Limited multicast communication method and communication network system realizing the method

Claim 1

A communication network system to which a plurality of stations are connected through a communication network, in which an identical message is transmitted to a plurality of arbitrarily designated stations, comprising: comparison means (26) for holding input reference data, for checking, based on the held reference data, if a transmitted message is destined to be sent to an intrastation, and for generating an input instruction when it is determined that the transmitted message is destined to be sent to the intrastation; data input/output means (22, 24, 30, 32) for storing a message, and for transmitting the stored message in response to an output instruction input thereto, in the case of transmission; and for outputting the destination address in the transmitted message to said comparison means (26), and for receiving the transmitted message in response to the input instruction input from said comparison means (26), in the case of reception; and control means (28) for outputing an intra-address to said comparison means (26) as the reference data, and for writing a message to be transmitted in said data input/output means (22, 24, 30, 32) in accordance with one of completion of receiving the message and a transmission instruction, input thereto, indicating multicast communication or individual communication, and outputting the output instruction to said data input/output means (22, 24, 30, 32) when the message is completed, in the case of transmission; and for checking the received message in the case of reception, characterized in that said control means (28) further comprises: notice transmission means (28) for writing a notice message including an identifier in said data input/output means (22, 24, 30, 32) in accordance with the transmission instruction when it is determined that the input transmission instruction designates limited multicast communication; notice receiving means (28) for outputting the identifier in the received notice message to said comparison means (25) as the reference data; and limited multicast message transmission means (28) for writing a limited multicast communication message having the identifier in said data input/output means (22, 24, 30, 32) in accordance with the transmission instruction, and characterized in that said comparison means (25) checks based on the identifier as the reference data if the limited multicast communication message transmitted is destined to be sent to the intrastation.

Claim 3

The system according to claim l, characterized in that said notice transmission means (28) includes means (28) for writting the notice message including as the identifier a text identifier for defining a text in said data input/output means (22, 24, 30, 32), said notice receiving means (28) includes means (28) for outputting the text identifier written in the received notice message as the reference data, to said comparison means (28), and said limited multicast message transmission means (28) includes means (28) for writing the limited multicast communication message including the text identifier in said data output/input means (22, 24, 30, 32).

Claim 6

The system according to claim l, characterized in that said comparison means (25) further comprises means (27) for receiving a source address as additional reference data from said data input/output means (22, 24, 30, 32), and for checking, based on the additional reference data input and held therein, if the trans­mitted message is a message destined to be sent to the intrastation, said notice transmission means (28) includes means (28) for writting the notice message further comprises a command indicating the limited multicast communication in said data input/output means (22, 24, 30, 32), said notice receiving means (28) further comprises means (28) for outputting an address of a source station written in the received notice message to said com­parison means (25) as the additional reference data when it is determined that the command in the received notice message designates the limited multicast communicaton, and said limited multicast message transmission means (28) includes means (28) for writting the limited multicast communication message including a limited multicast address as the destrination address and the intra-address as the source address in said data input/output means (22, 24, 30, 32).

Claim 13

The method according to claim l0, character­ized in that the prior notice is transmitted using a frame including an address of one of said plurality of arbitrarily designated stations as a destination address, the address of the source station as a source address, and a command indicating that the message is the prior notice, and said receiving of the prior notice includes discriminating from the destination address that the message is destined o be sent to the intrastation, to hold the source address as the identifier in the prior notice.

Claim 15

The method according to claim l2, characterized in that the prior notice is multicast-transmitted using a frame including a multicast address indicating multicast transmission, a command indicating that the message is the prior notice, and a string of addresses of the plurality of arbitrarily designated stations, and said receiving of the prior notice includes discriminating from the multicast address that the message is destined to be sent to the intrastation, to hold the source address in the prior notice when the intra-address is detected in the string of addresses.

Claim 16

The method according to one of claims 9 through l3, characterized in that said transmitting of the identical text message includes transmitting the identical text message including the address of the source station defined in the prior notice and a limited multicast address for indicating limited multicast transmission, from the source station, and said receiving of the identical text message includes discriminating that the text message is a limited multicast message from the limited multicast address, and that the text message is destined to be sent to the instrastation, comparing the address of the source station in the text message with the held address as the identifier, to receive the text in the text message.

Claim 18

The method according to claim l5, characterized in that said transmitting of the prior notice includes sequentially and individually transmitting to the prior notice the plurality of arbitrarily designated stations.

Claim 19

The method according to claim l5, characterized in that the prior notice is transmitted using a frame including an address of a destination station, a command indicating the prior notice, and the text identifier, and said receiving of the prior notice includes discriminating from the address of the destination address that the transmitted message is the prior notice, to hold the text identifier in the prior notice.

Claim 20

The method according to claim l5, characterized in that said transmitting of the prior notice includes multicast-transmitting the prior notice to the plurality of arbitrarily designated stations

Claim 21

The method according to claim l5, characterized in that the prior notice is multicast-transmitted using a frame including multicast address, the text identifier, and a string of addresses of the plurality of arbitrarily designated stations, and said receiving of the prior notice includes discriminating from the multicast address that the prior notice is to be sent to the intrastation, to hold the text identifier when the intra-address is detected in the string of addresses.

Claim 22

The method according to one of claims l5 through l9, characterized in that said transmitting of the identical text message includes multicast-transmitting the identical text message including the text identifier, and said receiving of the identical text message includes discriminating that the identical text message is destined to be sent to the intrastation, comparing the received text identifier with the held text identifier, to receive the text in the text message.