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"In-Skin Wavelength Division Multiplex (Wdm) Path Computation" in Patent Application Approval Process

July 8, 2014

By a News Reporter-Staff News Editor at Journal of Mathematics -- A patent application by the inventors SWINKELS, Gerard LEO (Ottawa, CA); LALONDE, Frederick James (Ottawa, CA); WILGOSH, Michael Stanley (Nepean, CA), filed on December 17, 2012, was made available online on June 26, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application has not been assigned to a company or institution.

The following quote was obtained by the news editors from the background information supplied by the inventors: "In modern optical communications networks it is common practice to implement a control plane (eg as defined in ITU-T recommendation G.8080) for network topology discovery and route computation. Typically, the control plane deploys various protocols that enable each node of the network to populate a respective topology database that may subsequently be used to compute end-to-end routes through the network. One such protocol is Open Shortest Path First (OSPF), although there are others. As is typical of network discovery and route computation protocols, OSPF defines various types of Link State Advertisement (LSA) messages, which may be flooded into the network by a node to convey network topology information to all of the other nodes in the network. Accordingly, a given node can use the information contained in received LSAs to populate and maintain its topology database.

"OSPF and similar topology discovery and route computation protocols are commonly referred to as 'in-skin', because the topology discovery and route computation functionality is distributed across the nodes of the network, rather than being localized in one or more central servers.

"A limitation of control-plane based protocols such as OSPF is that lower-cost network nodes often lack sufficient resources to store and process the volume of information that would be needed to enable extension of OSPF-like topology discovery and route computation functionality in the physical layer of the network. Furthermore, the volume of LSA-like messaging that would be needed to maintain an accurate view of the physical network would be burdensome for all but the most trivial of network topologies. Consequently, network operators typically utilize a centralized Path Computation Element (PCE) or server to compute end-to-end paths through the network physical layer.

"However, as networks grow in size and complexity, the use of a centralized PCE may become disadvantageous. A known alternative is to divide the network into two or more sub-domains, each of which is associated with a respective PCE. However, this arrangement can increase complexity of network management, and does not address the problem that separate topology discovery and route computation functions are performed by different systems in different layers of the network. Many network service providers would prefer a single 'in-skin' solution for all layers of the network.

"Techniques that enable 'in-skin' path computation through the physical layer of a communications network are therefore highly desirable."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "An aspect of the present invention provides a method of managing an optical communication network having a plurality of nodes, the plurality of nodes including at least one regeneration site. A respective Path Computation Element (PCE) function is instantiated and associated with each regeneration site in the network. Each PCE function maintains a reach table containing information of viable optical paths extending from transceivers of its regeneration site. The PCE function implements a Recursive Path Computation algorithm to compute end-to-end routes through a physical layer of the network.


"Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

"FIG. 1 is a block diagram illustrating a representative network in which methods of the present invention may be implemented;

"FIG. 2, is a block diagram illustrating a local region of the network of FIG. 1;

"FIGS. 3A-3C are flow-charts illustrating principal steps in a constrained forwarding algorithm;

"FIG. 4 is a flow-chart illustrating principal step of a method implemented by a source node in the network of FIG. 1;

"FIG. 5 is a flow-chart illustrating principal step of a Recursive Path Computation (RPC) algorithm implemented by a regeneration site in the network of FIG. 1; and

"FIGS. 6A-6C are block diagrams illustrating operation of the RPC of FIG. 4.

"It will be noted that throughout the appended drawings, like features are identified by like reference numerals."

URL and more information on this patent application, see: SWINKELS, Gerard LEO; LALONDE, Frederick James; WILGOSH, Michael Stanley. In-Skin Wavelength Division Multiplex (Wdm) Path Computation. Filed December 17, 2012 and posted June 26, 2014. Patent URL:

Keywords for this news article include: Patents, Algorithms.

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Source: Journal of Mathematics

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