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Permitting a mobile host to roam in a foreign network, with multiple access node handoffs, while permitting foreign network multicasting by (i) having the mobile node (MN) use a persistent address, for purposes of multicasting, and (ii) relaxing or modifying reverse path forwarding checks, and (iii)

Permitting a mobile host to roam in a foreign network, with multiple access node handoffs, while permitting foreign network multicasting by (i) having the mobile node (MN) use a persistent address, for purposes of multicasting, and (ii) relaxing or modifying reverse path forwarding checks, and (iii) modifying the forwarding of multicast packets sent from a non-local source address. The persistent address, used in mobile networks as the source address in the IGMP Membership reports and the multicast packets, may be the permanent and hence stable host home address (HoA). This enables the HoA to be supported as a source address by foreign agents (FAs) and multicast routing protocols in foreign networks.

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What is claimed is: 1. A method for use with a communications system including a first network system serving as a home network for a mobile node and including a first mobility agent which is coupled to a home network multicast system, and a second, network system, said second network system includ

What is claimed is: 1. A method for use with a communications system including a first network system serving as a home network for a mobile node and including a first mobility agent which is coupled to a home network multicast system, and a second, network system, said second network system including an access node and a foreign network multicast system, the access node including: a second mobility agent, and a multicast facility; the method comprising: a) submitting, from the mobile node, a signaling message to the multicast facility of the access node for joining a multicast data communications group in the foreign network multicast system; and b) sending, from the mobile node, unencapsulated multicast data to the multicast data communications group, via the access node, using a source address that is not local to the second, visited, network system. 2. The method of claim 1, wherein the source address is a persistent address. 3. The method of claim 1 wherein the source address is a host home address. 4. The method of claim 1 further comprising: c) moving the mobile node so that it is no longer served by the access node, but is served by another access node of the second, visited network system. 5. The method of claim 1 wherein the signaling message is submitted, unencapsulated, to the access node. 6. A method for use with a communications system including a mobile node, a first network system serving as a home for the mobile node and including a first mobility agent and a home network multicast system, and a second, visited, network system including an access node and a foreign network multicast system, the method comprising: a) accepting, by the access node in the second, visited, network system, multicast group information, including a non-local address, from the mobile node; and b) storing, by the access node, the multicast group information to be used for the reception of multicast data from the foreign network multicast system. 7. The method of claim 6 wherein the access node has an address, the method further comprising: c) distributing, from the access node, the address of the access node as a source-specific reverse path forwarding address. 8. The method of claim 6 further comprising: c) accepting, by the access node, a multicast packet from the mobile node; d) determining, by the access node, whether or not to forward the multicast packet based on mobility information, related to the mobile node, and used by the access node. 9. A method for use with a communications system including a mobile node, a first network system serving as a home for the mobile node and including a first mobility agent, and a second, visited, network system including an access node, the method comprising: a) accepting, by the access node, multicast group information, including a non-local address, from the mobile node; b) storing, by the access node, the multicast group information c) accepting, by the access node, a multicast packet from the mobile node; d) determining, by the access node, whether or not to forward the multicast packet based on mobility information, related to the mobile node, and used by the access node, wherein the step of determining whether or not to forward the multicast packet: i) determines whether a source address of the multicast packet is on a visitor list; and ii) if it is determined that the source address of the multicast packet is on the visitor list, then considering the multicast packet to have passed a reverse path forwarding check, despite the fact that the source address is a non-local address. 10. The method of claim 8 further comprising: e) if the access node is a multicast router running a shared tree protocol specifying a shared tree having a root, then tunneling the accepted multicast packet to the root of the tree. 11. The method of claim 10 wherein the shared tree protocol is Protocol Independent Multicast-Sparse Mode and the root of the shared tree is a rendezvous part node. 12. A method for use with a communications system including a mobile node, a first network system serving as a home for the mobile node and including a first mobility agent, and a second, visited, network system including an access node, the method comprising: a) accepting, by the access node, multicast group information, including a non-local address, from the mobile node; b) storing, by the access node, the multicast group information c) accepting, by the access node, a multicast packet from the mobile node; d) determining, by the access node, whether or not to forward the multicast packet based on mobility information, related to the mobile node, and used by the access node, and e) if the access node is not a multicast router, then tunneling an instance of the packet to a designated router of the multicast group with sufficient mobility information to enable the designated router to support non-local source addresses multicasting. 