Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1998-06-30
2001-06-26
Olms, Douglas (Department: 2732)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S417000
Reexamination Certificate
active
06252849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to information networks for computer systems and more specifically to systems for implementing flow control in an information network.
2. Description of the Related Art
Information networks transmit computer information such as computer data between various computer systems operably coupled to the information network. One type of information network is a local area network (LAN) utilizing a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) as specified by the IEEE standard 802.03, which is hereby incorporated by reference in its entirety. One problem with an information network is how to regulate the information being transmitted on the network such that the amount of information being transmitted does not overload the network. Another problem is how to fairly allocate the network resources among a multitude of users operably coupled to the system.
SUMMARY OF THE INVENTION
It has been discovered that allocating portions of an output buffer of an information network switch among input ports of the information network switch advantageously provides a flow control method that fairly allocates network resources among the information packet generators and sinks operably coupled to the network.
In one aspect of the invention, an information network switch includes a first input port for receiving information packets and a second input port for receiving information packets. The first input port has an enabled state and a disabled state, and the second input port has an enabled state and a disabled state. The information network switch also includes an output port for transmitting information packets. The output port includes a buffer for holding received information packets to be transmitted from the output port. A first portion of the buffer is allocated for holding information packets from the first input port and a second portion of the buffer is allocated for holding information packets from the second input port. The first input port transits to the disabled state from the enabled state in response to a level of occupancy of the first portion of the buffer exceeding a first level. The second input port transits to the disabled state from the enabled state in response to a level of occupancy of the second portion of the buffer exceeding a first level.
In another aspect, the invention includes a method of controlling the flow of information in an information network having an information network switch. The method includes allocating a first portion of a buffer of an output port of the information network switch for holding information packets received via a first input port of the information network switch and allocating a second portion of the buffer for holding information packets received via a second input port of the information network switch. The method also includes determining a level of occupancy of the first portion of the buffer and determining a level of occupancy of the second portion of the buffer. The method further includes providing a control signal to a first information packet source operably coupled to the first input port to inhibit the first information packet source from transmitting information packets to the first input port in response to the level of occupancy of the first portion of the buffer exceeding a first level. The method also includes providing a control signal to a second information packet source operably coupled to the second input port to inhibit the second information packet source from transmitting information packets to the second input port in response to the level of occupancy of the second portion of the buffer exceeding a first level.
In another aspect of the invention, an information network switch includes an output port for transmitting information packets to an information packet destination operably coupled to the output port. The output port includes a buffer for holding information packets to be transmitted to the information packet destination. The output port has a non hold state and a hold state. In the non hold state, the output port transmits information packets in the output buffer to the information packet destination. The output port transits to the hold state from the non hold state in response to the information network switch receiving a control signal provided by the information packet destination. In the hold state, the output port has a first sub-state and a second sub-state, in a first sub-state, the output port transmits information packets in the output buffer to the information packet destination. In the second sub-state, the output port does not transmit information packets to the information packet destination. The output port transits to the first sub-state from the second sub-state in response to the level of occupancy of the buffer exceeding a first level.
In another aspect of the invention, an information network switch includes a plurality of input ports for receiving information packets from information packet sources and a plurality of output ports for transmitting information packets received from the input ports to information packet destinations. Each output port includes a buffer for holding received information packets to be transmitted from the output port. The information network switch also includes means for implementing an allocated usage of each output port among the input ports.
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Khamisky Asad
Rom Raphael
Sidi Moshe
Dolezal David G.
Olms Douglas
Skjerven Morrill & MacPherson LLP
Sun Microsystems Inc.
Vanderpuye Ken
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