Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1997-12-08
2001-05-01
Chin, Wellington (Department: 2664)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S398000
Reexamination Certificate
active
06226263
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to asynchronous transfer mode (ATM) networks, and more specifically to the reservation of network resources in an ATM network in response to users' requests.
2. Description of the Related Art
Japanese Laid-Open Patent Specification Hei-6-30021 discloses time-scheduled communications in a switched network in which ATM switching nodes individually perform reservation of a bandwidth according to user's reservation requests by storing reservation requests in memory and monitoring the stored requests in order to establish a connection at requested time of day if network resource is available. After the connection is established, the ATM switches monitor the stored request in order to release it at the expiry of the reservation.
Since the prior art resource reservation is implemented individually on a per-node basis and no facility is available to link the reservation data between ATM switches, network reservation cannot be performed on an end-to-end basis. In addition, network resource reservation is attempted at the very instant at which the scheduled communication begins. Although the prior art is provided with means for rejecting some calls if they occur during a predetermined interval prior to the scheduled communication, there is some degree of uncertainty to satisfy the reservation request at the beginning of the scheduled communication. Furthermore, if the ATM switches fail to satisfy a reservation request at the beginning of the scheduled communication, there is no fallback procedure for continuing the search for the requested network resource.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a solution to the problems associated with ATM switches for making a reservation of network resource.
According to a first aspect of the present invention, there is provided a network controller for making a resource reservation in a network formed by a plurality of ATM switches interconnected by communication links. The network controller comprises a data base for holding data pertaining to network topology and remaining network resource, a supervisory circuit for constantly monitoring the communication links, a registration memory, and route decision and resource reservation logic circuitry. The logic circuitry updates the data base if a faulty condition is detected by the supervisory circuit and receives, from a source terminal, a reservation request indicating a reservation of an end-to-end network resource between a scheduled start time and a scheduled end time, making a search through the data base to reserve the network resource in the data base if the network resource is available. The logic circuit causes the ATM switches to establish an end-to-end connection using the reserved network resource at the scheduled start time, informs the source terminal of a virtual channel identifier/virtual path identifier of the established connection to be used for subsequent transmission of messages, releases the established connection when the request stored in the registration memory indicates the scheduled end time and removes the request from the registration memory.
According to a second aspect of the present invention, the reservation request further indicates one of first and second reservation classes, and the logic circuitry is arranged to make a search through the data base, if the request is indicating the first class, to determine whether the network resource is available immediately following the receipt of the request, reserve the network resource and cause the ATM switches to establish the connection using the reserved network resource at the scheduled start time if the network resource is available, and is further arranged to make a search through the data base, if the request is indicating the second class, to determine whether the network resource is available at the scheduled start time, and cause the ATM switches to establish the connection using the network resource if the network resource is available.
According to a third aspect of the present invention, the logic circuitry is arranged to store the request in a waiting memory if the network resource is determined to be unavailable, make a search through the data base to determine, when an existing connection is released, whether the network resource is available, and cause the ATM switches to establish the connection using the network resource and remove the request from the waiting memory if the network resource is available.
REFERENCES:
patent: 5267232 (1993-11-01), Katsube et al.
patent: 5479402 (1995-12-01), Hata et al.
patent: 5687167 (1997-11-01), Bertin et al.
patent: 5745694 (1998-04-01), Egawa et al.
patent: 5784358 (1998-07-01), Smith et al.
patent: 5970062 (1999-10-01), Bauchot
patent: 6041038 (2000-03-01), Aimoto
patent: 0629065 (1994-12-01), None
patent: 6-30021 (1994-02-01), None
European Search Report (in English) issued Jan. 24, 2000 in a related application.
Iwase Toshio
Nakashima Shinichi
Nose Masayoshi
Tsuchida Hisazumi
Chin Wellington
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Yao Kwang B.
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