JPS6074842A - Local area network - Google Patents

Abstract

PURPOSE:To reduce the overhead of communication by having a mutual connection between the high-order and low-order networks connected to the high- order and low-order stations respectively via a gateway, and providing a memory to said gateway to decide an applicating protocol by the contents of the memory. CONSTITUTION:Stations 11 and 12 are connected to an high-order network N1; while stations 21, 22, 31 and 32 are connected to low-order networks N2 and N3 respectively. The mutual connections are fed among networds N1 and networks N2 and N3 respectively via gateways G112 and G113. Then memories 51 and 61 are provided to the gateways G112 and G113 respectively, and tables are provided to these memories to show the application to be given to an high-order or low-order protocol according to the address of each station to be defined as the final transmitting destination. Then an applicating protocol corresponding to the address of the final station showing the final transmitting destination is decided based on the contents of said tables. Thus the overhead can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a local area network having a two-level protocol hierarchy.

[Technical background of the invention]

In recent years, local area networks (LANs) have been developed to interconnect computers and terminals located within the same pill, factory, or premises.
) has become popular as an effective means of communication. As an example of this type of local area network, a network N1 to which an upper level protocol is applied and a network N2 to which a lower level protocol is applied are exemplified. Figure 1 shows the system configuration of a large-scale local area network consisting of N3. As mentioned above, network N1 and network N
2. The communication protocol is different from N3. Therefore, network N1 and network N2. In order to interconnect N3, K requires a gateway G12,013 that performs protocol conversion for both networks.

Note that 11.12 is a station connected to network N1,
21.22 is a station connected to network N2; 31.22 is a station connected to network N2;
32 is a station connected to network N3.

Generally, within the same network, communication is performed using the same level of protocol specific to the network. Figures 2(a) and 2(b) are for explaining this protocol. Figure 2(a) shows the protocol for the network (upper network) NJ, and Figure 2(b) shows the protocol for the network (lower network). )N2. The N3 protocol is shown. As is clear from the figure, the protocol (upper protocol) of the network N1 is a pair of transmission (5end) and arrival confirmation (Confirm). On the other hand, network N2. The N3 protocol (lower protocol) is only for transmission (5th end). Therefore, lower network N2. Communication between N3, e.g. station 2
In the case of communication between 1.31, station 21 and gateway 012
Communication between the gateway G13 and the station 31 is performed using the lower protocol shown in FIG. 2(b), and communication between Dartway 012.913 is performed using the upper protocol shown in FIG. 2(a) K. . This state is shown in FIG.

[Problems with background technology]

As described above, in a conventional local area network having a two-level protocol layered structure, communication between lower-level networks is mediated by an upper-level protocol. This has the disadvantage of causing protocol overhead in communication between networks. [Objective of the Invention] This invention was made in view of the above circumstances, and its purpose is to reduce the protocol overhead in communication between lower-level networks, thereby increasing the communication speed. The objective is to provide a local area network that can achieve high speeds.

[Summary of the invention]

In this invention, in a local area network system in which upper and lower networks are interconnected by a dartway and has a two-level hierarchical structure of upper and lower protocols, each station address that can be the final transmission destination is A memory is provided in the dartway in which a table indicating whether the upper or lower protocol is applied is placed. When transmitting data, the dartway determines an applicable protocol corresponding to the final station address indicating the final destination based on the table in the memory, and performs communication according to the determined protocol. ] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Note that the same parts as in FIG. 1 are given the same reference numerals and detailed explanations are omitted. The local area network shown in FIG. 4 includes an upper network N1 and a lower network N2, as in FIG. Consists of N3. The upper network N and the lower network N2 are interconnected by a gateway 0112 equipped with a memory 51. Further, the upper network N1 and the lower network N3 are interconnected by a gateway G113 equipped with a memory 61. The memory 51.61 indicates the station address of each station that can be the final destination (final station address), the station address of the station that is the direct destination, and whether or not the direct transmitting station is Dartway. There is an address table showing correspondence with information.

Next, the internal configuration of the gateway 0112 will be explained using FIG. 5. Regarding gateway G113, (
I want it to be read by replacing it with the symbols in parentheses). In addition to the memory 51 (61), the Dartway G112 (G11B) has an interface 52 (62) with the upper network NJ (N1), an interface s s (es) with the lower network N2 (N3), and a gateway. The processing device 54 (which is the center of G112 (0113)
64). These memory 5J (6]), interface 52 (62).

53 (63) and processing device 54 (64) are coupled by an internal path 55 (65).

Here, the operation of one embodiment of the present invention will be described in FIG.
This will be explained with reference to the communication sequence chart shown in b). Now, assume that data is to be transmitted from station 21 in lower network N2 to station 31 in another lower network N3. In this case, lower network N2. Communication between N3 is performed via the upper network N1. Station 21 uses destination station 3 in lower network N3 as the final station address.
1, and the station address of the gateway G112 (which interconnects the lower network N2 to which it belongs and the upper network N1) is specified in the transmission data as the station address of the direct destination. Thus, the transmission data from the station 21 is sent to the gateway 0112 via the lower network N2 (see FIG. 6(a)).

