Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-02-06
2001-08-21
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
Reexamination Certificate
active
06278714
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to communication systems and, more particularly to the creation, maintenance, use and deletion of virtual channels in a network environment.
2. Description of Related Art
Modern data networks trace their historical origins to telephone switching networks. Telephone switching networks set up connections between an originating caller and a called subscriber selected by dialing the called subscriber's telephone number.
Digital networks are known which permit information packets to be routed from a source to a destination without the necessity for a hardwired connection between the calling subscriber and the destination subscriber. Packets are routed over links between nodes of a network. Rather than a physical connection, a virtual connection, sometimes called a virtual channel or virtual circuit is defined between the source of the packet and its destination. A virtual circuit gives the appearance of maintaining a hardwire connection, but utilizes the resources of the connection only when data need to be sent. This permits the link to be shared by other virtual circuits and improves the efficiency and throughput of the links of the network.
One form of modern high speed network uses a set of standards collectively termed asynchronous transfer mode (ATM). The basic data element used by these networks is a cell, which is a sequence of 53 bytes of which the first 5 are the header and the other 48 are the cell payload. To allow very high data rates (in the hundreds of megabytes per second and above) the switching time of a cell in every switch or node along the route through the network must be minimal. ATM networks achieve this by way of a virtual channel mechanism which requires a set-up phase before the actual data stream can be transported from source to destination. The notion of a virtual path is defined in the ATM standard. Each virtual path “contains” 2
16
(65,536) virtual circuits. Supporting virtual path requires significant additions to the ATM switch hardware. Consequently, many switches only support virtual circuits; they do not support virtual paths.
The Problems
It would be desirable to have an efficient mechanism for quickly allocating multiple connections. Further, it would be desirable to reduce the table size required for network switches to support large numbers of virtual circuits. It would further be desirable to implement multiple virtual channels set-up while maintaining compatibility with current switches but nevertheless supporting heterogeneity in switches in a network. It would further be desirable to be able to route multiple virtual circuits over different paths. It would also be desirable to support dynamic aggregation of individual virtual circuits into larger entities. It would also be desired to permit enhanced resource sharing across connections of a network. It would further be desirable to have techniques for handling ATM cell interleaving problems in a multi-sender multi-cast. It would also be desirable to have efficient support for fast connection establishment. It would further be desirable to improve the efficiency with which “keep-alive” and “refresh” packets are sent through the network.
SUMMARY OF THE INVENTION
The problems of the prior art are solved in accordance with the invention by providing a new entity for use in networks called the Virtual Circuit Bunch (VCB). Virtual Circuit Bunches can be utilized to set-up and manage together groups of virtual circuits in a flexible way which results in increased performance as well as overcoming the problems of the prior art.
The Virtual Circuit Bunch, as set forth herein, enables groups of Virtual Circuits to be established between one or more points of origin and one or more destinations. In one form Virtual Circuit Bunches can be implemented without any changes to switch hardware and permit great flexibility in Virtual Circuit allocation. In another form, changes resulting in an improved Forwarding and Translation Table result in improved management of Virtual Circuit Bunches by permitting a VCB to be managed with a single table entry. This form is preferably implemented in hardware.
One aspect of the invention is directed to a switching node which includes a switching matrix, and a controller to control the switching matrix, in which the controller is configured to set up an entry group of virtual circuits as a virtual circuit bunch, using a single table entry.
Another aspect of the invention is directed to a method of allocating virtual circuits, by establishing a plurality of virtual circuits from one node to at least one other node as a virtual circuit bunch in response to a single request.
Another aspect of the invention relates to a method of identifying virtual circuits at a node going to a common destination node; and aggregating those virtual circuits into a virtual circuit bunch.
Another aspect of the invention relates to a method of providing a fast connect service in a digital switching network by appropriately assigning a packet to a virtual circuit of a virtual circuit bunch without establishing a connection.
Another aspect of the invention relates to a method of allocating virtual circuits in a switching system allocating a virtual circuit to all nodes participating in a multicast using a virtual circuit bunch.
Another aspect of the invention relates to a system for the transmission of digital communications, including a plurality of user communication devices; a plurality of at least partially interconnected switching nodes, each node serviced by a node controller servicing said user communications devices; in which at least one of said node controllers is configured to set up a group of virtual circuits to respective one or more destinations as a virtual circuit bunch.
Other aspects of the invention are directed to computer program products for carrying out the invention.
The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5530806 (1996-06-01), Condon et al.
patent: 5627836 (1997-05-01), Conoscenti et al.
patent: 5872783 (1999-02-01), Chin
patent: 5936959 (1999-08-01), Joffe
patent: 5951649 (1999-09-01), Dobbins et al.
patent: 6069895 (2000-05-01), Ayandeh
Chin Wellington
Jones Prenell
McDermott & Will & Emery
Sun Microsystems Inc.
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