Method and apparatus for operation, protection, and restoration of heterogeneous optical communication networks

An optical network comprising,

• a plurality of at least three nodes, each given node including (a) an optical network interface for coupling to two other nodes in the network, and (b) a terminal interface for coupling to terminal equipment associated with the given node, and
• a corresponding plurality of bidirectional optical links connecting the plurality of nodes in a ring topology to provide bidirectional communication between adjacent pairs of nodes on the network, each adjacent pair of nodes being connected by an intervening one of the optical links, the ring being considered to define two opposite directions arbitrarily designated upstream and downstream so that each node has upstream and downstream adjacent nodes,
• wherein:
• each optical link has a bidirectional working link and a bidirectional protection link;
• each node's network interface includes first and second network working ports and first and second network protection ports;
• each node's terminal interface includes first and second terminal working ports and first and second terminal protection ports;
• each node's first working and protection ports are coupled to the node's upstream adjacent node's second working and protection ports, respectively;
• each node has an optical switching assembly having at least one optical switching element, the optical switching assembly having at least a normal state coupling the node's associated terminal equipment to the node's first and second network working ports through the node's first and second terminal working ports;
• the network is a heterogeneous network wherein
• at least a first working link between first and second nodes of the plurality of nodes is configured to support communications at a first bandwidth,
• terminal equipment associated with the first and second nodes is capable of sending and receiving communications at the particular first bandwidth on the first working link, and
• terminal equipment associated with at least one of the nodes is capable of sending and receiving communications at a second bandwidth that is less than the first bandwidth, but is not capable of sending and receiving communications at the first bandwidth;
• all the protection links are configured to support communications at the first bandwidth;
• the first node's optical switching assembly has a first switching state that selectively couples the first node's associated terminal equipment to the first node's first network protection port through the first node's second terminal working port;
• the second node's optical switching assembly has a second switching state that selectively couples the second node's associated terminal equipment to the second node's second network protection port through the second node's first terminal working port;
• and
• the optical switching assembly of each of at least those nodes other than the first and second nodes has a bypass state that selectively couples the node's first and second protection ports to a bypass path that bypasses the node's terminal interface, thereby allowing communications at the first bandwidth between the first and second nodes over the protection links other than the first protection link in the event that the first working and protection links become incapable of supporting communications at the first bandwidth between the first and second nodes.

An optical network comprising,

• a plurality of N nodes where N>2, each given node including an optical network interface for coupling to two other nodes in the network and a terminal interface for coupling to terminal equipment associated with the given node, and
• a plurality of N bidirectional optical links connecting the plurality of N nodes in a ring topology to provide bidirectional communication between adjacent pairs of nodes on the network, each adjacent pair of nodes being connected by an intervening one of the optical links, the ring being considered to define two opposite directions arbitrarily designated upstream and downstream so that each node has upstream and downstream adjacent nodes,
• wherein:
• each optical link has a bidirectional working link and a bidirectional protection link;
• each node's network interface includes a first working port, a second working port, a first protection port, and a second protection port;
• each node's first working and protection ports are coupled to the node's upstream adjacent node's second working and protection ports, respectively;
• the network is a heterogeneous network wherein
• at least the first working link is configured for multi-wavelength operation,
• the first and second nodes have terminal interfaces providing wavelength division multiplexing capability to support multi-wavelength operation on the first working link,
• at least one of the working links is not configured for multi-wavelength operation, and
• at least one of the nodes has a terminal interface that does not provide wavelength division multiplexing capability;
• all the protection links are configured for multi-wavelength operation;
• and
• each node includes at least one optical switching element to selectively couple the node's first and second protection ports to a bypass path that bypasses the node's terminal interface, thereby allowing multi wavelength communication between the first and second nodes over the protection links other than the first protection link in the event that the first working and protection links become incapable of supporting multi wavelength communication between the first and second nodes.

An optical switching node for use at nodes in a heterogeneous network, the network including terminal equipment connected by network links, the network links including

• at least one link between a pair of nodes having terminal equipment capable of terminating a first type of communications, and
• at least one link coupled to a node having terminal equipment that is capable of terminating a second type of communications but incapable of terminating the first type of communications,
• the optical switching node comprising:
• first and second sets of bidirectional working and protection network ports for coupling to respective first and second bidirectional network links;
• first and second sets of bidirectional working and protection terminal equipment ports for coupling to first and second portions of terminal equipment, each portion of terminal equipment for sending and receiving data to and from said first and second bidirectional network links;
• a set of switch elements connected to said sets of network and terminal equipment ports for establishing span and ring switching in the event of a failure in a link that is between nodes having terminal equipment capable of terminating a first type of communications.

An optical switching node for use at nodes in a heterogeneous network, the network including terminal equipment connected by network links, the network links including

• at least one multi-wavelength link between a pair of nodes having terminal equipment capable of terminating multi-wavelength communications, and
• at least one link coupled to a node having terminal equipment that is incapable of terminating multi-wavelength communications,
• the optical switching node comprising:
• first and second sets of bidirectional working and protection network ports for coupling to respective first and second bidirectional network links;
• first and second sets of bidirectional working and protection terminal equipment ports for coupling to first and second portions of terminal equipment, each set of terminal equipment for sending and receiving data to and from said first and second bidirectional network links;
• and
• a set of switch elements connected to said sets of network and terminal equipment ports for establishing span and ring switching in the event of a failure in a multi-wavelength link.