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(12) United States Patent
(io) Patent No.: (45) Date of Patent:
US 7,133,359 B2 Nov. 7, 2006
(54) FAST RESTORATION MECHANISM AND
METHOD OF DETERMINING MINIMUM
RESTORATION CAPACITY IN A
(75) Inventor: Bernd X. Weis, Korntal (DE)
(73) Assignee: Alcatel, Paris (FR)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 1003 days.
(21) Appl. No.: 10/106,502
(22) Filed: Mar. 27, 2002
(65) Prior Publication Data
US 2003/0067867 Al Apr. 10, 2003
(30) Foreign Application Priority Data
Apr. 4, 2001 (DE) 101 16 835
Sep. 14, 2001 (EP) 01 440 302
(51) Int. CI.
(52) U.S. CI 370/222
(58) Field of Classification Search 370/216,
370/221,222, 223, 224 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
6,141,319 A 10/2000 Dighe et al. 2005/0243711 Al* 11/2005 Alicherry et al 370/216
FOREIGN PATENT DOCUMENTS GB 2 327 020 A 1/1999
W.D. Grover et al., 'Cycle-Oriented Distributed Preconfigureation: Ring-like Speed with Mesh-like Capacity for Self-planning Network Restoration', 1998 IEEE, pp. 537-543 * M. Alicherry et al., Pre-Provisioning Networks to Support Fast Restoration with Minimum Over-Build, IEEE INFOCOM 2004, pp. 1-11*
Banerjee A et al: "Generalized Multiprotocol Label Switching: An Overview of Routing and Mangaement Enhancements" IEEE Communications Magazine, IEEE Service Center. Piscataway, N.J., US, vol. 39, No. 1, Jan. 1, 2001, pp. 144-150.
* cited by examiner
Primary Examiner—Melvin Marcelo
(74) Attorney, Agent, or Firm—Sughrue Mion, PLLC
In order to restore a network after a failure, it is important to have sufficient spare capacity available. To ensure restorability, a Hamiltonian mesh, being a closed sequence of links traversing each network node exactly once, is determined and half of its capacity is reserved for restoration purpose. In the case of a line failure of a link other than the links of the Hamiltonian mesh, affected traffic is split in two portions and rerouted over the two directions of the Hamiltonian mesh. In the case the network has no Hamiltonian mesh, a mesh coverage is determined and sufficient spare capacity reserved for restoration purpose.
19 Claims, 8 Drawing Sheets