Patent ID: 7590120

Claim:
A method comprising: configuring first and second ring ports of a first layer 2 access switch to be part of a multicast VLAN, with the multicast VLAN including ring ports on layer 2 access switches and on a layer 3 device included in a network, with the layer 2 access switches and layer 3 network device coupled in a ring topology, where the multicast VLAN is the only VLAN over which multicast data, identified by a first multicast address flows; configuring a first non-ring port of the first layer 2 access switch as a first Ethernet VLAN trunk port for transmitting traffic between multiple VLANs, where different VLANs are identified by different VLAN id tags and where the first non-ring port of the first layer 2 access switch is coupled by an Ethernet trunk line to first and second hosts included in respective first and second VLANs; receiving, at the first VLAN Ethernet trunk port of the first layer 2 access switch, a first multicast join message from the first host indicating the first multicast address and including a first VLAN id tag of the first VLAN including the first host; intercepting the multicast join message at the first layer 2 access switch so that it is not forwarded; creating a modified first multicast join message, in response to the first multicast join message, indicating that the ring port of the first layer 2 access switch, included in the multicast VLAN, wishes to join a first multicast group that receives multicast packets indicated by the first multicast address; forwarding the first modified multicast join message to the layer 3 device; and forwarding multicast packets, multicast over the multicast VLAN, to the first Ethernet VLAN trunk port and tagging forwarded multicast packets with the first VLAN id tag.