agent of  claim 3 , wherein the plurality of machine instructions further provide for:
 receiving a packet on the unique PPP link associated with the given mobile node, the packet containing the assigned home IP address of the given mobile node;   determining a home agent IP address with the unique PPP link; and   routing the packet to a home agent associated with the home agent IP address.   
   
   
       5 . The foreign agent of  claim 4 , wherein the foreign agent is implemented in a remote access server. 
   
   
       6 . A foreign agent for routing a packet associated with a given mobile node, the foreign agent comprising:
 machine executable instructions that, when executed, provide for processing the packet associated with the given mobile node, the processing including:
 associating a home Internet Protocol (IP) address and a home agent IP address contained in the packet to determine a unique point-to-point protocol (PPP) link corresponding with the given mobile node, wherein the given mobile node has the same assigned home IP address as at least one other mobile node served by the foreign agent; and 
 routing the packet to the given mobile node via the unique PPP link. 
   
   
   
       7 . The foreign agent of  claim 6 , wherein the instructions further provide for:
 maintaining a table mapping PPP links to unique pairs of home IP addresses and home agent IP addresses, wherein associating home IP addresses and home agent IP addresses is accomplished by reference to the table, such that multiple mobile nodes having the same home IP addresses but different home agent IP addresses may be distinguished from each other.   
   
   
       8 . The foreign agent of  claim 6 , wherein the foreign agent comprises a remote access server for establishing respective PPP links with one or more mobile nodes.