Patent ID: 8331367

Claim:
A method of installing forwarding state in a first link state protocol controlled network node having a topology database representing a topology of the network, the method comprising: detecting whether an “unsafe” condition exists and, when an “unsafe” condition is detected, removing forwarding state for multicast trees originating at a second node in the network; subsequently advertising a “safe” indication signal to each neighbour node of the first node, the “safe” indication signal comprising a digest of the topology database; and installing forwarding state associated with a multicast path in a filtering database (FDB) of the first node when a predetermined “go” condition is satisfied, the “go” condition comprising receiving at least one respective “safe” indication signal from at least one neighbour node, each received “safe” indication signal containing a respective topology database digest matching the topology database digest of the “safe” indication signal advertised by the first node.