Multiplex communications – Fault recovery – Bypass an inoperative station
Reexamination Certificate
1997-07-15
2004-06-15
Vu, Huy D. (Department: 2667)
Multiplex communications
Fault recovery
Bypass an inoperative station
C370S390000
Reexamination Certificate
active
06751192
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a communication network in which node devices to each of which a plurality of terminals have been connected are connected by parallel multiplexed transmission lines, as well as to a method of controlling this communication network.
The need to handle greater quantities of information has made it necessary to increase the speed and capacity of networks which connect terminal equipment. To achieve this, network systems in which node devices are connected by parallel multiplexed transmission lines have been studied. Such node devices and a network system which uses them will now be described.
FIG. 1
is a diagram useful in describing the principle of communication of a network system of the kind mentioned above. The network system includes node devices
101
~
104
having exchange switches
105
~
108
and buffers
109
~
112
, respectively, terminals
121
~
136
, and parallel transmission lines A, B, C, D which construct a ring. The communication principle of the network system shown in
FIG. 1
will now be described.
The plurality of parallel transmission lines A, B, C, D of the network are interconnected by the exchange switches
105
~
108
. Each terminal is connected to one of the parallel transmission lines among the lines A, B, C, D. In a case where one terminal connected to one parallel transmission line communicates with a terminal connected to another parallel transmission line, communication is carried out by switching the first-mentioned terminal to the other parallel transmission line at least one time by any exchange switch. Though the position at which switching is performed is not specified, communication control is facilitated if it is so arranged that the changeover is made to the transmission line of the destination at the node immediately preceding the destination node, with the transfers to arbitrary transmission lines being made at other nodes. In order to simplify the node devices, the exchange switches
105
~
108
of the network change the input/output connection relationship at a fixed period in accordance with a specific cyclic pattern irrespective of the input signals. After the input signals have been stored temporarily in the buffers
109
~
112
, packets are read out of the buffers when the input/output connection relationship of the exchange switches has attained a desired relationship. This is the manner in which the network performs switching.
For example, in a case where a packet is transmitted from the terminal
122
, which is connected to the node device
101
, to the terminal
132
connected to the node device
103
, the packet output by the terminal
122
is stored in the buffer
109
of the node device
101
. When an input terminal IN
2
of the switch
105
is connected to, say, an output terminal OUT
2
, the packet is read out of the buffer and output to the transmission line B. The buffer enters the buffer
110
of the node device
105
. When the input terminal IN
2
and output terminal OUT
4
of the switch
106
are connected, the packet is read out of the buffer
110
, whereby the packet is output to the transmission line D and sent to the terminal
132
.
Thus, communication is carried out by transferring the packet to any parallel transmission line at each node device.
In a case where a broadcast is made from a certain transmitting terminal to all other terminals in the example of the prior art described above, connections must be established for all terminals. Since this increases the burden upon the transmitting terminal and network, the conventional system is impractical.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a network system and communication method in which the burden upon the transmitting terminal and network is reduced.
According to the present invention, the foregoing object is attained by providing a first network system for connecting a plurality of node devices by a plurality of parallel transmission channels and connecting terminals to respective ones of the plurality of transmission channels via the node devices, each of said node devices comprising:
memory section for temporarily storing transmission data by allotting the transmission data to a plurality of storage areas that correspond to respective ones of the plurality of transmission channels;
transmitting section for transmitting the data, which has been stored in said memory section, upon selecting any of the plurality of transmission channels; and
memory control section for controlling said memory section so as to read out the data that has been stored in the storage area that corresponds to the transmission channel that has been selected by said transmitting section;
said memory section having distributing section for distributing broadcast data, which is data, contained in the data that enters said memory section, that is to be transmitted over the plurality of transmission channels, to the plurality of storage areas that correspond to the plurality of transmission channels that are to transmit the data, thereby duplicating the broadcast data.
According to the present invention, the foregoing object is attained by providing a second network system for connecting a plurality of node devices by a plurality of parallel transmission channels and connecting terminals to respective ones of the plurality of transmission channels via the node devices, each of said node devices comprising:
memory section for temporarily storing transmission data, said memory section storing broadcast data, which is data, contained in the data that enters said memory section, that is to be transmitted over the plurality of transmission channels, upon distinguishing this broadcast data from data other than broadcast data;
transmitting section for transmitting the data, which has been stored in said memory section, upon selecting any of the plurality of transmission channels; and
memory control section for controlling said memory section so as to duplicate the broadcast data by reading out the broadcast data repeatedly whenever said transmitting section selects any of the plurality of transmission channels, and transmit the broadcast data by the plurality of transmission channels.
The characterizing features of the first and second network systems are the fact that the broadcast data is duplicated in a node device and the fact that control is performed in such a manner that the broadcast data is transmitted over all of the plurality of channels involved in transmission. As a result, the broadcast data can be transmitted in such a manner that the data can be received by a plurality of destinations without establishing a connection for each and every destination.
In order to connect the transmission channels and terminals, the connection is made via separating section in the node devices. The separating section preferably has a function for distributing data, which enters from a transmission channel, to the downstream side of the transmission channel and to the side on which the terminal is connected. In particular, if the separating section has selecting section for selecting, in dependence upon information described in the input data, whether the input data is to be output to the side on which the terminal is connected without being output to the downstream side of the transmission channel, or whether the input data is to be output to the downstream side of the transmission channel without being output to the side on which the terminal is connected, or whether the input data is to be distributed to the downstream side of the transmission channel and the side on which the terminal is connected, then, when it is indicated that the input data is broadcast data and, moreover, data that has already been duplicated by another node device, the data is distributed to the downstream side of the transmission channel and to the side on which the terminal is connected, whereby broadcasting can be realized without requiring that broadcast data that has been duplicated at any node be duplicated for a pluralit
Boakye Alexander O.
Vu Huy D.
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