Method and apparatus for providing a more efficient use of the total bandwidth capacity in a synchronous optical network

A method for performing protection switching in a local node of a synchronous optical network ring, said local node including:

• a first group of working transmission lines for exchanging data with a first remote node in the network;
• a first protection line associated with said first group of working transmission lines, said first protection line being capable of exchanging data with the first remote node in the network;
• a second group of working transmission lines for exchanging data with a second remote node in the network, different from the first remote node;
• a second protection line associated with said second group of working transmission lines, said second protection line being capable of exchanging data with the second remote node in the network;
• said method comprising:
• a) monitoring each line of said first and second groups of working transmission lines;
• b) detecting a data transmission impairment of a first type over a particular line of said first group of working transmission lines, and re-routing the exchange of optical signals between said local node and the first remote node from the particular working transmission line to said first protection line;
• c) detecting a data transmission impairment of the second type between said local node and the first remote node, and re-routing optical signals from a particular working transmission line of said first group of working transmission lines to said second protection line.

A local node for use in a synchronous optical network ring, said local node comprising:

• a first group of working transmission lines for exchanging data with a first remote node in the network;
• a first protection line associated with said first group of working transmission lines, said first protection line being capable of exchanging data with the first remote node in the network;
• a second group of working transmission lines for exchanging data with a second remote node in the network, different from the first node;
• a second protection line associated with said second group of working transmission lines, said second protection line being capable of exchanging data with the second remote node in the network;
• control means operative to monitor said first and second groups of working transmission lines and,
• a) upon detection of a data transmission impairment of a first type over any one of the lines in the first group of working transmission lines, invoke a first protection switch event causing re-routing of optical signals from the working transmission line on which the data transmission impairment of the first type has been detected to said first protection line;
• b) upon detection of a data transmission impairment of a second type between said local node and the first remote node, invoke a second protection switch event causing re-routing of optical signals from a particular working transmission line of said first group of working transmission lines to said second protection line.

A synchronous optical network including a plurality of nodes, each node comprising:

• a first group of working transmission lines for exchanging data with a first remote node in the network;
• a first protection line associated with said first group of working transmission lines, said first protection line being capable of exchanging data with the first remote node in the network;
• a second group of working transmission lines for exchanging data with a second remote node in the network, the second remote node being different from the first remote node;
• a second protection line associated with said second group of working transmission lines, said second protection line being capable of exchanging data with the second remote node in the network;
• a control unit operative to monitor said first and second groups of working transmission lines and,
• a) upon detection of a data transmission impairment of a first type over any one of the lines in said first group of working transmission lines, invoke a first protection switch event causing re-routing of optical signals from the working transmission line on which the data transmission impairment of the first type has been detected to said first protection line;
• b) upon detection of a data transmission impairment of a second type between said local node and the first remote node, invoke a second protection switch event causing re-routing of optical signals from a particular working transmission line of said first group of working transmission lines to said second protection line.