Nortel Networks Corporation

Peter William Phelps

Evert De Boer

David Charles Steele

Louis Rene Pare

Joseph Olajubu

Robert Caporuscio

Evert E deBoer

Louis-Rene Pare

Stephen Wilson

Paul Charron

Johnny Leung

Nicola Benvenuti

Richard Trudel

LeRoy Anthony Pick

James R Mattson

Darryl C Ryan

Brett Caldwell

Dave Langridge

Bruce E Dunn

Gary L Swinkels

Evert De Moer

Louis R Par&eacute;

A method for providing grades of service to unprotected traffic on an optical network that provides protection channels associated with working channels, defines a linearly ordered set of protection switch request priorities, and two or more grade of service priorities, and uses those priorities to enforce a protection access policy. The unprotected traffic may be of a high priority, approximating non-pre-emptable unprotected traffic (NUT); of low priority, like extra traffic; or may be of an intermediate priority between the two. This allows data transport providers to offer different unprotected transport services at different rates on protected links, in which the different unprotected transport services are associated with different probabilities of pre-emption.

Method and apparatus for providing grades of service for unprotected traffic in an optical network

A data communication apparatus having a plurality of working ports for exchanging data traffic with a network element and at least one protection port. The communication apparatus also has a protection switching functional element to switch data traffic from a failed working port to the at least one protection port. The protection switching functional element is capable to acquire either one of a first mode of operation and a second mode of operation. The first mode of operation is an 1:Q mode using a single protection port where Q is the number of working ports and Q is equal or greater than 1. The second mode of operation is an M:N mode where M is the number of protection ports and N is the number of working ports, where M and N are greater than 1.

Data communication apparatus with a dual mode protection switching system

It is proposed that currently unused portions of transport overhead in frames sent on a high-speed outgoing channel be used to carry error count information from each of four low-speed input channels. At a 4:1 combiner, error monitoring bytes are extracted from transport overhead of frames received on each of the four input channels. Error counts are determined and accumulated for each input channel before being passed to a transport overhead generator for the outgoing channel, where they are inserted as bit patterns in unused portions of the transport overhead. At a receiving demultiplexer, the error counts are extracted from the transport overhead of incoming frames. The extracted error counts are then used to alter the error monitoring bytes included in the transport overhead of frames sent on each of four outgoing channels such that, at the far end of those outgoing channels, a correct number of errors for the three part path may be determined.

Transparent error count transfer method and apparatus

A method and corresponding network element configuration for delivering communications services between first and second survivable rings, each comprising a respective plurality of network elements, at least two of which are common to both rings. For each particular service, one of the common network elements is designated as a primary gateway node and another as a secondary gateway node. A primary inter-ring connection is established for the particular service by a switch at the primary gateway node, but no inter-ring connection is established at the secondary gateway node. The secondary gateway node comprises a controller for monitoring the status of the primary gateway node and establishing a new inter-ring connection for delivery of the service upon detecting a failure of the primary gateway node. This provides survivable inter-ring traffic which is bandwidth-efficient and with a low switching delay.

Method and apparatus for ensuring survivability of inter-ring traffic

The working fibre and protection fibre between pairs of nodes are shared between adjacent rings in a network, such that working traffic on the working fibre between the pair of nodes can be protected by the ring architecture of either of adjacent rings. A network management system routes signals across the network and dictates which rings within the network provide protection for the signal route. The ring structure enables protection for signal traffic on a ring to be protected by the ring protocols, providing rapid protection switching. It is also possible to select the location of protection bandwidth for a signal path across the network. In this way, protection bandwidth is shares and can also be configured to optimise the use of the total available protection bandwidth.

Optical communications network

A method and corresponding network element configuration for delivering communications services between first and second survivable rings, each comprising a respective plurality of network elements, at least two of which are common to both rings. For each particular service, one of the common network elements is designated as a primary gateway node and another as a secondary gateway node. A primary inter-ring connection is established for the particular service by a switch at the primary gateway node, but no inter-ring connection is established at the secondary gateway node. The secondary gateway node comprises a controller for monitoring the status of the primary gateway node and establishing a new inter-ring connection for delivery of said service upon detecting a failure of the primary gateway node. This provides survivable inter-ring traffic which is bandwidth-efficient and with a low switching delay.

