Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1997-07-21
2001-10-16
Patel, Ajit (Department: 2661)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S395430
Reexamination Certificate
active
06304577
ABSTRACT:
BACKGROUND ART
The present invention relates to network systems. More specifically, the invention relates to a node apparatus having an interface with a virtual-connection-oriented network and a method for managing a virtual connection to transmit packets from the node apparatus.
To transfer packets through a virtual connection in a virtual-connection-oriented network, such as an ATM (Asynchronous Transfer Mode) network, a virtual connection is set up one of two ways:
1) all virtual connections between nodes in the network are set up in advance of using the virtual connections to transfer packets (e.g., PVC (Permanent Virtual Connection) or VP (Virtual Path) in the ATM network); or
2) an adequate virtual connection is set up when it is required in order to transfer packets, and it is released when the transfer of packets terminates (e.g., SVC (Switched Virtual Connection) in the ATM network).
The first method makes it possible to use a virtual connection without waiting for setup when a node is starting to transmit a packet. However, a prior setup of all virtual connections by a human network manager has great difficulties. In addition, in the PVC method, it is difficult to determine how many virtual connections to preset. In the VP method, the usage of virtual connections may be inefficient because many virtual connections of the fixed number (e.g., 2
16
) are necessarily set up between all neighboring nodes.
The second method sets up a virtual connection from a first node to a second node by, for example, ATM signaling when the first node is transmitting a packet to the second node, and releases the virtual connection by ATM signaling when the first node finishes transmitting packets to the second node. Because the setup of a virtual connection starts after the virtual connection becomes necessary, a delay due to the setup exists until the node becomes able to transmit the packet. Moreover, the frequency of setup/release of virtual connections is high because the virtual connection is released each time it becomes unnecessary. This require the highest performance nodes and switches in the network for in setup/release signaling.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide a mechanism for obtaining a virtual connection with a smaller delay and with fewer setup/release actions using signaling.
A node consistent with this invention that is connected to a virtual-connection-oriented network comprises VC means for setting up and releasing virtual connections with a neighboring node; means for transmitting a packet to the neighboring node through an established virtual connection; and means for controlling the VC means to maintain at least one virtual connection with the neighboring node not currently in use by the means for transmitting.
A method consistent with this invention of managing a node connected to a virtual-connection-oriented network comprises the steps of setting up and releasing virtual connections with a neighboring node; transmitting a packet to the neighboring node through an established virtual connection; and maintaining at least one virtual connection with the neighboring node not currently in use by the means for transmitting.
Other features and advantage of the present invention will be become apparent from the following description taken in conjunction with the accompanying drawings. Both the foregoing general description and the following detailed description provide examples consistent with this invention and explain how to make and use systems and methods consistent with the invention. These description do not restrict the claimed invention.
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patent: 5452296 (1995-09-01), Shimuzu
patent: 5463621 (1995-10-01), Suzuki
patent: 5548589 (1996-08-01), Jeon et al.
patent: 5751698 (1998-05-01), Cushman et al.
patent: 0 603 915 A2 (1994-06-01), None
Katsube et al., “Internet Engineering Task Force,” Internet Draft, Mar. 25, 1996.
Shelef, “SVC Signaling: Calling All Nodes,” Data Communications, vol. No. 8, New York, Jun. 24, 1995; pp. 123-130.
Roux et al., “Broadband ISDN signalling techniques and benefits,” Communication & Transmission, Paris, France, 1995; pp. 59-70.
Katsube Yasuhiro
Nagami Kenichi
Tanaka Hisako
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Nguyen Brian
Patel Ajit
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