Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
1998-12-31
2003-07-29
Kizou, Hassan (Department: 2662)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
C370S235000, C370S349000, C709S203000
Reexamination Certificate
active
06600721
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to transferring information through a network. More particularly, the present invention relates to pacing information between end nodes and a network.
2. Description of Related Art
Modern network devices transfer information using a protocol such as an ethernet or an asynchronous transfer mode (ATM) protocol. A network transfers information from a first end or source of information, e.g. a server or an end node, to a second end or destination e.g.la second server or second end node. In recent years, it has become common to use giga-switches to couple large numbers of end nodes to a bank of servers. Many of these end nodes are coupled to the giga-switch through multiplexers.
Using multiplexers to couple end nodes to a giga-switch results in significant fluctuations in the quantity of data transferred between the switch and the end node. For example, when multiple workstations serving as end nodes simultaneously uplink information, the uplink may be overloaded. Thus, large buffers are used to store data that may be suddenly uploaded to avoid overloading the uplink.
At an opposite end, information is downloaded from the switch to the end node. The data flow from the switch through the multiplexer to the end node may be significantly higher than the end node can handle at a particular point in time. Thus, the network also includes a buffer to buffer received packets of data for transfer to the end node.
One method of “throttling data” or controlling data flow to the client device uses in-band flow control. Flow control uses the transmission of flow control, data “on” and data “off” signals to switch off data flow from a source device. The transmission of on and off signals to a receiving device such as an end node, requires additional control circuitry, and is inefficient because it uses buffers to temporarily store data in the network while the off signal stops the flow of data until data within the buffer is consumed.
The large buffers used to cache data flow between transmission of flow control signals uses significant hardware resources and increases the complexity and expense of the network system. Thus, a method of transferring data through a network using smaller buffers is desirable.
SUMMARY OF THE INVENTION
A method and apparatus for pacing packets of data for transfer through a network is described. Prior to transmitting the data, a bandwidth is negotiated between an end node and the network or a policy manager. The negotiated bandwidth determines the transmission rate of packets between the switch and the end node. Packet transmissions are scheduled according to the negotiated transmission rate. In one embodiment of the invention, the system adjusts the latency between packets to conform to the negotiated bandwidth.
REFERENCES:
patent: 5936940 (1999-08-01), Marin et al.
patent: 5995488 (1999-11-01), Kalkunte et al.
patent: 6105064 (2000-08-01), Davis et al.
patent: 6118787 (2000-09-01), Kalkunte et al.
patent: 6173325 (2001-01-01), Kukreja
Blakely , Sokoloff, Taylor & Zafman LLP
Elallam Ahmed
Kizou Hassan
Nortel Networks Limited
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