Protection for Optical Transport Network Using Operational Status of Dual Homed Attachment Circuits

Patent metadata

Field	Value
Publication number	US-2016006502-A1
Application number	US-201314760757-A
Country	US
Kind code	A1
Filing date	Apr 25, 2013
Priority date	Jan 25, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

For protecting traffic from a source client entity (CE 1 ) to a destination client entity (CE 2 ) via an optical transport network and attachment circuits at ingress (A,B) and egress (C,D) nodes, there are multiple paths within the OTN, and the attachment circuits are dual homed. By sending ( 120 ) an indication of operational status of the dual homed attachment circuits within overhead associated with the traffic and sent with the traffic through the network, a selection can be made ( 130 ) of which of the provided paths and attachment circuits to use for the traffic, based on the indicated operational status, and on OTN fault detection, to protect against a fault. Thus protection can extend across the edge nodes without interworking of separate protection schemes and without a control plane. Traffic flows can be multiplexed at the ingress, with the indication in the overhead having separate indications for each of the traffic flows.

First claim

1 . A method of protecting traffic in a communications network, the communications network providing paths for the traffic extending from a source client entity to a destination client entity via an optical transport network, providing at least one attachment circuit for coupling the source client entity to corresponding ingress nodes of the optical transport network, and providing at least one attachment circuit at the egress, for coupling corresponding egress nodes of the optical transport network to the destination client entity, the attachment circuits comprising dual homed attachment circuits at least at the ingress nodes, and the paths comprising paths within the optical transport network, to couple respective pairs of the ingress and egress nodes, the method having steps of:
sending through the optical transport network an indication of operational status of at least one of the dual homed attachment circuits, the indication being sent within overhead associated with the traffic and sent with the traffic, and at a node of the optical transport network, selecting which of the provided paths and attachment circuits to use for the traffic, based on the indication of operational status of the attachment circuits sent through the optical transport network, to protect the traffic against a fault in the attachment circuit and against a fault in the optical transport network.

2 . A method of protecting traffic in a communications network, the communications network providing paths for the traffic extending from a source client entity to a destination client entity via an optical transport network, providing at least one attachment circuit for coupling the source client entity to corresponding ingress nodes of the optical transport network, and providing at least one attachment circuit at the egress, for coupling corresponding egress nodes of the optical transport network to the destination client entity, the attachment circuits being dual homed attachment circuits at least at the ingress nodes, and the paths comprising paths within the optical transport network, to couple respective pairs of the ingress and egress nodes, the method having steps of:
at an ingress node inserting an indication of operational status of at least one of the dual homed attachment circuits into overhead associated with the traffic, and sending the overhead with the indication within, with the traffic, to other nodes along the paths.

3 . A method of protecting traffic in a communications network, the communications network providing paths for the traffic extending from a source client entity to a destination client entity via an optical transport network, providing at least one attachment circuit for coupling the source client entity to corresponding ingress nodes of the optical transport network, and providing at least one attachment circuit at the egress, for coupling corresponding egress nodes of the optical transport network to the destination client entity, the attachment circuits being dual homed attachment circuits at least at the ingress nodes, and the paths comprising paths within the optical transport network, to couple respective pairs of the ingress and egress nodes, the method having steps of:
reading at a node of the optical transport network an indication of operational status of a corresponding one of the dual homed attachment circuits, the indication being within overhead associated with the traffic and sent with the traffic, and selecting which of the provided paths and attachment circuits to use for the traffic, based on the indication of the operational status of the attachment circuits sent through the optical transport network, to protect the traffic against a fault in the attachment circuit and against a fault in the optical transport network.

4 . The method of claim 1 , the traffic comprising at least two traffic flows each having a respective source client entity and destination client entity, the at least two traffic flows having their own dual homed attachment circuits and sharing the same paths through at least some of the optical transport network, wherein the indication sent within the overhead comprises indications of operational status of the respective attachment circuits of the at least two traffic flows.

5 . The method of claim 4 , having the step of combining the at least two traffic flows at least one of their ingress nodes, for transmission through the optical transport network, and optionally, the at least two traffic flows are combined by multiplexing.

6 . The method of claim 4 , where the at least two traffic flows have been combined for transmission through the optical transport network, and the method having the step of separating the combined traffic flows at their egress node, and optionally, the at least two traffic flows are combined by multiplexing for transmission.

7 . The method of claim 4 having the step of controlling, for a respective one of the combined traffic flows, which of its dual homed attachment circuits at the ingress has an active status, based at least on an indication of a fault in the paths used by that respective traffic flow, and on an indication sent back through the optical transport network, of operational status of dual homed attachment circuits at the egress for that respective traffic flow.

8 . The method of claim 1 , having the step of sending the traffic flows from ingress to egress of the optical transport network in a data container of a type which is normally not terminated at any intermediate nodes of the optical transport network, without requiring specific configuration of such intermediate nodes to ensure the data container is not terminated.

9 . The method of claim 1 , having the step of receiving an indication of a fault in the paths in the optical transport network and the selecting step being based also on the fault indication.

10 . The method of claim 1 , the operational status comprising at least one of an indication of a protection status, and an indication of a fault status.

11 . The method of claim 1 , where the dual homing is at the ingress nodes, and where there are paths from the ingress nodes to the egress node, and the sending step comprises sending the indication forwards along the paths, to the egress node, and the step of selecting comprises selecting at the egress node which of the paths to use for the traffic according to the indications received.

12 . The method of claim 1 , where the dual homing is at both the ingress nodes and the egress nodes, and there are paths from each of the ingress nodes to more than one of the egress nodes, the selecting step comprising selecting which egress node to use for the traffic, according to the operational status of the attachment circuits.

13 . The method of claim 1 , where there is dual homing at the egress nodes, the sending step comprising feeding back the indication along the paths, to other nodes along the paths.

14 . The method of claim 1 , the communications network providing paths for traffic in both directions between the source and destination client entities, and having the step of sending in both directions the indications of operational status in overhead associated with the traffic and sent with the traffic.

15 . A computer program on a computer readable medium having instructions which when executed by a processor cause the processor to control the steps of the method of claim 1 .

16 . A node configured to operate at least as an ingress node of an optical transport network for use in a communications network, the communications network being arranged to provide paths for

Assignees

• Ericsson Telefon Ab L M

Inventors

• Fulignoli Annamaria
• Corti Andrea
• Lanzone Sergio

Classifications

• H04J2203/0028

  Local loop · CPC title

• H04J3/14 Primary

  Monitoring arrangements {(for SDH/SONET rings H04J3/085)} · CPC title

• H04J2203/006

  Fault tolerance and recovery · CPC title

• H04B10/032 Primary

  using working and protection systems {(H04J14/0287 takes precedence)} · CPC title

• H04B10/27

  Arrangements for networking · CPC title