Patent ID: 6988146

Claim:
A method for multicasting internet protocol (IP) messages to mobile nodes in a wireless network having a home domain comprising a home agent and at least one foreign domain having a foreign agent, wherein each of the home and foreign domains further comprise a main access router attached to a plurality of base station routers, and wherein each base station router is connected to one or more base stations for communicating with mobile nodes in a coverage area of the base station router, comprising the steps of: transmitting an agent advertisement message from a foreign agent in a foreign domain to be broadcast in the foreign domain, wherein the agent advertisement message includes a network access identifier extension that indicates a capability of the foreign agent to support source specific multicast services for multicasting IP messages; receiving by a base station router in the foreign domain a mobile IP registration request from a mobile node entering the coverage area of the base station router, wherein the mobile IP registration request includes a request by the mobile node to access the foreign domain and a multicast flag to indicate a request for source specific multicast services; in response to determining no registration of the mobile node in a binding cache of the base station router, performing the following steps: appending an IP address of the base station router in a BSR extension to the mobile IP registration request; transmitting by the base station router the mobile IP registration request with the BSR extension to the main access router in the foreign domain; forwarding the mobile IP registration request from the main access router in the foreign domain to a home agent in a home domain of the mobile node; if the home agent supports simple multicast extensions for multicasting IP messages, allocating a source specific multicast address to the mobile node and appending the source specific multicast address in a source specific multicast address extension to a mobile IP registration reply; receiving by the base station router the mobile IP registration reply from the main access router, wherein the mobile IP registration reply includes the source specific multicast address-extension; creating an entry in a binding cache of the base station router having information on the mobile node and assigned source specific multicast address extension; and forwarding the registration reply and source specific multicast address to the mobile node, wherein the mobile node then subscribes to the source specific multicast channel.