JPH0728308B2 - Communication network interconnection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention installs a plurality of communication networks for communicating by packets having a destination address, in particular, a local area network (hereinafter abbreviated as LAN), and between them. Communication network interconnection device (hereinafter abbreviated as bridge) used when it is necessary to communicate with each other
It is about.

[Prior Art] With the increasing use of communication networks, especially LANs, a large number of LANs will be used within one campus. This is often done because the transmitted traffic is not divided and the efficiency of each LAN is not reduced, or for operational reasons.
Even in that case, it is required to realize a communication function between LANs. In recent years, when connecting LANs to each other, MAC
The so-called MAC bridging method, which performs relay processing using a (media access control) layer protocol, is drawing attention in terms of transmission performance.

FIG. 10 is a block diagram showing an example of a system to which a conventional bridge is applied. In FIG.
1a) and (101b) are connected to each other by a trunk LAN (103), and medium-low speed LANs (102a) and (102b) connected to the bridges (101a) and (101b) include terminal devices (104a) to (104a). 104
n) and (107a) to (107n) are connected.

The bridges (101a) and (101b) have the same structure. First
FIG. 11 is a block diagram showing the configuration of the one bridge (101), which includes an access control unit (11
0), access control unit (111) of main LAN (103), medium and low speed
Terminal devices (104a) to (104n) connected to the LAN (102a)
An address filter (112) having a table having addresses of the elements, a data buffer (113) connecting the access control units (110) and (111), and a received packet from the trunk LAN (103) are a medium-low speed LAN (102a). ) Is notified from the address filter (112) that the packet is written in the data buffer (113), and a control means (instruction is given to the access control unit (110) of the medium to low speed LAN to pass the packet ( 114) and.

FIG. 12 is a diagram showing a general packet format, which includes a preamble (31), a start delimiter (32), a frame control (3
3), destination address (34), source address (35), information field (36), frame check sequence (3
7), with a delimiter (38) at the end.

Next, the operation will be described. When sending a packet from the terminal device (104a) to the terminal device (107a), the bridge (101a)
Sends out the packet from the terminal device (104a) received from the medium-low speed LAN (102a) to the trunk LAN (103), and the bridge (10
1b) receives the packet from the trunk LAN (103)
After determining that the packet is addressed to the terminal device (107a) on the LAN (102b), the packet is sent to the medium to low speed LAN (102b) connected to the terminal device (107a).

[Problems to be Solved by the Invention] Since the conventional communication network interconnection device is configured as described above, three or more LANs cannot be interconnected. In addition, JP-A-64-65949, "MAC
The control method for connecting multiple LANs described in "Bridge control method" is intended for hierarchical addresses, which is one of the address assignment methods, and is applicable to commonly used flat addresses. There was a problem that it could not be done.

The present invention has been made to solve the above-mentioned problems, and it is possible to connect three or more LANs adopting a flat address to each other, and to have a small number of components that require high-speed operation. The object is to obtain a communication network interconnection device with high performance and low power consumption.

[Means for Solving the Problems] A communication network interconnection device according to the present invention is
A plurality of LAN interfaces with an address table that connects the LANs and the addresses of the terminal devices connected to the LAN, and the route that contains the addresses of the terminal devices connected to all the above LANs And a route control unit having a control table.

[Operation] The communication network interconnection device according to the present invention is
Receives a packet transmitted on the LAN, and refers to the address table provided in the LAN interface, and the packet is addressed to the LAN, that is, whether the communication partner exists on the same LAN or another LAN. If it is the former, the packet processing is terminated, and in the latter case, the packet is sent to the route control unit, and the route control unit refers to the route control table to identify which LAN the packet is addressed to, By transmitting the packet to the LAN interface and transmitting the packet to the connected LAN, it is possible to greatly reduce the number of packets to be subjected to the route control processing.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 is a block diagram showing a system to which a bridge according to the present invention is applied. In FIG. 1, LAN (2a), (2b) ... (2n) are connected to bridge (1), and LAN (2 2a), LAN (2b) ... LAN (2n) has a terminal device (11
a) to (11n), (12a) to (12n) ..., (16a) ... (16n)
Are connected. This LAN (2a), LAN (2b) ..., LAN (2
n) may be the same LAN or different LANs.

However, in order to perform mutual communication by the bridge, the basic packet forms must be of the same type.
For example, at least each packet must have a destination address.

