A method of notifying a first communication network of a fault related to a second communication network, said first communication network connected to said second communication network, said first communication network having a first OAM protocol adapted to monitor integrity of said first communication network, said second communication network having a second OAM protocol adapted to monitor integrity of said second communication network, said method comprising:
- detecting said fault related to said second communication network;
- generating a first OAM cell of said first OAM protocol indicating detection of said fault;
- transmitting said first OAM cell to said first communication network to indicate said fault to said first communication network.