Network system

Abstract: A network system wherein any device in all networks can be represented using addresses set in the individual networks without relying upon the concept of a network number is disclosed. A first network (1) includes first to third devices (A, B, C) to which the addresses of "1", "2" and "3" are allocated, respectively. A second network (2) includes first to devices (D, E, F) to which the addresses of "1", "2" and "3" are allocated, respectively. A third network (3) includes first and second devices (G and H) to which the addresses "1" and "2" are allocated, respectively. The first and second networks (1, 2) are connected to each other by way of a gateway (GW1) and the second and third networks (2 and 3) are connected to each other by way of another gateway (GW2) to build up a network system. A pass from within a network to another device in another network is represented using the addresses set in the individual networks. For example, the pass from the first device (A) in the first network (1) to the second device (H) in the third network (3) is represented as "4.4.2".

Description: This invention relates to a network system wherein a plurality of networks are interconnected by way of a gateway or gateways. In a LAN (local area network) system, each network has a network number allocated thereto. In short, each device can be represented by a network number and a host number in a network to which the device belongs. In order to perform communications between different networks, a routing table in which an address of an inter-network router for transferring a datagram to a network of an object host is stored must necessarily be provided. In a computer network system, a network number may be set upon installation of a server, but in a consumer AV (audio and video) network system, it must be estimated that insertion or removal of a device into or from a network may take place frequently or a plurality of networks may be connected arbitrarily. In this instance, it is difficult to register a network number every time. It is an aim of the present invention to provide a network system wherein any device in all networks can be represented using addresses (relative addresses) set in the individual networks without relying upon the concept of a network number. EP-A-0,300,350 discloses a network system according to the preamble of claim 1. According to the present invention, there is provided: A network system, comprising: a plurality of networks each including one or more devices (A-H); and one or more gateways for connecting said networks to each other; characterised in that: a pass from within one of said networks to a device in another one of said networks is represented using addresses allocated, in said one of said networks, to said devices and said gateways in said networks. In the network system, a pass from within one of the networks to a device in another one of the networks is represented using the addresses allocated to the devices and the gateways individually in the networks, and accordingly, any device in the entire network system can be indicated using the addresses set in the individual networks without relying upon the concept of a network number. Consequently, it is not necessary to register a network number every time a network is connected. Further, when viewed from any given one of the devices, a pass therefrom can be taken in a hierarchic structure, and no complicated routing control is required. Incidentally, routing control requires a table in which passes between different devices are stored, and when a device or devices are to be provided additionally, modification to the table or the like is required. It is to be noted that the present invention is suitably applied to a system wherein the number of networks involved and the number of devices connected in each network are not so great such as a consumer audio and video network system. This is because, as the number of networks and the number of devices increase, the number of steps in a procedure of search increases progressively, and consequently, the search is complicated and requires much time. The features and advantages of the present invention will become more apparent from the following description of an exemplary embodiment and the accompanying drawings in which: FIG. 1 is a block diagram showing a general construction of a network system to which the present invention is applied; FIG. 2 is a diagrammatic view showing a construction of a packet for use with data communication in the network system; and FIGS. 3 and 4 are flow diagrams illustrating a procedure of search in the network system together with contents of communication in the procedure. In the drawings, like parts or elements are denoted by like reference characters. Referring first to FIG. 1, there is shown a general construction of a network system to which the present invention is applied. The network system shown includes three networks 1, 2 and 3. In each of the networks 1, 2 and 3, each device has a relative address allocated thereto. The network 1 includes three devices A, B and C to which the addresses of "1", "2" and "3" are allocated, respectively. The network 2 includes three devices D, E and F to which the addresses of "1", "2" and "3" are allocated, respectively. Further, the network 3 includes two devices G and H to which the addresses "1" and "2" are allocated, respectively. The networks 1 and 2 are connected to each other by way of a gateway GW1, and the networks 2 and 3 are connected to each other by way of another gateway GW2. Also the gateways GW1 and GW2 have addresses of the respective associated networks allocated thereto. Here, the