Figure 2 shows the LAN as the international standard ISO8802-5 (token ring).
2 shows a ring type case as defined by the above, and at least two transmission lines (2a-
1) and (2a-2) are connected to the bridge (1).

Figure 3 shows the case where the LAN is a bus type as defined by the international standard ISO8802-3 (CSMA / CD) or ISO8802-4 (token bus). At least one transmission line (2a-1 ) Is connected to the bridge (1).

The connection configurations shown in FIGS. 2 and 3 may be mixed in one bridge (1).

FIG. 4 is a block diagram showing the configuration of the bridge (1), which is an address table (22a) having addresses of terminal devices connected to the LAN (2a), LAN (b) ..., LAN (2n) as elements. , (22b) ..., (22n) and connected to each LAN (2a), (2b) ..., (2n) for access control L
AN interfaces (21a), (21b) ..., (21n), packet queues (23a), (23b) ..., (23n) provided on the output side of each LAN interface, and an input side of each LAN interface Packet queue (24a), (24b)
, (24n), the multiplexing control (25) that extracts and outputs the packet stored in each packet queue, and the destination address of the packet input from this multiplexing control unit (25), The route control unit (26) that determines whether or not the route is determined and outputs the determination result as route control information, and the route is determined by including the contents of each address table (22a), (22b) ..., (22n). The route control table (27) provided in the route control unit (26) and the packet output by the route control unit (26) are used to identify the above-mentioned route control information attached thereto. , Corresponding packet queue (24a), (24b) ...,
(24n) or a distribution control unit (28) that distributes the packet to a plurality of packet queues.

In FIG. 4, address tables (22a), (22b), (22
n) and Ta, Tb, Tn described in the route control table (27) indicate only the inclusive relation of the table information, and do not mean the table configuration method such as the arrangement order. Also, each
Terminal devices (1 connected to LAN (2a), (2b), (2n)
1a) to (11n, (12a) to (12n) ... (16n) to (16n) are assigned addresses # 35, # 25, # 81, # 67, # 24, and # 56.

FIG. 5 is an example of an address table (22a) realized by using a random access memory (hereinafter, abbreviated as memory), which is a terminal device (11a) to a LAN (2a).
(11n) addresses # 35 and # 23 are registered.

FIG. 6 shows an example in which the address table (22a) is realized by a CAM (content addressing memory), and contains the same information as in the case of using the memory shown in FIG.

Figure 7 shows the route control table (2
It is an example of 7), and a memory defined so that the addresses of the terminal devices (11a) to (11n) ... (16a) to (16n) connected to each LAN (2a) to (2n) correspond to each LAN. It is registered in the area.

FIG. 8 shows an example of the case where the route control table (27) is realized by CAM (content addressing memory).
All the addresses of the terminal devices connected to are stored, and at the same time, the identification information of the LAN corresponding to the address of each of the terminal devices is stored. Next, the operation of the above-described embodiment is performed by LAN (2
The operation when the terminal device (11n) connected to a) communicates with the terminal device (12n) connected to the LAN (2b) will be described.

FIG. 9 shows the packet transmitted at this time.
Address # 67 is set as the destination address (34), and address # 23 is set as the source address (35).

First, the terminal device (11n) sends out a packet on the LAN (2a). This packet is received by the LAN interface (21a). At this time, if LAN (2a) is a ring LAN, LA
The N interface (21a) copies the packet while performing a relay operation in the LAN (2a). If the LAN (2a) is a bus type LAN, the packet is transmitted to all terminal devices in the LAN (2a) regardless of the receiving operation of the LAN interface (21a).

The LAN interface (21a) receiving the packet identifies whether the packet is addressed to the terminal device in the LAN (2a) or not. This function is generally called address filtering.

When the LAN interface (21a) has the address table shown in FIG. 5, the LAN interface (21a) reads the memory of the address table in the order of addresses and compares it with the destination address of the received packet. Discard it, and if there is no match, identify it as a packet destined for another LAN and output it to the packet queue (23a). In this case, the destination address of the packet is the address #
67, which is not registered in the address table (22a) shown in FIG. 5, so this packet is output to the packet queue (23a).

When the LAN interface (21a) has the CAM shown in FIG. 6, the LAN interface (21a) inputs the destination address to the CAM and performs the above-mentioned identification by checking the output of the CAM, which is the match or mismatch output. .

