An apparatus in MVPN, Multicast Virtual Private Network, extranet using any-source multicast, ASM, the apparatus comprising: a first network device adapted for communication with a plurality of other network devices (PE1, 110-4); the first network device comprising: a service routing element configured with a first anycast rendezvous point address, wherein the service routing element is an anycast rendezvous point peer with at least a second network device in a service routing domain; and a client routing element (112, 114) configured with a second anycast rendezvous point address, wherein the client routing element (112, 114) is an anycast rendezvous point peer with at least a third network device in a client routing domain; wherein the first network device is configured to receive in its service routing element from a service routing element of the second network device a register message identifying a multicast source, and wherein the first network device is configured to provide at least a portion of the register message from its service routing element to its client routing element (112, 114), wherein the third network device learns the identity of the multicast source from the client routing element (112, 114). a first network device adapted for communication with a plurality of other network devices (PE1, 110-4); the first network device comprising: a service routing element configured with a first anycast rendezvous point address, wherein the service routing element is an anycast rendezvous point peer with at least a second network device in a service routing domain; and a client routing element (112, 114) configured with a second anycast rendezvous point address, wherein the client routing element (112, 114) is an anycast rendezvous point peer with at least a third network device in a client routing domain; wherein the first network device is configured to receive in its service routing element from a service routing element of the second network device a register message identifying a multicast source, and wherein the first network device is configured to provide at least a portion of the register message from its service routing element to its client routing element (112, 114), wherein the third network device learns the identity of the multicast source from the client routing element (112, 114). a service routing element configured with a first anycast rendezvous point address, wherein the service routing element is an anycast rendezvous point peer with at least a second network device in a service routing domain; and a client routing element (112, 114) configured with a second anycast rendezvous point address, wherein the client routing element (112, 114) is an anycast rendezvous point peer with at least a third network device in a client routing domain; wherein the first network device is configured to receive in its service routing element from a service routing element of the second network device a register message identifying a multicast source, and wherein the first network device is configured to provide at least a portion of the register message from its service routing element to its client routing element (112, 114), wherein the third network device learns the identity of the multicast source from the client routing element (112, 114).