Ethernet Ring Protection node

Patent metadata

Field	Value
Publication number	US-9319240-B2
Application number	US-201314035035-A
Country	US
Kind code	B2
Filing date	Sep 24, 2013
Priority date	Sep 24, 2013
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

Systems and methods are disclosed for providing redundancy in a network node implementing a ring protection protocol. Each of the two ring ports connecting the node to other nodes in a ring supporting the protocol may be maintained by a separate line card. Should one line card fail, traffic passing through the node may be redirected through the remaining ring port under the control of the surviving state machine. The two state machines may be coordinated over the backplane of the node to maintain a common state, making them transparent to other nodes. Additionally, the backplane link between the state machines may be monitored for failures that may be addressed with messages used to respond to general ring failures and by assigning one state machine to block a ring port upon recovery to prevent a loop within the ring until the ring protection link can be blocked.

First claim

The invention claimed is:

1. 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;
an inter-card communication link implemented over the backplane between a first virtual port at the first line card and a second virtual port at the second line card;
a first update module of the first state machine operable to update the first state machine according to the ring protection protocol and in response to a state message arriving at the first ring port;
a forwarding module residing on the first line card and operable to forward the state message through the first virtual port and over the inter-card communication link supported by the backplane to the second state machine residing on the second line card; and
a second update module of the second state machine operable to respond to the state message received at the second virtual port according to the ring protection protocol as though the state message were received at the second ring port so that the second update module updates the second state machine to the updated state such that the first state machine and the second state machine share a common state for the ring node.

2. The redundant ring node of claim 1 , wherein at least one of the first state machine and the second state machine include an internal-port blocking module operable to at least one of:
block a corresponding virtual port, the corresponding virtual port being the first virtual port where the internal-port blocking module pertains to the first state machine and the second virtual port where the internal-port blocking module pertains to the second state machine, in response to a failure of the inter-card communication link; and
unblock the corresponding virtual port in response to at least one of:
a recovery of the inter-card communication link, and
a link-up message.

3. The redundant ring node of claim 1 , further comprising a messaging module for at least one of the first state machine and the second state machine operable to at least one of:
send a failure message out a corresponding ring port, the corresponding ring port being the first ring port where the messaging module pertains to the first state machine and the second ring port where the messaging module pertains to the second state machine, the failure message defined by the ring protection protocol to respond to a failure at a link maintained between ring ports of adjacent ring nodes within a ring defined by the ring protection protocol, in response to a failure at the inter-card communication link; and
send a recovery message out the corresponding ring port, the recovery message defined by the ring protection protocol to respond to a recovery of a link maintained between ring ports of adjacent ring nodes, in response to a recovery of the inter-card communication link.

4. The redundant ring node of claim 1 , further comprising:
a set of master-role actions performed by one of the first state machine and the second state machine; and
a set of slave-role actions performed by the one of the first state machine and the second state machine not performing the set of master-role actions.

5. The redundant ring node of claim 4 , wherein the set of master-role actions comprises blocking a corresponding ring port in response to a recovery of the inter-card communication link, the corresponding ring port being the first ring port where the set of master-role actions is performed by the first state machine and the second ring port where the set of master-role actions is performed by the second state machine.

6. The redundant ring node of claim 5 , wherein the set of master-role actions further comprises:
unblocking the corresponding ring port in response to one of:
expiration of a recovery timer where the ring node is an owner node responsible for a ring protection link as defined by the ring protection protocol, and
receipt of a root-blocked message where the ring node is not an owner node; and

sending a link-up message over the inter-card communication link after blocking the corresponding ring port to prompt a state machine to unblock a corresponding virtual port at a remote end of the inter-card communication link.

7. The redundant ring node of claim 1 , further comprising at least one additional line card residing at the ring node with at least one front port linked to a client node outside of a ring to which the ring node belongs, the additional line card communicatively coupled to both the first line card and the second line card over the backlink.

8. 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.

9. 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 vir

Assignees

• Ciena Corp

Inventors

• Nahlous Paul Simon
• Subramaniam Balaji

Classifications

• H04L41/0668

  by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure · CPC title

• H04L12/437 Primary

  Ring fault isolation or reconfiguration {(for SDH/SONET ring networks H04J3/085)} · CPC title

• H04L45/28

  using route fault recovery · CPC title

• H04L45/22

  Alternate routing · CPC title

• H04L43/0811

  by checking connectivity · CPC title