Method and apparatus for processing protection switching mechanism in optical channel shared protection rings
View Patent ↗A method for merging protection switching messages in an optical network enables a control of the amount of message bandwidth used for sending protection switching messages. A method for performing protection switching in an optical network does so in an optimal manner by performing the protection switching actions in the various nodes of a protection path in parallel rather than in sequence. To do so, a channel failure message is transmitted from an end node A in the optical network upon detecting a failure in a link in the optical network that includes the end node A. If a failure can be detected at both end nodes, the channel failure messages are transmitted from both end nodes the moment they detect failure without any further waiting. Upon receiving the first channel failure message regardless its originating end node, switching actions in intermediate nodes are initiated. The channel failure messages are forwarded from the intermediate nodes to their corresponding next nodes before completing switching actions in the intermediate nodes. When receiving channel failure response messages, these messages are forwarded to a next node from the intermediate node only after switching actions are complete in the intermediate node.
1. A method for processing protection signaling messages in a node in an optical network, comprising:
treating protection signaling messages with a highest priority when there are resource contentions with other types of signaling messages;
treating all protection signaling messages in a single first-in-first-out fashion if there are multiple protection signaling messages waiting to be processed in a single node;
merging two channel failure response messages, each of said two channel failure response messages generated upon receipt of a corresponding channel failure message, destined for a same next node into one single combination channel failure response message in a single node; and
transmitting the single combination channel failure response message to the same next node in the optical network.
2. The method according to claim 1 , further comprising:
merging two channel failure messages destined for a same next node into one single combination channel failure message in a single node; and
transmitting the single combination channel failure response message to the same next node in the optical network.
3. The method according to claim 1 , further comprising responding to a failure in the optical network by:
transmitting, upon detection of the failure, a first channel failure message from a first end node;
transmitting, upon detection of said failure, a second channel failure message from a second end node;
transmitting, upon receipt of the second channel failure message, a first channel failure response message at the first end node;
transmitting, upon receipt of the first channel failure message, a second channel failure response message at the second end node;
switching working traffic to a first protection channel upon receipt of the second channel failure response message at the first node;
switching working traffic to a second protection channel upon receipt of the first channel failure response message at the second node;
forwarding, at one or more intermediate nodes, the first or second channel failure response messages only after completing protection switching actions in the one or more intermediate nodes.
4. The method according to claim 3 , further comprising:
initiating a timer upon transmitting from the first end node the first channel failure message, and if the timer expires before the first end node receives the second channel failure response message, then re-transmitting the first channel failure message; and
after a specified number of re-transmissions of the first channel failure message, if an end node still cannot receive a channel failure response message back before timer expires, then declaring a protection switching failure.
5. A method for processing protection signaling messages in a node in an optical network, comprising:
treating protection signaling messages with a highest priority when there are resource contentions with other types of signaling messages;
treating all protection signaling messages in a single first-in-first-out fashion if there are multiple protection signaling messages waiting to be processed in a single node;
merging two channel failure messages, each of said two channel failure messages generated upon detection of a corresponding failure between endpoint nodes, destined for a same next node into one single combination channel failure message in a single node; and
transmitting the single combination channel failure message to the same next node in the optical network.
6. A method for processing channel failure messages in an optical network comprising:
merging a plurality of channel failure messages into one combination channel failure message as long as all of the plurality of channel failure messages travel in a same direction, wherein each of said plurality of channel failure messages includes channel information requesting initiation of protection switching actions for a channel; and
stripping out of the combination channel failure message corresponding channel information upon arrival at a destination end node corresponding to the channel information,
wherein the combination channel failure message remaining after stripping out the corresponding channel information continues to a next node.
7. The method according to claim 6 , further comprising initiating protection switching for all embedded circuits in an intermediate node upon receiving a combination channel failure message.
8. The method according to claim 7 , further comprising forwarding the combination channel failure message to a next node before completing protection switching for all embedded circuits in the intermediate node.
9. The method according to claim 8 , further comprising forwarding the combination channel failure message from the intermediate node to the next node immediately upon receipt and prior to initiating any protection switching actions for any embedded circuits in the intermediate node.
10. The method according to claim 6 , further comprising discarding the combination channel failure message only after the combination channel failure message has been received by all corresponding end nodes of embedded circuits.
11. A method for operating an optical network, which is composed of optical channel shared protection rings including one or more optical add-drop ring multiplexers, two endpoint nodes, one or more intermediate nodes and a protection path, comprising:
initiating at a first endpoint node protection switching by generating a first channel failure message and transmitting the first channel failure message toward the second endpoint node along a protection path upon detection of a failure;
initiating at a second endpoint node protection switching by generating a second channel failure message and transmitting the second channel failure message toward the first endpoint node along a protection path upon detection of a failure,
wherein each of said first channel failure message and said second channel failure message includes channel information requesting initiation of protection switching actions for a channel;
within each node on the protection path, including both end nodes and said one or more intermediate nodes:
upon receiving one of either the first or second channel failure messages, initiating protection switching actions for both directions and forwarding the one received channel failure message to a next node uni-directionally before protection switching actions are complete; and
upon receiving the other of either the first or second channel failure messages, forwarding the other received channel failure message to a next node uni-directionally;
merging a plurality of channel failure messages into one combination channel failure message as long as all of the plurality of channel failure messages travel in a same direction; and
stripping out of the combination channel failure message corresponding channel information upon arrival at a destination end node corresponding to the channel information,
wherein the combination channel failure message remaining after stripping out the corresponding channel information continues to a next node.
12. The method according to claim 11 , further comprising:
initiating a corresponding channel failure response message at each of the first and second end nodes if and only if:
protection switching actions for both directions are completed; and
a channel failure message that is originated from the other end node has arrived.
13. The method according to claim 12 , further comprising:
forwarding the corresponding channel failure response messages in the intermediate nodes only when protection switching actions for both directions are completed.
14. The method according to claim 12 , further comprising:
upon receiving a first channel failure response message, determining whether associated protection switching actions for both directions are completed;
if the determination is that protection switching actions for both directions are complete, then forwarding the received first channel failure response message to a next node;
if the determination is that protection switching actions for both directions are not complete; waiting until associated protection switching actions for both directions are completed and then forwarding the received first channel failure response message to a next node;
upon receiving a second channel failure response message, forwarding the second received channel failure response message to a next node.
15. The method according to claim 14 , further comprising upon the first end node receiving a channel failure response message to a first channel failure message generated by said first end node, the first end node switches all working traffic to the protection channel.
16. The method according to claim 15 , further comprising upon the second end node receiving a channel failure response message to a second channel failure message generated by said second end node, the second end node switches all working traffic to the protection channel.