Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1997-08-28
2001-07-10
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S537000, C370S542000
Reexamination Certificate
active
06259693
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
Network switches provide signal connections between a plurality of input ports and a plurality of output ports. Each network switch typically comprises at least one switch fabric for facilitating these signal connections. The signal connections are made between the switch fabric and the input ports and the output ports.
Each switch fabric is typically located on its own printed circuit board within the network switch. Likewise, any circuitry that is associated with the input ports and the output ports is typically located on separate printed circuit boards within the network switch. A motherboard or backplane is provided in order for the signal connections to be made between the switch fabric and the input ports and the output ports. That is, the backplane provides physical connections between the switch fabric and the input ports and the output ports. It is over these physical connections that the signal connections are made.
Depending on the size of the network switch, it may be required that a large number of signal connections must be made between the switch fabric and the input ports and the output ports, and, correspondingly, a large number of physical connections must be made across the backplane between the switch fabric printed circuit board and the printed circuit board(s) associated with the input ports and the output ports. There are problems associated with such a large number of physical connections being made across a backplane, including printed circuit board area limitations and signal noise interference. Accordingly, it would be beneficial to reduce the number of physical connections that must be made across the backplane between the switch fabric printed circuit board and the printed circuit board(s) associated with the input ports and the output ports, while not reducing the data rate associated with the signal connections.
In addition to the benefit of reducing the number of physical connections between the switch fabric printed circuit board and the printed circuit board(s) associated with the input ports and the output ports, it would also be beneficial to utilize the reduced number of physical connections in a most efficient manner. That is, it would be beneficial to utilize the reduced number of physical connections between the switch fabric printed circuit board and the printed circuit board(s) associated with the input ports and the output ports in an efficient manner so that signal connections may be made to provide for signal redundancy and to compensate for hardware failures. Accordingly, it would be desirable to provide an apparatus and method for efficiently transferring data across a backplane in a network switch.
Some switch devices have plural elements which require access to a switch fabric, yet these elements collectively require an amount of bandwidth which does not exceed the bandwidth provided by a single thread through the switch fabric. Therefore, it would be beneficial to be able to make such network elements share the single thread, while ensuring that their collective bandwidth does not exceed the available thread bandwidth.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus and method for efficiently transferring asynchronous transfer mode (ATM) cells across a backplane in a network switch. The present invention is realized through an electrical apparatus that converts parallel data that is received on parallel data input ports to serial data that is transmitted on serial data output ports. The parallel data that is received on each parallel data input port is divided and transmitted from a corresponding pair of serial data output ports. The electrical apparatus also converts serial data that is received on serial data input ports to parallel data that is transmitted on parallel data output ports. The serial data that is received on a corresponding pair of serial data input ports is combined and transmitted from a parallel data output port.
In addition to converting parallel input data to serial output data and converting serial input data to parallel output data, the electrical apparatus can direct converted parallel input data from any of the parallel data input ports to any of the corresponding pairs of serial data output ports and can direct converted serial input data from any of the corresponding pairs of serial data input ports to any of the parallel data output ports.
The electrical apparatus can also direct converted parallel input data from any of the parallel data input ports to more than one of the corresponding pairs of serial data output ports. The electrical apparatus can also direct converted serial input data from any of the corresponding pairs of serial data input ports to more than one parallel data output ports.
The electrical apparatus can further direct converted serial input data from more than one of the corresponding pairs of serial data input ports to a single parallel data output port. The electrical apparatus can also direct converted parallel input data from a single parallel data input port to either of one or another of the corresponding pairs of serial data output ports according to the value of a switching bit in a cell header of the converted parallel input data.
The above-described functions of the electrical apparatus allow the number of physical connections that must be made across a backplane in a network switch to be reduced, while not reducing the data rate associated with signal connections utilizing those physical connections. Furthermore, the above-described functions of the electrical apparatus allow the reduced number of physical connections to be used in an efficient manner so that signal connections may be made to provide for signal redundancy and to compensate for hardware failures in the network switch.
By enabling plural serial input ports to access a single parallel output port, plural network switch elements can share a single thread through a switch fabric. In particular, the present invention finds use in interleaving the relatively low bandwidth cell outputs of two central control processors onto a single thread. This thread is routed through an interconnected switch fabric. Certain of these cells originated by a first of the central control processors, destined for a second of the central control processors, are routed through the switch fabric as part of the interleaved cells and are subsequently separated from other cells, according to one or more bits set in a header portion of each cell, enabling routing to the second central control processor.
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Baracka, Jr. Ronald Louis
DeAngelis Patrick L.
Ganmukhi Mahesh N.
Ascend Communications, Inc.
Chin Wellington
Tran Maikhanh
Weingarten, Schurgin Gagnebin & Hayes LLP
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