Integrated ring-mesh network

• US 6,654,379 B1
• Filed: 10/07/1999
• Issued: 11/25/2003
• Est. Priority Date: 10/08/1998
• Status: Expired due to Term

• Current Assignee: Telecommunications Research Laboratories
• Original Assignee: Telecommunications Research Laboratories
• Inventors: Martens, Randy G., Grover, Wayne D.
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): George, Keith M.
• Application Number:
  US09/414,474
• Time in Patent Office: 1,510 Days
• Field of Search: 370/222, 370/223, 370/254, 370/258, 370/406, 370/407, 370/408, 370/224, 709/251, 709/252
• US Class Current: 370/406
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0241 Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
• CPC Class Codes: H04J 14/0284 WDM mesh architectures
• CPC Class Codes: H04J 14/0287 Protection in WDM systems
• CPC Class Codes: H04J 2203/0042 Ring
• CPC Class Codes: H04J 2203/0055 Network design, dimensioning, topology or optimisation
• CPC Class Codes: H04J 2203/006 Fault tolerance and recovery
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 2011/0081 Fault tolerance; Redundancy; Recovery; Reconfigurability
• CPC Class Codes: H04Q 2011/0092 Ring
• CPC Class Codes: H04Q 2011/0098 Mesh

Abstract

Whether in a SONET or a dense-WDM (DWDM) transport environment, we can expect to see a continuance of the two main survivable architectures: ring and mesh. The differing advantages of these technologies has allowed both of them to find applications, although they are usually deployed and operate quite separately. To date, the problem of optimally combining ring and mesh technologies into a single integrated transport design remains largely unstudied. This patent document presents a planning principle and related optimization theory to strategically embed rings into a mesh network, with the purpose of obtaining a lower total design cost than that of either a pure-mesh or pure-ring design. The new design approach is based on a recently developed insight into the nature of spare capacity requirements in a mesh-restorable network. So-called “forcer” analysis identifies the spans that drive the dimensioning of spare quantities in the network. The main hypothesis is that strategic placement of rings onto these spans, can result in mesh sparing relief that more than pays for the cost of the rings. However, the very large number of possible ring placements and sizes, makes this a difficult combinatorial optimization problem. Both heuristic and Integer Programming approaches were used to solve the problem. Results show cases of hybrid designs that are 5 to 25% less costly than that of a pure mesh design, depending on the test network and the relative mesh-ring technology costs. The Integer Programming method worked well for networks with fewer nodes and spans, while the heuristic was needed to obtain good solutions for relatively larger networks.

Claims

1. A method of improving sparing efficiency in a telecommunications network in which the telecommunications network has at least one forcer span that has a deleterious effect on sparing efficiency and in which the nodes in at least part of the telecommunications network are configured as a mesh network, the method comprising the steps of:

identifying a forcer span in the telecommunications network;

finding a placement of a ring in the telecommunications network that reduces the deleterious effect of the forcer span; and

integrating the ring into the telecommunications network.

2. The method of claim 1, in which integrating the ring into the network makes the forcer span a non-forcer span.

3. The method of claim 2, in which finding a placement of a ring that reduces the deleterious effect of the forcer span comprises evaluating plural ring placements based on the cost of placing each ring in the network.

4. The method of claim 3, in which a ring is selected for placement in the network that is the most cost effective of the ring placements evaluated.

5. The method of claim 3, in which integer programming is used to evaluate the ring placements.

6. The method of claim 3, in which a heuristic is used to evaluate the ring placements.