13. A method for use with a communications system including a mobile node, a first network system serving as a home for the mobile node and including a first mobility agent, and a second, visited, network system including an access node, the method comprising: a) accepting, by the access node, multicast group information, including a non-local address, from the mobile node; and b) storing, by the access node, the multicast group information; and wherein the access node includes a mobility facility and a multicast facility, the method further comprising: d) using mobility state information to validate that the non-local source address is assigned to the mobile node; e) installing, with the multicast facility, a multicast routing entry into the local multicast forwarding table pointing multicast data packets sent from said mobile node to a multicast group, towards an outgoing interface and associated interface processing, said interface and interface processing then being determined by the set of mobility information and by multicast facility information. 14. An access node for use in a multicast communications system, the access node comprising: a) a multicast facility for supporting multicast operations including multicast establishment and forwarding operations; and b) a mobility facility for supporting the roaming to, and multicast connectivity at said access node, of a mobile end node, wherein the mobile end node uses a non-local address for the reception of local multicast data from other nodes in a foreign network multicast system, said non-local address corresponding to a home network. 15. The access node of claim 14 wherein the non-local address used by the mobile node is a Mobile Internet Protocol home address. 16. The access node of claim 14 further comprising: c) a wireless interface for effecting a wireless link with the mobile node. 17. The access node of claim 14 further comprising: c) an interface for coupling the access node to another node, the another node including a multicast routing and forwarding process. 18. The access node of claim 14, wherein said multicast facility includes an Internet Group Management Protocol process and a multicast routing and forwarding process. 19. The access node of claim 14, wherein said multicast facility includes means for generating Internet Group Management Protocol signals as part of a multicast group membership query operation used to determine multicast group membership interests of the mobile node. 20. An access node for use in a multicast communications system, the access node comprising: a) a multicast facility for supporting multicast operations including multicast establishment and forwarding operation; b) a mobility facility for supporting the roaming to, and multicast connectivity at said access node, of a mobile end node, wherein the mobile end node uses a non-local address for local multicast services; c) a set of available mobility state information; d) a set of available multicast state information; and e) means for correctly forwarding multicast data from the mobile node into a multicast system, despite the fact that the source address of the multicast packets are not local to the access node, using the set of available mobility state information. 21. The access node of claim 14, wherein said mobility facility supports Mobile Internet Protocol signaling. 22. The access node of claim 14 wherein the mobility facility includes an Mobile Internet Protocol version 4 foreign agent. 23. The access node of claim 14, wherein the mobility facility includes an Mobile Internet Protocol version 6 attendant. 24. The access node of claim 14, wherein the multicast facility includes means for undertaking a modified reverse path forwarding check on the source address of multicast data packets. 25. A mobile node belonging to a first network system and having a home agent in the first network system, for use in a multicast communications system of a second, visited, network system including a foreign network multicast system and an access node, said access node including: a foreign mobility agent, and a multicast facility, the mobile node comprising: a) means for generating a signaling message to the multicast facility of the access node for joining a multicast data communications group at the foreign network muticast system; and b) means for generating multicast data to the multicast data communications group, using a multicast source address that is not local to the second, visited, network system; and c) means for transmitting the signaling message and multicast data to the access node. 26. The mobile node of claim 25, wherein the source address is a persistent address. 27. The mobile node of claim 25 wherein the source address is a host home address. 28. The mobile node of claim 25 wherein the means for transmitting facilitates wireless transmission such that the mobile node can be moved so that it is no longer served by the access node, but is served by another access node of the second, visited network system. 29. The mobile node of claim 25 wherein the means for transmitting transmits the signaling message, unencapsulated, to the access node. 30. The mobile node of claim 25, further comprising: d) a set of available mobility state information; and e) a set of available multicast state information. 31. The mobile node of claim 25 wherein means for generating a signaling message supports Mobile Internet Protocol signaling. 32. The mobile node of claim 25 wherein the means for generating a signaling message supports Mobile Internet Protocol Version 4 mobile node. 33. The mobile node of claim 25 wherein the means for generating a signaling message supports Mobile Internet Protocol Version 6 mobile node. 34. A multicast communications system comprising: a) an access node in a first foreign network, said access node being coupled to a first foreign network multicast system also included in said first foreign network, said access node also being coupled to a home network multicast system in a home network and b) a mobile node belonging to said home network, said mobile node being coupled to said access node, said mobile node using a non-local source address when multicasting, via the access node; and wherein said access node receives multicast data from the foreign network multicast system and forwards said multicast data to the mobile node. 35. The method of claim 1 further comprising: accepting, by the access node, multicast group information, including a non-local address, from the mobile node; and storing, by the access node, the multicast group information. 