JP2969736B2 - Network connection device - Google Patents

Description

The present invention relates to a network connection device, and particularly to an OSI (Open System) which is an international standard network architecture.
The present invention relates to a network connection device for connecting networks having different MAC address systems of a standard protocol of Interconnection.

[Conventional technology]

The OSI protocol hierarchy is, for example, IEICE Handbook Vol. 26, Network Architecture Division I
As described in Chapter 3.4, page 1900, it is divided into seven layers. That is, from the lower layer to the physical layer (hereinafter referred to as 1)
Layer), data link layer (hereinafter referred to as two layers), network layer (hereinafter referred to as three layers), transport layer (hereinafter referred to as four layers), session layer (hereinafter referred to as five layers), presentation layer (hereinafter referred to as six layers) Application layer)
Layer). In addition, two layers
Divided into two sub-layers, and MAC (Media acces
s control) sub-layer and LLC (Logical link control) sub-layer. Furthermore, when connecting heterogeneous networks with different protocols, depending on where the above-mentioned layers 1 to 7 differ, for example, see “Key to Realizing MAPFA” on page 255, International Robotics / FA Center Edition, published by the Japan Standards Association. As described, at present, FIG. 5 (a),
As shown in the explanatory diagrams of (b) and (c), there are three types of network connection devices of a bridge type, a router type, and a gateway type.

In the bridge type shown in FIG. 5A, the protocol of the network A on the left side and the protocol of the network B on the right side are different in the physical layers A and B and the MAC sublayers A and B, respectively. This is a model in which two networks having the same MAC sublayer address system are connected by relaying in the LLC sublayer.

The router type shown in FIG. 5 (b) is a model in which the physical layer and the data link layer of the first and second layers are different, but the network layer and above are connected by relaying the same two networks at the network layer.

The gateway type shown in FIG. 5 (c) is a model in which all seven layers A and B connect two different networks. In the case of the router type and the gateway type, the address systems of the MAC sublayers of the two networks to be connected may be different from each other.

6 (a), 6 (b) and 6 (c) show the function and signal flow of each layer of the above connection device. These are all examples when relaying from the A side to the B side. In the case of the reverse direction, the functions of the layers corresponding to A and B are alternated and the relay is performed.
FIG. 3 shows a format of a signal transmitted on the network. To be precise, since various control information is added in each layer, the actual format is more complicated than that of FIG. 3, but here, only the data 213 and the respective addresses 210 to 212 necessary for explaining the operation of the connection device are described. It is written. Each time data passes through each layer in a node or a connection device, an address or control information is added or removed from the head of the data. Examples of these are "OSI-Computer Network for Tomorrow" by Kenichi Tabata, page 48 of the Japan Standards Association, or "OSI Protocol Picture and Reading Book" Kinji Ono, Yoshiyori Urano, Kenji Suzuki, Kazunori Matsuo, Ohmsha, page 32
Is described in

[Problems to be solved by the invention]

The conventional network connection device described above is, for example, a fourth device.
As shown in the connection diagram of FIG.
, Each of the two networks supports at least a node (node A11, node C16) supporting the first to third layers of OSI, and the first and second layers of OSI, and at least It is assumed that the three layers have nodes (nodes B12 and D17) not provided. The same protocol is used in the same layer of each node on the A network. For example, the first layer of the node A and the first layer of the node B are the same. The same applies to each node on the B network. Also, the protocol hierarchy 150 of the 3rd to 7th layers of the node on the A network and the 3rd
The protocol layers 150 of the first to seventh layers are the same, and the protocol layers 151 of the first and second layers of the node on the A network are different from the protocol layers 152 of the first and second layers of the node on the B network. A network and B
In a network, the address system of the MAC sublayer is different.

Now, consider the communication between the nodes A and C and between the nodes B and D. Since the address systems of the MAC sublayers of the A network and the B network are different, a connection cannot be established with a conventional bridge. The conventional router type and gateway type can connect networks with different MAC sub-layer address systems, but have three layers because they use the information that three layers have when converting a MAC address. Node A and node C can communicate, but node B and node D, which do not have three layers, cannot communicate.

That is, in the conventional network connection device, when two networks having different MAC sub-layer address systems are connected by the connection device and communication is performed, communication between nodes having three layers is possible. There is a disadvantage that communication between nodes that do not have it is impossible.

An object of the present invention is to provide a MAC sublayer having a different address system.
A network connection device that connects two networks and enables communication between nodes having three layers in the same manner as before when viewed from the node, while also enabling communication between nodes without three layers. To provide.

[Means for solving the problem]

The network connection device of the present invention is a relay device for connecting data of communication between nodes having three layers in three layers in a connection device of two networks having different address systems of a MAC sublayer in the OSI7 layer model; One or more relay means for relaying data of inter-node communication having no layer in the LLC sublayer, and selecting these two or three or more relays by referring to the LSAP address of the data in the LLC sublayer And means for performing

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a flow chart showing the function of each layer and the flow of signals in one embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are configuration diagrams of the layers in this embodiment.

The connection device 1 has a layer configuration including a physical layer, a MAC sublayer, an LLC sublayer, and a network layer from the lower order. The physical layer and the MAC sublayer are each divided into A and B. In addition, as shown in FIG. 1, a relay function in the network layer and a relay function in the LLC sublayer are provided.
This is done by referring to the LSAP address in the sublayer.
One relay function is used for one data. The layer configuration of the connection device 1 viewed from the data differs depending on which layer the relay function is used. The layer configuration of the connection device 1 is LL
When the relay function of the C sub-layer is used, the result is as shown in FIG. 2A, and when the relay function of the network layer is used, the result is as shown in FIG. 2B.