When the multiplexing controller (25) detects that a packet is input to the packet queue (23a), it extracts the packet and transfers it to the route controller (26). The multiplexing control unit (25) constantly monitors all the packet queues (23a) to (23n) and the route control unit (26), and there is accumulation in the packet queue.
In addition, if the route control unit (26) is in a packet processable state, the packet is extracted from the packet queue and transmitted to the route control unit (26).

When the route control unit (26) receives the packet from the multiplexing control unit (25), the route control unit (26) identifies the destination address and determines the route, that is, which LAN the packet is addressed to. Route controller (2
If 6) has the route control table (27) shown in FIG. 7, the memory shown in FIG. 7 is read in the order of memory addresses, and a match / mismatch check is performed. Determine the LAN to send. In this case 101
If the address information stored in the address matches, 101
Since the address is in the table range corresponding to LAN (2b), it can be identified and determined as a packet of LAN (2b). Further, when the route control unit (26) has the route control table (27) by the CAM shown in FIG. 8, the route control unit (26)
Enter the destination address into the CAM and the match is the output of the CAM,
Inspects mismatch output and if there is a match, CAM
The LAN to be sent is determined by the route tag information output from. In this case, since the address # 67 is stored, the coincidence / non-coincidence output indicates coincidence, and it is possible to identify and determine the packet addressed to the LAN (2b) from the stored route tab information. The route control unit (26) should send
When the LAN is determined, the packet indicating the LAN to be transmitted is added and the packet is transmitted to the distribution control unit (28). The distribution control unit (28) uses the packet queue (2
Output the above packet to 4b).

When the LAN interface (22b) detects that there is a packet to be sent to the packet queue (24b), it extracts it and sends it to the LAN (2b). Finally, the terminal device (12n) receives the packet.

In the above embodiment, the address table (22a) and the route control table (27) are explained using the memory and the CAM. However, in the case of using the memory, a search for a hash or the like that is commonly used is used. Techniques can also be used. Further, although the case of the LAN has been described in the above embodiment, a general communication network using a packet may be used, and the same effect as that of the above embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, each of a plurality of communication network interfaces that connect a communication network is provided with an address table whose elements are addresses of terminal devices connected to the communication network, Since the route control unit is configured to have the route control table having the addresses of the terminal devices connected to all the above communication networks as elements, the address table is searched first to relay to another LAN. There is a two-step address inspection to determine whether or not there is a need, and to perform route control only on the packet that needs to be relayed next, and statistically determine the number of packets subject to route control processing. It can also be significantly reduced on average, and it is a high-performance communication network that interconnects many communication networks. There is an effect that the interconnection device can be realized with a small size and low power consumption, since the number of components required to operate at high speed is small.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system to which a communication network interconnection device according to an embodiment of the present invention is applied, and FIG.
Figure is a block diagram showing the connection between the LAN and the bridge when the LAN is a ring type, Fig. 3 is a block diagram showing the connection between the LAN and the bridge when the LAN is a bus type, and Fig. 4 is a block showing the configuration of the bridge. 5 and 5 are explanatory views of the address table realized by using a memory, and FIG. 6 is the CA of the address table.
FIG. 7 is an explanatory diagram of a case realized by M, FIG. 7 is an explanatory diagram of a route control table realized by using a memory, FIG. 8 is an explanatory diagram of a case where the route control table is realized by CAM, and FIG. FIG. 10 is a block diagram of a system to which a conventional bridge is applied, FIG. 11 is a block diagram of a conventional bridge, and FIG. 12 is a packet transmitted in a conventional device. FIG. In the figure, (1) is a bridge (communication network interconnection device), (2a) to (2n) are LANs, and (11a) to (11).
n), (12a) to (12n) ... (16a) to (16n) are terminal devices, (21a), (21b) to (21n) are LAN interfaces,
(22a), (22b) to (22n) are address tables, (23
a), (23b) to (23n), (24a), (24b) to (24n) are packet queues, (25) is a multiplexing control unit, (26) is a route control unit, and (27) is a route. A control table, (28) is a distribution controller. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A plurality of communication networks that communicate by a packet having a destination address are connected via a communication network interface provided corresponding to each communication network, and a packet transmitted on the communication network is received. A communication network interconnection device for determining a destination of a packet and outputting the packet to a target communication network, wherein the interconnection device includes one route control unit, and the communication network interface is a terminal connected to the communication network. A communication network interconnection device comprising a table having elements of device addresses, and the route control unit having a table having elements of addresses of terminal devices connected to all the communication networks.