When the processing device M, s4 of the dartway 0112 receives the transmission data from the station 21 (from the interface 53), it refers to the address table in the memory 51. As in this example, when the final station address indicates station 31 (belonging to lower network N3, which is a different network from upper network N1), the above address table includes station 31.
Corresponding to the address of station 0, the address of Dartway 01130, which should be the direct destination, is written. Furthermore, information indicating that the station address is a dartway station address (not a normal station) is added to the station address of the dartway G113 written in correspondence with the station address of the station 31. As a result of referring to the address table, the processing device 54 determines that the direct destination is the gateway G113 based on the above-mentioned additional information, and then decides to perform communication using the lower protocol. Therefore, the processing device 54 creates transmission data to which information indicating that arrival confirmation is not required (lower protocol is applied) is added. This transmission data also includes address information in which the direct destination is the gateway G113 and the final destination is the station 31.

The transmission data created by the processing device 54 is sent to the upper network N1 via the interface 52. Transmission data from the Dartway G112 (processing device 54 therein) is then sent to the Dartway 0113 via the upper network N1 (see FIG. 6(, )).

If the data transmitted from Dartway G112 contains information indicating that arrival confirmation is not required (lower level protocol is applied), R-Tway G113 returns to the destination station (in this example) without performing an arrival confirmation response. Then, the data is transmitted to the station 31) (see FIG. 6(, )).

In this way, in this embodiment, the upper network N1
Lower network N2. In communication between N3, Dartway G in upper network N1
112. Communication between G113 is performed according to a lower-level protocol.

Next, the operation when transmitting data from the station 21 in the lower network N2 to, for example, the station 1 in the upper network Nl will be explained. In this case, when station 21 specifies the address of destination station 11 in upper network N1 as the final station address, A+ w Tl1JG w % /jt 4
y Ro-r LI I/ -x L + -r AJ
The station address of L-way G112 is specified in the transmission data. Transmission data from the station 21 is then sent to the gateway 0112 (see FIG. 6(b)). When the processing unit R54 of the Dartway G112 receives the transmission data from the station 21, it refers to the address table in the memory 51. As in this example, when the final station address indicates station 11 (a tree belonging to upper network N1), the above address table has an address that matches the station address corresponding to the station address of station 110 as the direct destination. It is written as the station address of the target station. This direct destination station address has information added to it indicating that the station address is that of a regular station (not Dartway) (unlike the case of communication between stations 21 and 31). There is. As a result of referring to the address table, the gateway G112 (its processing device 54) determines that the direct destination is not the f-way G113 based on the additional information described above, and then decides to perform communication using the upper protocol. Dartway G112 then creates transmission data to station 11. This transmission data includes the dartway 113 mentioned above.
Unlike the data sent to , it does not include information indicating that arrival confirmation is not required (lower protocol is applied). f
-) Transmission data from way 0112 is sent to station 11 via upper network N (see Figure 6(b))
. Station 11 (higher network NIK other than Dartway)
The station to which it belongs is configured to communicate according to the upper layer protocol, and upon receiving the transmission data from the gateway G112, it sends an arrival confirmation (Confirm
) returns the response to Dartway 0112. dirt way 0
112 is in a waiting state for an arrival confirmation response after sending out the transmission data because of communication using the upper protocol, and ends the transmission sequence upon receiving an arrival confirmation response from the station 11.

In addition, in the embodiment described above, a local area network consisting of a network with a loop structure was explained.
This invention is based on the path structure.

It can also be applied to local area networks consisting of networks other than loops, such as networks.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to reduce the protocol overhead of communication within the upper network, which involves communication between lower networks via the upper network, thereby increasing the speed of communication.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the system configuration of a conventional local area network, Figure 2 is a diagram explaining communication within the same network in the local area network shown in Figure 1, and Figure 3 also explains communication between lower-level networks. FIG. 4 is a diagram showing the system configuration of a local area network according to an embodiment of the present invention, FIG. 9 is a block diagram showing the internal configuration of the dartway shown in FIG. 4, and FIG. It is a communication sequence chart for explaining operation. 11.12.21m22, 31.32... station, sl,
61...Memory, 54.64...Processing device, N1.
... Upper network, N 2 t N 3 ... Lower network, G112. G113...Dirtway. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 End Figure 4

Claims (1)

[Claims] In a local area network system in which upper and lower networks are interconnected by a dartway and has a two-level hierarchical structure of upper and lower protocols, each station that can be the final destination is connected to the above f-) way. A table card device memory that indicates whether to apply the upper or lower protocol corresponding to the station address, and a table memory that indicates which protocol to apply corresponding to the final station address that indicates the final destination based on the table in this memory. A local area network having a means for determining the protocol and performing communication according to the protocol.