address of the gateway GW1 on the network 1 is "4"; the address of the gateway GW1 on the network 2 is "5"; the address of the gateway GW2 on the network 3 is "4"; and the address of the gateway GW2 on the network 3 is "3". FIG. 2 shows a construction of a packet for use with data communication. The packet shown is generally constituted a destination address, a source address and a message. Subsequently, description will be given of how a pass from within one of the networks to another certain device in another one of the networks in an attempt to search the certain object in the entire network system is represented in the network system described above. It is assumed that, for example, the device A makes a source of a video signal and tries to search a device which can record a video signal. For such search, broadcasting (BC) in the network system is used. Here, the address to which broadcasting is directed is represented by . It is assumed here that the devices C, E, F and H indicated by slanting lines in FIG. 1 are devices which can record a video signal, that is, recordable machines. FIGS. 3 and 4 illustrate a procedure of search and contents of communication in such search. Referring first to FIG. 3, the device A first broadcasts "ASK ANY RECORDABLE MACHINE TO RESPOND" (step 101). The contents of communication then are "" for the destination address, "1" for the source address and "ASK ANY RECORDABLE MACHINE TO RESPOND" for the message (packet 201). The device C in the network 1 to which the device A belongs responds to the broadcast of the device A (step 102). The contents of communication then are "1" for the destination address, "3" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 202). Consequently, the device C is found out as a recordable machine, and the address "3" indicates the pass from the device A to the device C. Then, the device A broadcasts "ASK ANY GATEWAY TO RESPOND" (step 103). The contents of communication then are "" for the destination address, "1" for the source address and "ASK ANY GATEWAY TO RESPOND" for the message (packet 203). The gateway GW1 connected to the network 1 to which the device A belongs responds to the broadcast of the device A (step 104). The contents of communication then are "1" for the destination address, "4" for the source address and "THIS IS A GATEWAY" for the message (packet 204). In response to the gateway GW1, the device A then broadcasts "ASK ANY RECORDABLE MACHINE TO RESPOND" to the network ahead of the gateway GW1 (step 105). The contents of communication then are "4." for the destination address, "1" for the source address and "ASK ANY RECORDABLE MACHINE TO RESPOND" for the message (packet 205). In response to the broadcast of the device A, the gateway GW1 transmits it to the network 2 (step 106). The contents of communication then are "" for the destination address, "5.1" for the source address and "ASK ANY RECORDABLE MACHINE TO RESPOND" for the message (packet 206). In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. Here, the address "5.1" represents the address "1" in the network ahead of the address "5". Such representation similarly applies in the following description. The device E in the network 2 responds to the packet (step 107). The contents of communication then are "5.1" for the destination address, "2" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 207). In response to the response of the device E, the gateway GW1 transmits it to the network 1 (step 108). The contents of communication then are "1" for the destination address, "4.2" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 208. In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. Consequently, the device E is found out as a recordable machine, and the address "4.2" indicates the pass from the device A of the network 1 to the device E of the network 2. In this manner, the pass is represented in a hierarchic representation. Also the device F in the network 2 responds to the transmission of the message from the gateway GW1 to the network 2 at step 106 (step 109). The contents of communication then are "5.1" for the destination address, "3" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 209). In response to the response of the device F, the gateway GW1 transmits it to the network 1 (step 110). The contents of communication then are "1" for the destination address, "4.3" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 210). In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. Consequently, the device F is found out as a recordable machine, and the address "4.3" indicates the pass from the device A of the network 1 to the device F in the network 2 and is represented in a hierarchic representation. Subsequently, referring now to FIG. 4, the device A broadcasts "ASK ANY GATEWAY TO RESPOND" to the network ahead of the gateway GW1 (step 111). The contents of communication then are "4." for the destination address, "1" for the source address and "ASK ANY GATEWAY TO RESPOND" for the message (packet 211). In response to the broadcast of the device A, the gateway GW1 transmits it to the network 2 (step 112). The contents of communication then are "" for the destination address, "5.1" for the source address and "ASK ANY GATEWAY TO RESPOND" for the message (packet 212). In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. The gateway GW2 connected to the network 2 responds to the message (step 113). The contents of communication then are "5.1" for the destination address, "4" for the source address and "THIS IS A GATEWAY" for the message (packet 213). In response to the response of the gateway GW2, the gateway GW1 transmits it to the network 