Electrical computers and digital processing systems: multicomput – Bused computer networking
Patent
1998-06-15
2000-08-08
Harrell, Robert B.
Electrical computers and digital processing systems: multicomput
Bused computer networking
G06F 1300
Patent
active
061015547
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to apparatus for monitoring and controlling data flow in a computer network device.
BACKGROUND OF THE INVENTION
Computer networks are well known and basically there are two popular types i.e. a token ring network and an ethernet network. Such networks are now well defined. In other words, in order to have compatible equipment and software certain features have to be present in order to comply with the standard.
It is known to divide up a large network using devices called bridges and in ethernet technology a bridge is a defined device having defined characteristics. However, we have in the past modified such devices as that they retain i he defined operations of a bridge but also, within the device, handle data in a different manner so as to economize on memory. In our terminology a modified bridge is termed a switch.
In modern networks, more and more control of data flowing in the network is required in order to avoid bottle-necks which cause delays. There is thus a need for a high performance low cost switch or bridge.
SUMMARY OF THE INVENTION
The present invention proposes apparatus for monitoring and controlling data flow in a computer network device having a plurality of ports, the apparatus including control means for directly linking ports together on the basis of additional information stored in the control means whereby incoming packets are linked directly to an output port to achieve high performance.
Preferably, the additional information is stored in look-up table means additional to the normal CAM or equivalent mechanism- The look-up table means could be in the form of one large table or a plurality of smaller tables. Each table is addressed using separate processing.
This arrangement with its system of tables is ideal for implementation in hardware (e.g. in silicon), rather than in software, thus allowing for low cost implementation.
In order that the present invention be more readily understood an embodiment thereof will now be described by way of example with reference to accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a diagrammatic lay out of the structure of a device according to the present invention,
FIG. 2 shows a representation of one part of a device as shown in FIG. 1; and
FIG. 3 shows diagrammatically a typical burst of data for transmission between ports in the device shown in FIG. 1.
DETAIL DESCRIPTION
The preferred embodiment of the present invention is shown in FIG. 1 and will be seen to comprise a multi-port switch having ports 0 to n to which devices such as computer terminals, servers, printers and modems may be attached.
Within the switch there is a data bus and a control bus although for convenience, only a single bus is indicated in the drawing. Each port is connected to the data and control buses it is common to select one particular port to connect to rest of network. This port is known as the downlink port.
As will be seen from FIG. 1, each port is provided with transmit and receive buffers 4 in the form of memory devices.
Traffic through the switch is controlled by a control device generally indicate d by the reference numeral 10 which will be described in detail later. The control device is connected to the data and control buses and also communicates with a switch management entity in the form of a processor 11 and memory 12.
The control device 10 will now be described in more detail. It consists of look-up tables which are written into and read from under the control of three separate processing elements. One of the look-up tables is basically a modified content addressable memory (CAM) 15 or equivalent mechanism for storing MAC addresses and associated port numbers in a conventional manner. The CAM is used to store information associated with each MAC address, such as port number, age, types etc. Operation of the control device 10 is based upon a link table 16 which contains information relating to each of the ports of the switch and this table 16 is shown in more de
REFERENCES:
patent: 5140585 (1992-08-01), Tomikawa
Creedon Tadhg
Gahan Richard
Gavin Vincent
Hickey John
O'Connell Anne
3Com Ireland
Davis Paul
Harrell Robert B.
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