The present invention relates to a local node for use in a synchronous optical network ring. The local node includes a group of working transmission lines and a protection line, for connecting to a remote node. The local node further includes a control unit for monitoring the working transmission lines and, upon detection of a data transmission impairment over a particular working transmission line, invoking a protection switch event causing re-routing of optical signals from the particular working transmission line to the protection line. Should the control unit detect simultaneous data transmission impairments over two or more working transmission lines, the control unit will choose to protect a particular working transmission line on the basis of a user-defined priority scheme.

Method and apparatus for providing a more efficient use of the total bandwidth capacity in a synchronous optical network

The present invention provides a method of deactivating working fibers in an existing optical ring network or system for a cost-effective and efficient allocation of the fiber resources available in the ring network. When a working fiber is underutilized in an existing ring network, the traffic scheduled for transmission thereon is re-routed around the network away from the fiber and lockouts are applied to prevent the fiber to be removed from being protected. The fiber and associated connecting equipment thus become unused and unnecessary for traffic carrying purposes and can then be deactivated. By eliminating the need for working fibers and associated optics equipment on spans where traffic is low or non-existent, the invention can provide fiber capacity savings of up to fifty percent on each span while retaining full protection usage. According to the invention, the unused fibers and equipment can be removed or alternatively be re-provisioned for use in other network configurations to provide a cost-effective and efficient allocation of the resources available in the network.

Method of deactivating working fiber resources in optical ring networks

The present invention consists of a method of deactivating protection fiber resources in an existing optical interconnected ring network or system. The invention uses 1:N protection principles to provide a single protection path on spans interconnecting nodes common to two or more optical rings. With the sharing of a protection fiber or channel on spans interconnecting common nodes, the present invention eliminates the need for multiple protection paths on these spans and provides substantial fiber capacity savings. According to the invention, the protection fibers and equipment deactivated can be removed or alternatively re-provisioned to provide a cost-effective and efficient allocation of the resources available in the network.

Method of deactivating protection fiber resources in optical ring networks

The matched nodes provide protection for a failure in the connection between two bidirectional line switched rings. They use a secondary path in case of a primary path failure. The secondary path is set aside in either the working or protection bandwidth of the rings, thus wasting resources. The invention uses a dedicated secondary path between the primary and secondary nodes. With the invention, no ring protection mechanisms are compromised and the ring bandwidth is not wasted. Middle nodes also realize full add/drop capabilities.

Optical ring protection having matched nodes and alternate secondary path

A line condition control (LCC) algorithm is disclosed that is implemented within a switching card that chooses, for information transmission, between working and protection fiber optic channels. The disclosed LCC algorithm ensures that a channel with an oscillating signal failure condition will be utilized instead of a channel with a solid signal failure condition. The LCC algorithm, input with an input line condition (ILC) corresponding to one of the fiber optic channels, outputs a corresponding output line condition (OLC) that is input to a decision algorithm within the switching card. The OLC is set to a signal degrade condition if either a protection oscillation control (POC) mechanism is activated or if a specified number of signal failure condition clearances are detected within a set time period which, in turn, activates the POC mechanism. Otherwise, the OLC is set equal to the ILC. A channel with a signal degrade condition will always be chosen by the decision algorithm over a channel with a signal failure condition and therefore, a channel with an oscillating signal failure condition that has its OLC set to a signal degrade condition will be chosen over another channel that has a solid signal failure condition.

Signal degrade oscillation control mechanism

The matched nodes provide protection for a failure in the connection between two bidirectional line switched rings. They use a secondary path in case of a primary path failure. The secondary path is set aside in either the working or protection bandwidth of the rings, thus wasting resources. The invention uses inter-ring protection mechanisms which do away with a specifically set aside secondary path between the primary and secondary nodes.

Optical inter-ring protection having matched nodes

The present invention relates to a switching node for use in a synchronous optical network ring, where the ring is transporting data divided into first size blocks, for example OC-192 optical signals, characterized by data blocks of size 192. The switching node includes several primary receive and send connections, for receiving and transmitting inter-ring optical signals divided into second size blocks, for example OC-48 optical signals, characterized by data blocks of size 48. The switching node further includes a secondary receive and send connection for receiving and transmitting intra-ring optical signals divided into first size blocks. A critical component of the switching node is the main controller, responsible for routing incoming intra-ring first size blocks towards a primary send connection. The main controller divides a first size block into smaller second size blocks, observes the second size blocks for the presence of concatenated data and, in the case where there is presence of concatenated data, routes the second size block as a single unit towards the adjacent network ring. In the case where there is absence of concatenated data, the routing controller routes the group of data forming the second size block as independent data elements towards the adjacent network ring.

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Nepean, Canada

Peter William Phelps