Under Simple Multicast Extension for Mobile IP, when a mobile node arrives at a foreign wireless domain, it listens for an agent advertisement sent by a foreign agent. The foreign agent attaches a network access identifier (NAI) extension to the agent advertisement. The mobile node uses the NAI extension to decide which action to take. If the mobile node determines that it is receiving an agent advertisement message from the same foreign agent it previously was in communication with, no action is required. If the mobile node discovers that it has entered a new foreign domain, it sends a registration request to the foreign agent. If the mobile node identifies that it is still in the same domain but has moved from a previous foreign agent to a new one, it sends a multicast subscription request to the new foreign agent. If a home agent supports the Simple Multicast Extension for Mobile IP, it allocates a source specific multicast address and inserts the address in a source specific multicast address extension after the registration reply. In addition, tunneling is used to route datagrams from correspondent nodes to the mobile node while the mobile node is in a foreign domain. The destination address of the tunnel is set to the source specific multicast previously allocated. Finally, update messages are used to inform correspondent nodes of a mobile nodes' new location.