JP2823934B2 - Communication network connection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention installs a plurality of communication networks, particularly a local area network (hereinafter abbreviated as LAN), which performs communication by packets having a destination address, and establishes a network between them. The present invention relates to a communication network connection device (hereinafter abbreviated as a bridge) used when it is necessary to communicate with each other.

[Prior Art] As the use of communication networks, particularly LANs, progresses, a large number of LANs are used in one premises. This is often done for the purpose of not reducing the efficiency of each LAN by dividing the traffic to be transmitted, or for operational reasons.However, even in this case, it is required to realize the communication function between LANs. I have.

When interconnecting multiple medium- and low-speed LANs,
Conventionally, a method of installing a trunk LAN sufficiently faster than AN and connecting a medium to low speed LAN to the trunk LAN via a bridge has been used. The bridge in this case is two LAs with different speeds
Since N is connected, relay processing is performed using the MAC (media access control) layer protocol.

FIGS. 6 and 7 are block diagrams showing an example of a system to which a conventional bridge is applied. In FIG. 6, bridges (11) and (12) are connected to a main LAN (2). Medium- and low-speed LAN (3) connected to (11) and (12)
1) and (32) include terminal devices (41a) and (41b), respectively.
To (41n), (42a), (42b) to (42n) are connected. FIG. 7 is a block diagram showing the configuration of the bridge (11). The bridge (11) includes a medium-to-low speed LAN access control unit (51), a trunk LAN access control unit (52), and a medium / low speed LAN ( Terminal devices (41a) to (41n) connected to 31)
An address filter (53) having a table whose elements are the addresses, a data buffer (54) for connecting the access control units (51) and (52), and a packet received from the trunk LAN (2) is transmitted to a medium-to-low speed LAN (31). ) Is notified from the address filter (53), the packet is written in the data buffer (54), and the access controller (5
And control means (55) for instructing 1) to pass the packet. Since the bridge (12) has the same configuration as the bridge (11), illustration is omitted.

Next, the operation will be described. When sending a packet from the terminal device (41a) to the terminal device (42a), the bridge (11)
Sends the packet from the terminal device (41a) received from the medium / low speed LAN (31) to the main LAN (2), and the bridge (12) receives the packet from the main LAN (2) and receives the packet from the medium / low LAN (3).
2) After determining that the packet is addressed to the terminal device (42a) above, the packet is transmitted to the medium / low speed LAN (32) to which the terminal device (42a) is connected.

[Problem to be Solved by the Invention] Since the conventional communication network connection device is configured as described above, the LAN speed is higher than that of the workstation.
Is required. However, with the speeding up of workstations and the like, the speed of the LAN for connecting terminal devices has become the level of the conventional trunk LAN. Therefore, in order to interconnect such high-speed LANs, a higher-speed LAN is required, but realizing this high-speed performance is very expensive.

On the other hand, a control method for interconnecting a plurality of LANs with a bridge is disclosed in, for example, Japanese Patent Application Laid-Open No. 64-65949 "MAC bridge control method", but is intended for a hierarchical address which is one of the address assignment methods. However, there is a problem that the method cannot be generally applied to an address assignment method including a flood address.

The present invention has been made to solve the above problems, and regardless of the addressing method,
It is an object of the present invention to interconnect three or more LANs of the same speed with three or more bridges to obtain a communication network connection device which is economical and has flexibility of expansion.

[Means for Solving the Problems] A communication network connection device according to the present invention connects a plurality of communication networks performing communication by a packet having a destination address, receives a packet transmitted on the communication network, and receives the packet. A communication network connection device for determining a destination of a communication network and transmitting the communication network to a target communication network, comprising: a communication network interface individually connected to each of the plurality of communication networks; and a common bus interconnecting the communication network interfaces. A communication network interface comprising: an access control unit that controls access to its own communication network; a reception processing unit that sends reception data from the communication network obtained by the access control unit to the common bus; Above common bus A transmission processing unit for selecting only data addressed to the communication network from the above data and passing the data to the access control unit, wherein the transmission processing unit includes a table including an address of a terminal device connected to the communication network as an element And transmitting data using the internal bus in a time-division manner, wherein the transmission processing unit determines a data destination for a time slot assigned to a communication network interface other than its own communication network interface Is what you do.

[Operation] The communication network connection device of the present invention
The access control unit receives a packet transmitted on N, the reception processing unit reconfigures the packet according to the transmission speed of the common bus, and sends out the packet to the common bus. Of the packets from the LAN to the LAN to which it is connected by the address filter, and passes the selected packets to the access control unit, and the access control unit passes the packets to the LA to which it is connected.
By transmitting to N, three or more LANs of the same speed are interconnected, enabling economical and flexible expansion. Further, by using the common bus in a time-sharing manner, the time from when one data appears on the common bus to when reception ends can be determined.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a system to which a bridge according to the present invention is applied. In FIG. 1, a bridge (1) includes a common bus (7) and a plurality of buses connected to the common bus (7). LAN interface (61), (62), (6
3) and consists of:

LANs (31), (32) and (33) are connected to the LAN interfaces (61), (62) and (63), respectively.