36. The method of claim 35 wherein the access node has an address, the method further comprising: distributing, from the access node, the address of the access node as a source-specific reverse path forwarding address. 37. The method of claim 35 further comprising: accepting, by the access node, a multicast packet from the mobile node; determining, by the access node, whether or not to forward the multicast packet based on mobility information, related to the mobile node, and used by the access node. 38. A method for use with a communications system including a first network system serving as a home for a mobile node and including a first mobility agent, and a second, visited, network system including an access node including a second mobility agent, and a multicast facility the method comprising: submitting, with the mobile node, a signaling message to the multicast facility of the access node for joining a multicast data communications group; and sending, from the mobile node, unencapsulated multicast data to the multicast data communications group, via the access node, using a source address that is not local to the second, visited, network system; accepting, by the access node, multicast group information, including a non-local address, from the mobile node; storing, by the access node, the multicast group information; accepting, by the access node, a multicast packet from the mobile node; determining, by the access node, whether or not to forward the multicast packet based on mobility information, related to the mobile node, and used by the access node; and wherein the step of determining whether or not to forward the multicast packet: i) determines whether a source address of the multicast packet is on a visitor list; and ii) if it is determined that the source address of the multicast packet is on the visitor list, then considering the multicast packet to have passed a reverse path forwarding check, despite the fact that the source address is a non-local address. 39. The method of claim 37 further comprising: if the access node is a multicast router running a shared tree protocol such as Protocol Independent Multicast-Sparse Mode then tunneling the accepted multicast packet to the root of the tree. 40. The method of claim 39 wherein the shared tree protocol is Protocol Independent Multicast-Sparse Mode and the root of the shared tree is a rendezvous part node. 41. A method for use with a communications system including a first network system serving as a home for a mobile node and including a first mobility agent, and a second, visited, network system including an access node including a second mobility agent, and a multicast facility the method comprising: submitting, with the mobile node, a signaling message to the multicast facility of the access node for joining a multicast data communications group; and sending, from the mobile node, unencapsulated multicast data to the multicast data communications group, via the access node, using a source address that is not local to the second, visited, network system; accepting, by the access node, multicast group information, including a non-local address, from the mobile node; storing, by the access node, the multicast group information; accepting, by the access node, a multicast packet from the mobile node; determining, by the access node, whether or not to forward the multicast packet based on mobility information, related to the mobile node, and used by the access node; and if the access node is not a multicast router, then tunneling an instance of the multicast packet to a designated router of the multicast group with sufficient mobility information to enable the designated router to support non-local source addresses multicasting. 42. A method for use with a communications system including a first network system serving as a home for a mobile node and including a first mobility agent, and a second, visited, network system including an access node including a second mobility agent, and a multicast facility the method comprising: submitting, with the mobile node, a signaling message to the multicast facility of the access node for joining a multicast data communications group; and sending, from the mobile node, unencapsulated multicast data to the multicast data communications group, via the access node, using a source address that is not local to the second, visited, network system; accepting, by the access node, multicast group information, including a non-local address, from the mobile node; storing, by the access node, the multicast group information; wherein the access node includes a mobility facility and a multicast facility, the method further comprising: using mobility state information to validate that the non-local source address is assigned to the mobile node; installing, with the multicast facility, a multicast routing entry into the local multicast forwarding table pointing multicast data packets sent from said mobile node to a multicast group, towards an outgoing interface and associated interface processing, said interface and interface processing then being determined by the set of mobility information and by multicast facility information. 43. A method for use with a communications system including a first network system serving as a home for a mobile node and including a first mobility agent, and a second, visited, network system including an access node including a second mobility agent, and a multicast facility the method comprising: a) submitting, with the mobile node, a signaling message to the multicast facility of the access node for joining a multicast data communications group; and b) sending, from the mobile node, unencapsulated multicast data to the multicast data communications group, via the access node, using a source address that is not local to the second, visited, network system; and (c) accepting, by the access node, an indication of whether or not the first mobility agent supports hybrid multicasting. 44. The method of claim 43 wherein the indication is a Mobile Internet Protocol registration reply. 45. The method of claim 1, further comprising: c) receiving at the mobile node multicast data with a destination address corresponding to said multicast data communications group, said multicast data having been forward to the access node by the foreign network multicast system prior to transmission to said mobile node.