In other words, the present invention operates so as to have the two-layer structure shown in FIGS. 2 (a) and 2 (b) because the LLC sublayer has the function as shown in FIG. However, FIG. 2 (a)
5 (a) and FIG. 2 (b) and FIG. 5 (b) have the same layer configuration, but differ in the function of the LLC sublayer. This is evident by comparing FIGS. 1 and 6.

That is, while the LLC sublayer of FIG. 5 (a) relays data while retaining the LAC address received from the lower MAC sublayer, the LLC sublayer of FIG. 2 (a) relays data using the LSAP address. After determining the MAC address, the MAC address is derived from the address information added in the application layer or determined uniquely from the LSAP address and relayed. The LLC sublayer of FIG. 5 (b) only removes and adds LSAP addresses, while FIG. 2 (b)
The LLC sublayer removes and adds the LSAP address after determining the relay function based on the LSAP address. To be exact,
The LLC sublayer of the connection device 1 has the function of the LLC sublayer 42 of FIG. Here, by judging the relay function based on the LSAP address, it looks like FIG. 2 (a) or (b).

Next, a signal flow when communication is performed from the node A to the node C or from the node B to the node D using the connection device 1 of the present invention in the connection device 2 shown in the connection diagram of FIG. The operation and usage of the LSAP address will be described. In the following description, the connection device 2 in FIG.

Data transmission from the A network 11 to the B network 15 is performed via the connection device 1, but data transmitted by the A network is transmitted to the physical layer A in the connection device.
It is passed in the order of MAC sublayer A and LLC sublayer. The LLC sublayer refers to the LSAP address in the data header to determine whether the data is output from the node A or the data output from the node B. Here, the former data includes the conventional ordinary LS
It is assumed that an AP address is added and an LSAP address different from the former is added to the latter data. Accordingly, the LLC sublayer determines the data, and if the former data is sent, sends the data to an upper network layer and relays it there. Then, by referring to the NSAP address,
After converting the MAC address, the data is transmitted to the B network. At this time, the connection device 1 has the layer configuration shown in FIG. 2 (b).

Next, if the LLC sublayer determines that the data is output from the node B, the LLC sublayer does not send the data to the network layer but relays the data within its own layer. And LSAP
The MAC address of the destination node is added based on the address or the address added in the upper layer of the LLC sublayer of the transmission source node, and transmitted to the B network. At this time, the connection device 1
Has the layer configuration of FIG. 2 (a).

The same applies to the communication from the node C to the node A or from the node D to the node B.

Also, when there are a plurality of types of nodes having the first and second layers but not having at least three layers as in the case of the node B or the node D, the relay function in the LLC sublayer is increased according to the type, and the LSAP address is used. By making the determination, communication becomes possible.

〔The invention's effect〕

As described above, the present invention provides a
The source / destination node and data protocol are identified by referring to the LSAP address. If the data is for communication between nodes having a network layer, the data is relayed at its own network layer as in a conventional router, and the MAC address is converted. If the data is for inter-node communication without a network layer, the data is relayed by its own LLC sublayer to obtain the MAC address of the data from a predetermined MAC address or address information added by the application layer of the transmission source in the data. By converting to a MAC address, communication between nodes with a network layer can be performed in the usual way,
This has the effect of enabling communication between nodes that do not have a network layer arranged on different networks.

[Brief description of the drawings]

FIG. 1 is a flowchart of one embodiment of the present invention, and FIG.
(B) is a layer configuration diagram of the present embodiment, FIG. 3 is a format diagram of a signal transmitted on a general network, FIG. 4 is a connection diagram of two networks by a connecting device, and FIG. ), (B), and (c) are layer configuration diagrams of a conventional network connection device, and FIGS. 6A, 6B, and 6C are flow charts of the conventional network connection device. 1,2 ... Connecting device, 3 ... Bridge type connecting device, 4 ...
Router type connection device, 5 ... Gateway type connection device, 10
…… A network, 11,12 …… Nodes AB, 15…
B network, 16, 17, ... Nodes C to D, 20, 27, 40, 5
0,60,70,81,86,91 ... Physical layer A, 23,30,45,54,66,85,9
0,99… Physical layer B, 21, 28, 41, 51, 61, 71, 82… MAC sublayer A, 24, 31, 44, 53, 65, 85… MAC sublayer B, 29, 42 , 52,83…
… LLC sublayer, 22, 62, 72… LLC sublayer A, 25, 64, 78… LLC
Sublayer B, 26, 43, 63, 73, 88 Network layer, 93 Network layer A, 97 Network layer B, 74, 94
Application layer A ~ Transport layer A, 76, 96 ... Application layer B ~
Transport layer B, 75,95 Application conversion, 82,92 Data link layer A, 89,98 Data link layer B, 150-152 Protocol layer, 200 Signal format, 210 MAC address, 211 LSAP address, 212 NSAP address, 213 data.

Claims (1)

(57) [Claims] 1. An apparatus for connecting two networks having different address systems of a MAC sublayer in an OSI7 layer model.
Relay means for connecting data of communication between nodes having three layers at three layers, one or more relay means for relaying data of communication between nodes having no three layers at an LLC sublayer, and an LLC sublayer Means for selecting one of these two or more relays by referring to the LSAP address of the data.