Each of the LANs (31), (32), and (33) has a terminal device (41a) to (41n), (42a) to (42n),
(43a) to (43n) are connected.

In FIG. 1, the LAN (3
Although 1) to (33) are shown as bus types, other types of LAN such as a ring type may be used. FIG. 2 is a block diagram showing the configuration of one of the LAN interfaces (61) to (63) and the LAN interface (61), all of which have the same configuration.
N (31), an access control unit (81) for performing access control, a reception processing unit (82) for transmitting data received from the access control unit (81) to the common bus (7), 82), the access control unit (81)
Data reconstructing means (83) for reconstructing the packets received by the common bus (7) according to the transmission speed of the common bus (7), the common bus (7)
A transmission processing unit (84) that selects only data destined for the LAN (31) from the above data and passes it to the access control unit (81). The transmission processing unit (84) is provided in the transmission processing unit (84) and connected to the LAN (31). An address filter (85) having a table having the address of the terminal device present as an element; a data buffer (86) for storing data to be transmitted to the LAN (31); Address filter (8
Control means (87) for instructing the data buffer (86) to write the data when notified from 5).

Common bus (7) is all LAN interfaces (61)
To (63), a data line (71) on which data output from the reception processing unit (82) is loaded in a time-division manner, and each LAN interface (6
1) to (63), a reference timing line (72) for supplying a reference timing for recognizing a time slot to which data is to be output by the reception processing unit (82), and data on the common bus (7) whose destination is unknown. And a broadcast control line (73) which becomes significant in some cases. Next, the operation of the above-described embodiment will be described using
The case where the terminal device (41a) connected to 1) communicates with the terminal device (42a) connected to the LAN (32) will be described. FIG. 3 shows the packet transmitted at this time. The start delimiter [SD] (91) is #BO.
Destination address [DA] (92) set in 4674, content is #
It consists of a source address [SA] (93) set in the OC4873, an information field [Info] (94) whose content is 0123456..., And a termination delimiter [ED] (95).

First, the terminal device (41a) transmits a packet on the LAN (31). Access control section of LAN interface (61) (8
1) sends a packet on the LAN (31) to its destination address (9
Regardless of 2), all are received and passed to the reception processing unit (82). The reception processing unit (82) reconstructs the packet according to the transmission speed of the common bus (7) by the data reconstructing means (83).

FIG. 4 shows the packet after reconfiguration. In FIG. 4, the hatched portion is invalid data. In parallel with the data reconstruction, the reception processing unit (82) transmits the reconstructed packet to the data line (7
Send to 1).

FIG. 5 shows the timing on the common bus (7). In FIG. 5, it is assumed that the LAN interface (61) is assigned the fourth to sixth time slots from the reference timing. This reference timing may be supplied by a device other than the LAN interface.
It is also possible for the interface to provide. Thus, by using the common bus (7) in a time-division manner,
Data delay in the reception processing unit (82) can be suppressed to a small value.

Next, the transmission processing unit (84) of the LAN interface (62)
Detects that a packet has appeared in a time slot allocated to another LAN interface, and determines whether the destination address is addressed to a terminal device in the LAN (32) or not.

Since the address # B04674 of the terminal device (42a) is registered, the address filter (85) notifies the control means (87) and the broadcast control line (73) of the registration. Control means (87)
Secures an area for one packet in the data buffer (86). Thereafter, the control means (87) writes the packet appearing on the data line (71) for each time slot into the data buffer (86) until the packet ends.

The transmission processing unit (84) notifies the access control unit (81) that there is a packet to be transmitted in the data buffer (86). Upon obtaining the right to access the LAN (32), the access control unit (81) requests transmission data from the transmission processing unit (84). The transmission processing unit (84) reads the packet from the data buffer (86) and passes the packet to the access control unit at the speed of the access control unit (81). The access control unit (81) transmits the packet to the LAN (32), and the bridge relay processing is completed. Finally, the terminal device (42a) receives the packet.

Since the time from when the packet appears on the common bus (7) to when the packet is written to the data buffer (86) is deterministic, the relay processing time together with the delay in the reception processing unit (82) is sufficiently accurate. Can be predicted.

Like the FDDI standardized by the American National Standards Institute (ANSI),
There is a LAN that provides a synchronous packet service, which guarantees packet transmission within a predetermined delay time. In order to provide this synchronous packet service in packet transmission via a bridge,
The relay processing time at the bridge must be deterministic.

However, as described above, a bridge suitable for the synchronous packet service can be obtained by using the common bus in a time-division manner.