1 (step 114). The contents of communication then are "1" for the destination address, "4.4" for the source address and "THIS IS A GATEWAY" for the message (packet 214). In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. In response to the message, the device A broadcasts "ASK ANY RECORDABLE MACHINE TO RESPOND" to the network connected to the gateway GW2 (step 115). The contents of communication then are "4.4." for the destination address, "1" for the source address and "ASK ANY RECORDABLE MACHINE TO RESPOND" for the message (packet 215). In response to the broadcast of the device A, the gateway GW1 transmits it to the network 2 (step 116). The contents of communication then are "4." for the destination address, "5.1" for the source address and "ASK ANY RECORDABLE MACHINE TO RESPOND" for the message (packet 216). In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. In response to the message, the gateway GW2 transmits it to the network 3 (step 117). The contents of communication then are "" for the destination address, "3.5.1" for the source address and "ASK ANY RECORDABLE MACHINE TO RESPOND" for the message (packet 217). In this manner, the gateway GW2 transmits the message modifying the destination address and the source address. Here, the address "3.5.1" indicates the address "1" of the network ahead of the address "5" of the network further ahead of the address "3". Such representation similarly applies to the following description. The device "H" in the network 3 responds to the message (step 118). The contents of communication then are "3.5.1" for the destination address, "2" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 218). In response to the response of the device H, the gateway GW2 transmits it to the network 2 (step 119). The contents of communication then are "5.1" for the destination address, "4.2" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 219). In this manner, the gateway GW2 transmits the message modifying the destination address and the source address. In response to the message, the gateway GW1 transmits it to the network 1 (step 120). The contents of communication then are "1" for the destination address, "4.4.2" for the source address and "THIS IS A RECORDABLE MACHINE" for the message (packet 220). In this manner, the gateway GW1 transmits the message modifying the destination address and the source address. Consequently, the device H is found out as a recordable machine, and the address "4.4.2" indicates the pass from the device A of the network 1 to the device H of the network 3. In this manner, the pass is represented in a hierarchic representation. The device A can find out the devices C, E, F and H as recordable machines in such a manner as described above. In short, the device A can find out the addresses of and accordingly the passes to the devices C, E, F and H. It is to be noted that, while FIGS. 3 and 4 illustrates a search for a recording machine up to the network 3, a gateway of the network 4 is searched after that. In this instance, since there is no response to the search, it is determined that there is no network connected ahead of the network 3 and the search is ended. In this manner, in the network system of the present embodiment wherein the networks 1 to 3 are connected to each other by way of the gateways GW1 and GW2, a pass from within a network to a device in another network is represented in a hierarchic representation using addresses allocated to the devices and the gateways in the individual networks. It is to be noted that the system configuration of the network system of the embodiment described above is a mere example and naturally the number of networks and the number of devices belonging to each network are not limited to those of the embodiment. Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the scope of the invention.

Claims: A network system, comprising: a plurality of networks each including one or more devices (A-H); and one or more gateways (GW1, GW2) for connecting said networks to each other; characterised in that: a pass from within one of said networks to a device in another one of said networks is represented using addresses allocated, in said one of said networks, to said devices and said gateways in said networks. A network system according to claim 1, wherein each of said gateways (GW1, GW2) has a function of modifying an address in communication between adjacent ones of said networks. A network system according to claim 1 or 2, wherein said devices (A-H) include a recording machine or machines and/or a reproducing machine or machines. A network system according to claim 1, 2 or 3, wherein the pass is represented in a hierarchic representation. A network system according to any one of the preceding claims, further comprising means for generating a broadcast in one of said networks to search for an object device. A network system according to any one of the preceding claims, further comprising means to search for gateway (GW1, GW2) prior to a broadcast from a source device to another one of said networks. A network system according to claim 6, wherein said means to search a gateway are adapted to end the search for the object device when no response is detected as a result of the search for a gateway (GW1, GW2).

Inventors: KAWAMURA HARUMI, OGAWA KAZUYUKI, SHIMA HISATO, YAMAZAKI HIROSHI, KAWAMURA, HARUMI, OGAWA, KAZUYUKI, SHIMA, HISATO, YAMAZAKI, HIROSHI, KAWAMURA, HARUMI, C/O SONY CORPORATION, OGAWA, KAZUYUKI, C/O SONY CORPORATION, SHIMA, HISATO, C/O SONY CORPORATION, YAMAZAKI, HIROSHI, C/O SONY CORPORATION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1993
Main classification: H04L12
IPC codes: H04L12