Telephonic communications – Plural exchange network or interconnection – Interexchange signalling
Reexamination Certificate
1997-06-20
2001-04-10
Matar, Ahmad (Department: 2642)
Telephonic communications
Plural exchange network or interconnection
Interexchange signalling
C379S026020, C379S221050
Reexamination Certificate
active
06215867
ABSTRACT:
TECHNICAL FIELD
This invention relates to a technique for providing an alternate signal path in a communications network upon failure of a network link.
BACKGROUND ART
Present day telecommunications carriers, such AT&T, carry large volumes of telecommunications traffic across their networks. While most carriers strive for high reliability, disruptions in their networks can and do occur. Such disruptions are often attributable to a failure in a link between two network nodes, each node typically comprising a telephone central office or network control center. The links, which may each take the form of a copper cable, optical fiber or a radio channel, may fail because of an act of nature, such as a flood, ice storm, hurricane or other weather-related occurrence. Link failures are sometimes man-made. Not infrequently, a contractor may accidentally sever a cable or fiber link during excavation along the link right-of way.
Regardless of the manner in which a communication link is severed, a link failure invariably disrupts communications services. For example, the loss of a single fiber in an optical cable usually results in many blocked calls. Each blocked call represents a loss of revenue for the carrier carrying that call. Thus, rapid restoration of traffic is critical. Typically, telecommunications carriers achieve traffic restoration by routing traffic on alternate routes. Since spare capacity often exists on many routes, traffic restoration is a matter of determining where such spare capacity exists and then establishing a path utilizing such spare capacity to bypass the severed link.
U.S. Pat. No. 5,182,744, “Telecommunications Network Restoration Architecture,” issued on Jan. 26, 1993, in the name of James Askew et al. and assigned to AT&T (incorporated by reference herein) discloses a restoration technique for routing telecommunications traffic on an alternate route in the event of a severed communications link. The Askew et al. technique utilizes communications monitors at the nodes to detect the disruption of traffic across the communications links. Should a disruption occur because of a failed link, the monitor at one or both of the affected nodes notifies a central facility that determines an alternate route over which the traffic can bypass the failed link. After finding a restoration route, the central facility directs the nodes to conduct a continuity test of the restoration route. Upon successful completion of the continuity test, the disrupted traffic passes over the restoration route.
While the Askew et al. restoration technique represents a significant advance over past approaches, the continuity test performed prior to restoration is not instantaneous. At present, restoration of one hundred DS3 signals takes about five minutes. Even though such an interval may seem insignificant, as many as 50,000 calls may be blocked during this time. Thus, there is a need for a technique achieves network restoration quickly, to reduce the incidence of blocked calls.
BRIEF SUMMARY OF THE INVENTION
Briefly, in accordance with a preferred embodiment of the invention, a technique is provided for restoring traffic within a telecommunications network upon the failure of a link coupling a pair of nodes. In accordance with the restoration technique of the invention, the links are monitored to determine a possible link failure. The failure of any link is reported to a central facility, typically, although not necessarily, by wireless communication. Upon receipt of a report of a failed link, the central facility determines a restoration route. In practice, the restoration route is determined in accordance with the location of the spare capacity within the network and on the traffic priority. The central facility the directs nodes, via an appropriate command, to establish the restoration route. At each node, each piece of traffic to be routed on the restoration route is uniquely identified. The unique identity of the each piece of traffic is utilized to determine the passage thereof on the restoration route to establish the continuity of the route without the need for any separate, time consuming continuity tests.
REFERENCES:
patent: 5058105 (1991-10-01), Mansour et al.
patent: 5146452 (1992-09-01), Pekarske
patent: 5182744 (1993-01-01), Askew et al.
patent: 5367562 (1994-11-01), Tourbah et al.
patent: 5420917 (1995-05-01), Guzman
patent: 5459716 (1995-10-01), Fahim et al.
patent: 5463615 (1995-10-01), Steinhorn
patent: 5465294 (1995-11-01), Chapman, Jr. et al.
patent: 5680326 (1997-10-01), Russ et al.
patent: 5832196 (1998-11-01), Croslin et al.
patent: 5848145 (1998-12-01), Gallagher et al.
patent: 5850505 (1998-12-01), Grover et al.
patent: 6018576 (2000-01-01), Croslin
FASTAR (sm)—A Robust System for Fast DS3 Restoration, C-W Chao, P.M. Dollard, J.E. Weythman, L.T. Nguyen, H. Eslambolchi, GLOBECOM '91, pp. 1396-1400, Dec. 1991.
FASTAR (sm) Operations in the Real AT&T Transport Network, H.S. Burns, C-W Chao, P.M. Dollard, R.E. Mallon, H. Eslambolchi, P.A. Wolfmeyer, GLOBECOM, pp. 229-233.
AT&T Corp.
Levy Robert B.
Matar Ahmad
Tieu Benny Q.
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