On the other hand, the transmission processing unit (84) of the LAN interface (61)
Does not relay packets that appear in time slots 4-6 assigned to it. This is because a packet on the LAN (31) is transmitted to all terminal devices connected to the LAN (31) regardless of the bridge operation.

However, the address filter (85) of the LAN interface (61) notifies the broadcast control line (73) whether or not the destination address on the data line (71) is registered. further,
The address filter (85) checks whether the source address (# 0C4873 in this case) on the data line (71) is registered, and if not registered, registers it.

Also, the transmission processing unit (84) of the LAN interface (63)
Detects that a packet has appeared in time slot numbers 4 to 6 assigned to other LAN interfaces,
It is determined whether the destination address is addressed to a terminal device in the LAN (33) or not.

Address filter (85) for LAN interface (63)
Since the address # B04674 of the terminal device (42a) is not registered, the control unit (87) and the broadcast control line (73) are notified of the fact. The control means (87) does not write the packet into the data buffer (86).

If the address of the terminal device (42a) has not been registered in the address filter (85) of the LAN interface (62), the broadcast control line (73) does not receive a notification that the address has been registered from any LAN interface. This state is
It can be detected on the N interface. In this case, the LAN interfaces (62) and (63) both relay the packet.

When the response packet from the terminal device (42a) is received by the LAN interface (62), the address of the terminal device (42a) is registered in the address filter (85) of the LAN interface (62) as described above. As described above, a so-called address learning function can be realized by providing a broadcast control line.

Although not shown, the reception processing unit (82) also has a transmission processing unit (8
Like the case of 4), an address filter having an address table whose elements are the addresses of the terminal devices connected to the LANs (31) to (33) to which the self is connected is provided, and the LAN (31) to which the self is connected
(33) is not sent to the common bus (7), the amount of data on the common bus (7) is reduced accordingly. Even if the transmission speed and the operation speed of the transmission processing unit (84) are reduced,
A bridge having practically sufficient performance can be obtained.

Also, the reception processing unit (82) can access the address filter (85) so that the reception processing unit (82) can share a packet addressed to a terminal device connected to the LAN (31) to (33) to which the reception processing unit (82) is connected. If it is configured not to send to the bus (7), the same effect as above can be obtained with one address filter.

Although this embodiment shows a case where the common bus is used in time division multiplexing, it may be used in packet multiplexing by a bus access method as disclosed in, for example, Japanese Patent Application Laid-Open No. 58-48135.

As described above, according to the present invention, a plurality of communication network interfaces connected to a communication network and a common bus are provided, and the communication network interface includes an access control unit, a reception processing unit, and a transmission processing unit. The transmission processing unit is configured to include an address filter having a table having an address of a terminal device connected to the communication network as an element. Providing a communication network interface composed of the hardware described above has the effect that three or more LANs of the same speed can be interconnected to obtain a communication network connection device that is economical and has the flexibility of expansion. . Further, by using the common bus in a time-sharing manner, the time from when one data appears on the common bus to when reception ends can be determined.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system to which a communication network connection device according to one embodiment of the present invention is applied, and FIG.
FIG. 3 is a block diagram showing the configuration of the LAN interface, FIG. 3 is a packet diagram transmitted in the embodiment of the present invention, FIG.
FIG. 5 is a packet diagram after reconstructing the packet of FIG. 3, FIG. 5 is a timing diagram on a common bus, FIG. 6 is a block diagram of an entire system to which a conventional communication network connection device is applied, and FIG. It is a block diagram of the conventional communication network connection device. In the figure, (1) is a bridge (communication network connection device) (61) to (63) are LAN interfaces, (7) is a common bus, (31) to (33) are LANs, (41a) to (41n),
(42a) to (42n), (43a) to (43n) are terminal devices, (8
1) is an access control unit, (82) is a reception processing unit, (84) is a transmission processing unit, and (85) is an address filter. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A communication system for connecting a plurality of communication networks that perform communication by a packet having a destination address, receiving a packet transmitted on the communication network, determining a destination of the packet, and transmitting the packet to a target communication network. A network connection device comprising: a communication network interface individually connected to each of the plurality of communication networks; and a common bus interconnecting the communication network interfaces, and the communication network interface is connected to its own communication network. An access control unit for performing access control of the communication control unit; a reception processing unit for transmitting received data from the communication network obtained by the access control unit to the common bus; and a data addressed to the own communication network from the data on the common bus. Just choose A transmission processing unit for passing to the access control unit, the transmission processing unit includes an address filter having a table having an address of a terminal device connected to its own communication network as an element, and the internal bus in a time-division manner. A communication network connection device for transmitting data by using the transmission processing unit, wherein the transmission processing unit determines a data destination for a time slot assigned to a communication network interface other than its own communication network interface.