Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing
Reexamination Certificate
1997-08-05
2001-02-13
Maung, Zarni (Department: 2757)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
C710S038000, C710S014000, C710S120000
Reexamination Certificate
active
06189040
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to data relaying units which are suitable for use with serial buses and also relates to methods of transmitting data between host and client devices.
In the following description, the term “bus” refers to a data transmission path to which a plurality of devices are connected and whose input/output schedule is managed by a host computer.
With development in information-oriented society today, personal computers have been rapidly coming into wide use in various fields, and in some business organizations, almost every employee has a personal computer on his or her desk. Also, for the purpose of conducting particular operations using a plurality of personal computers, a LAN (Local Area Network) system may be built to share same information and pieces of peripheral equipment such as a printer and a facsimile.
FIG. 11
shows a typical example of a LAN system arranged with star-connecetd token buses, where reference numeral
1
represents a host device or host computer in the form of a personal computer and reference character H represents a hub device connected to the host device to function as a concentrator device for the data buses. Further, reference characters A, B and C represent client devices connected with the hub device H, each of which comprises a personal computer or peripheral equipment. Among these devices, data divided into a plurality of predetermined time units called “time slots” are transmitted via serial buses composed of twisted pair lines. Via the hub device H, the host device
1
controls data transmission between the client devices A-C and between the host device
1
and each of the client devices A-C. That is, the host device
1
control distribution of data flowing through the data buses, and such control is generally known as “bus scheduling”.
However, the rates of the data transmissions between the devices are subject to a certain limit depending on the respective performance of interfaces used. Thus, if a large quantity of data are to be transmitted between specific client devices in a time slot, there would arise a problem that the data transmission between other client devices than the above-mentioned specific client devices is limited to a considerable degree. Assuming that a large quantity of data are to be transmitted from the client device A to the client device B in a specific time slot, the host device
1
performs the bus scheduling as shown in FIG.
12
. Most part of this specific time slot is occupied by the data transmission period T
1
from the client device A to the client device B and the data transmission between the host device
1
and the other client device C is significantly limited because it can be conducted only at the remaining time T
2
of the time slot.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a data relaying unit which permits an efficient data transmission.
In order to accomplish the above-mentioned object, a data relaying unit in accordance with the present invention includes a quasi host device to control direct data transmission between a plurality of client devices. The data relaying unit also includes a connection switching device which performs connection switching such that when data are to be transmitted between the client devices, it connects data input/output terminals, corresponding to the client devices, to the quasi host device, but when data are to be transmitted between the host device and one of the client devices, it connects the input/output terminals to input/output terminals of the host device.
In a preferred implementation, the data relaying unit in accordance with the present invention is provided for connection between a host device and a plurality of client devices and comprises: a plurality of connectors corresponding to the client devices; a control device which, when the host device instructs that data transmission should be performed between specific ones of the client devices, manages a schedule for the data transmission between the specific client devices; and a connection switching device which connects the connectors corresponding to the specific client devices to the control device and connects the other connector corresponding to the other client device to the host device. Thus, data are transmitted between the specific client devices in accordance with the schedule managed by the control device, without intervention of the host device.
Here, the above-mentioned control device corresponds to the quasi host device. When data are to be transmitted between the client devices, the host device only instructs the data relaying unit from which of the client devices data should be transmitted and by which of the other client devices these data should be received. Actual processing necessary for the data transmission is carried out in accordance with the control device of the data relaying unit, i.e., the quasi host device, in a direct manner without intervention of the host device. This arrangement can effectively shorten a time in which the host device has to be bound by the processing for the data transmission process between the client devices. The quasi host may monitor a condition of the data transmission between the client devices and inform the host device of presence/absence of any unusual condition or the like.
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patent: 5764895 (1998-06-01), Chung
patent: 5784581 (1998-07-01), Hannah
patent: 5787256 (1998-07-01), Marik et al.
patent: 5832492 (1998-11-01), Wooten
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Maung Zarni
Morrison & Foerster
Salad Abdullahi E.
Yahama Corporation
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