Patent ID: 8553534

Claim:
A method of delivering multicast data traffic over a communication network comprising a first network node adapted in operation to deliver multicast data traffic to at least two second network nodes and wherein the first and second network nodes are connected to each other by a transmission network in a ring architecture and implement a point-to-multipoint layer 2 protocol, the method comprising: at the first network node: collecting alarm signals indicative of a failure condition of the transmission network along the whole ring and of the at least two second network nodes, and based on a current state of the alarm signals: delivering the multicast data traffic in a first delivery direction along the ring when no fault is detected; delivering the multicast data traffic in a second delivery direction along the ring opposite to the first delivery direction if the collected alarm signals indicate a failure condition of a first type, wherein the failure condition of the first type comprises at least one of: a failure of a network node directly connected to the first network node and a failure of a portion of the transmission network between the first network node and the network node directly connected to the first network node; and delivering the multicast data traffic in both the first and second delivery directions along the ring if the collected alarm signals indicate a failure condition of a second type different from the first type, wherein the failure condition of the second type comprises at least one of: a failure of a network node not directly connected to the first network node and a failure of a portion of the transmission network not directly connected to the first network node; at each of the at least two second network nodes: collecting local alarm signals indicative of a failure condition of the transmission network locally to the second network node and of the second network node, and based on a current state of the local alarm signals: either receiving the multicast data traffic delivered by the first network node from the first delivery direction along the ring, forwarding the multicast data traffic in the first delivery direction along the ring, and transmitting local data traffic to the first network node along the second delivery direction, or receiving the data traffic delivered by the first network node from the second delivery direction along the ring, forwarding the multicast data traffic in the second delivery direction along the ring, and transmitting the local data traffic to the first network node along the first delivery direction along the ring.