Ethernet Ring Protection node

A redundant ring node comprising:

• a first line card used to implement a ring node, the first line card comprising:
• a first front port serving as a first ring port of two ring ports defined for ring nodes supporting a ring protection protocol, and
• a first state machine implementing a state machine consistent with the ring protection protocol;
• a second line card used to implement the ring node, the second line card comprising:
• a second front port serving as a second ring port of the two ring ports defined for ring nodes supporting the ring protection protocol, and
• a second state machine also implementing a state machine consistent with the ring protection protocol;
• and
• a backplane providing communication infrastructure between multiple line cards residing at the ring node
• a preservation module residing at the second line card and operable to:
• preserve a first matched message received at the second virtual port so that a second update module pertaining to the second state machine can determine whether to updated the second state machine in response to the first matched message, where a matched message is defined as a message carrying a node identification value assigned to a node providing the message that matches a node identification value assigned to the second line card;
• and
• allow a second matched message to be discarded without a response from the second state machine where the second matched message arrives at the second ring port.

A method for implementing a redundant node supporting a ring protection protocol comprising:

• implementing a ring-protection-protocol state machine on each of two different line cards residing at a ring node supporting a ring protection protocol, a front port of each line card providing one of two ring ports defined for the ring node by the ring protection protocol;
• updating a first ring-protection-protocol state machine on a first line card of the two line cards to an updated state;
• passing a message from a first virtual port of the first line card over a backplane of the ring node to a second virtual port of the second line card;
• and
• updating a second ring-protection-protocol state machine on the second line card of the two line cards to the updated state in response to the message received at the second virtual port such that the first state machine and the second state machine are synchronized as a common virtual state machine with respect to the ring node;
• monitoring an inter-card communication link from the first virtual port of the first line card over the backplane to the second virtual port of the second line card for a failure;
• closing at least one of the first virtual port and the second virtual port in response to a failure;
• and
• sending a failure message out at least one of the two ring ports of the ring node, the failure message indicating a need to open a ring protection link blocked to prevent a loop in a ring of nodes to which the ring node pertains.

A method for implementing a redundant node supporting a ring protection protocol comprising:

• implementing a ring-protection-protocol state machine on each of two different line cards residing at a ring node supporting a ring protection protocol, a front port of each line card providing one of two ring ports defined for the ring node by the ring protection protocol;
• updating a first ring-protection-protocol state machine on a first line card of the two line cards to an updated state;
• passing a message from a first virtual port of the first line card over a backplane of the ring node to a second virtual port of the second line card;
• updating a second ring-protection-protocol state machine on the second line card of the two line cards to the updated state in response to the message received at the second virtual port such that the first state machine and the second state machine are synchronized as a common virtual state machine with respect to the ring node;
• and
• redirecting traffic previously passing through a ring port of the ring node maintained by a failed line card to pass through a remaining ring port of the two ring ports defined for the ring node under ring protection control provided by a surviving state machine residing on a surviving line card maintaining the remaining ring port and then to pass across the backplane of the ring node and out an additional front port of the ring node to a client node external to a ring of nodes to which the ring node pertains.