Bidirectional line switched partial rings, mesh networks, and methods of operation

A method of allocating protection bandwidth in a mesh network having a first ring comprised of a first plurality of nodes coupled by a first plurality of spans and a second ring comprised of a second plurality of nodes coupled by a second plurality of spans, the first and second rings sharing a common section comprising least two common nodes coupled by at least one span, the method comprising:

• operating the first ring as a bi-directional line switched ring that includes the first plurality of nodes and the common nodes, the first ring having working and protection bandwidth through each of the first plurality of spans and the at least one span between the common nodes, wherein the first ring has a symmetrical arrangement of working and protect ports;
• operating the second ring as a bi-directional line switched ring having working traffic in the second plurality of spans exclusive of the at least one span between the common nodes, the second ring having protection traffic through the second plurality of spans and the at least one span between the common nodes responsive to a protection switching event for the second ring and adjusting optical power of the common section to account for protection traffic of the second ring traversing the common section in the protection mode of the second ring, wherein the second ring has an asymmetrical arrangement of working and protect ports such that the second ring has at least one unconfigured working port that ignores or rejects a received switch command and does not perform a commanded span or ring switch;
• wherein the common section is provisioned such that it provides protection for both the first and second rings.

A bi-directional line switched mesh network, comprising:

• a first bi-directional line switched ring including a plurality of nodes coupled by spans;
• a second bi-directional line switched ring including a plurality of nodes coupled by spans;
• the second bi-directional line switched ring sharing a common section with the first bi-directional line switched ring, the common section including at least two common nodes and at least one common span;
• the second bi-directional line switched ring having no working traffic traversing the common span of the common section during a normal mode of operation for the second bi-directional line switched ring, and wherein the second bi-directional line switched ring has at least one unconfigured working port that ignores or rejects a received switch command and does not perform a commanded span or ring switch;
• and
• the second bi-directional line switched ring sharing protection bandwidth with the first bi-directional line switched ring along the at least one common span of the common section during a protection mode of operation for the second bi-directional line switched ring;
• wherein at least one of the nodes comprises:
• an internode communication module for receiving messages indicative of whether the second ring is operating in the normal mode or the protection mode;
• and
• an optical amplifier whose amplification can be adjusted by a power management module residing in an administrative complex of the node;
• the power management module adjusting the optical amplification level of the optical amplifier to account for protection traffic of the second ring traversing the common section in the protection mode of the second ring.

An optical communications system, comprising:

• a first optical network including a plurality of first nodes configured as a first bi-directional line switched partial ring, wherein the first bi-directional line switched partial ring has a symmetrical arrangement of working and protect ports;
• a second optical network including a plurality of second nodes configured as a second bi-directional line switched partial ring, wherein the second bi-directional line switched partial ring has an asymmetrical arrangement of working and protect ports such that the second ring has at least one unconfigured working port that ignores or rejects a received switch command and does not perform a commanded span or ring switch;
• a plurality of shared nodes operatively interconnecting said first and second optical networks, said shared nodes being shared by said first and second optical networks;
• at least one shared optical span operatively interconnecting said shared nodes, said shared optical span providing shared optical capacity shared by said first and second optical networks;
• said shared nodes and said shared span being configured to share optical protection capacity between the first and second optical networks;
• wherein said at least one shared optical span is provisioned such that it provides protection for both said first and second optical networks;
• and
• wherein at least one of said shared nodes comprise:
• an internode communication module for receiving messages indicative of whether the second optical network is operating in the normal mode or the protection mode;
• and
• an optical amplifier whose amplification can be adjusted by a power management module residing in an administrative complex of the node;
• the power management module adjusting the optical amplification level of the optical amplifier to account for protection traffic of the second optical network traversing the at least one shared optical span in the protection mode of the second optical network.