Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-02-27
2001-08-07
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S432000, C370S475000
Reexamination Certificate
active
06272135
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data communication method used for executing data exchange between different networks by connecting a plurality of networks via relay units including gate ways, root hubs, or hubs mutually, and a data communication system using this communication method. More particularly, the present invention relates to a data communication method capable of surely transmitting communication data to a designated node terminal as a destination without a reduction in data transmission capacity per unit time, even when data exchange is executed between the different networks with the intervention of one or more than two networks in communication routes and also data communication routes branch out into plural routes with the travel of communication data, and a data communication system using this communication method.
2. Description of the Prior Art
In the prior art, as disclosed in Patent Application Publication (KOKAI) 59-62245, for example, a data communication system has been widely known in which a plurality of local area networks (referred to as “LAN's” hereinafter) used to execute data exchange between a plurality of stations are connected via gate ways to enable data exchange between LANs.
According to the technology disclosed in the above Publication, in addition to a transmitter/receiver address for designating the transmitter and the receiver of data respectively, both a transmitting or receiving station address indicating the data transmitting or receiving station and a network address indicating the network to which the data transmitting or receiving station belongs have been provided in the transmitter/receiver address of the communication data. Hence, even if data communication is to be carried out beyond its own network, certain data communication between different LAN's has been made possible by referring to these addresses upon data communication.
However, according to the addressing approach used in the above data communication system in the prior art, the network address designated as the destination and the network address peculiar to the LAN in which the communication data reside are compared with each other and then it is determined timely whether or not the communication data reach the destination LAN based on the result that these addresses coincide with each other or not. For this reason, at the time when the data communication is enabled between LAN's with the intervention of one or more than two LAN's in the communication routes, for example, if data communication routes branch out into plural routes with the travel of communication data, it has not been able to be decided which branch route the communication data is to be supplied to, so that the communication data have reached the destination LAN while making a detour on the route. As a result, in the above data communication system in the prior art, such a problem to be overcome has resided that it is difficult to increase data transmission capacity per unit time.
Moreover, according to the addressing approach in the above data communication system in the prior art, such another problem to be overcome has arisen that it is difficult to satisfy the request that the communication data should be broadcasted from one source to plural destinations.
SUMMARY OF THE INVENTION
The present invention has been made in light of the above circumstances, and it is an object of the present invention to provide a data communication method which is able to transmit communication data surely to a designated one or more than two node terminals as destinations without a reduction in data transmission capacity per unit time, even when data exchange is executed between a plurality of networks with the intervention of one or more than two networks in communication routes and also data communication routes branch out into plural routes with the travel of communication data, by providing an addressing area in a data area of the communication data serving as a transmission object and then, if one-to-one communication is carried out between the node terminals, writing previously in this addressing area root addresses which are constructed by arranging their own addresses of relay units positioned at branch points in the communication routes in their passing order or, if one-to-plural broadcast communication is carried out between the node terminals, writing previously broadcast group addresses of node terminal groups as broadcast destinations in place of the root addresses in this addressing area, and a data communication system using this communication method.
In order to achieve the above object of the present invention, according to an aspect of the present invention, there is provided a data communication method used to execute data exchange between a plurality of networks which are connected via relay units mutually and to which node terminals are connected respectively, comprising the steps of: writing previously root addresses, which are constructed by aligning in passing order addresses of the relay units existing at branch points in communication routes, into an addressing area of a data area of communication data serving as a transmission object if one-to-one communication between node terminals is to be executed; otherwise, writing previously broadcast group addresses of node terminal groups as broadcast destinations in place of the root addresses into the addressing area of the data area of communication data serving as the transmission object if one-to-plural broadcast communication between node terminals is to be executed; decoding the root addresses or the broadcast group addresses included in the communication data transmitted from the node terminals by the relay units; deciding that the communication data are transmitted via either one-to-one communication between node terminals or one-to-plural broadcast communication between node terminals, by the relay units based on the decoded root addresses or the decoded broadcast group addresses; when, as a result of the above deciding step, it is decided that one-to-one communication between node terminals is executed, comparing/deciding by the relay units whether or not previously stored addresses of the relay units are included in the decoded root addresses, then selecting appropriate routes as a destination of the communication data by the relay units based on a result of comparison/decision, and then transmitting the communication data to node terminals designated as the destination via the selected routes; and when, as the result of the above deciding step, it is decided that one-to-plural broadcast communication between the node terminals is executed, selecting appropriate routes as the destination of the communication data by the relay units based on the decoded broadcast group addresses and addresses peculiar to the node terminals belonging to node terminal groups corresponding to the broadcast group addresses stored previously, and then broadcasting the communication data to a plurality of node terminals designated as the broadcast destinations via the selected routes by the relay units.
According to the present invention, the relay units can decode the root addresses or the broadcast group addresses included in the communication data transmitted from the node terminals, and then decide that the communication data are transmitted via either one-to-one communication between node terminals or one-to-plural broadcast communication between node terminals based on the decoded root addresses or the decoded broadcast group addresses. When it is decided as a result of the above decision that one-to-one communication between node terminals is executed, the relay units can compare/decide whether or not previously stored own address is included in the decoded root addresses, then select appropriate routes as a destination of the communication data based on a result of comparison/decision, and then transmit the communication data to node terminals designated as the destination
Chin Wellington
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pham Brenda H.
Yazaki -Corporation
LandOfFree
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