JPH0342739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a local area network using a digital communication method, and in particular, a plurality of node stations are connected through a loop-shaped transmission path, and this common transmission path is a high-speed, large-capacity network. Concerning scale loop type local network system.

[Prior art]

Conventional local networks (hereinafter referred to as LANs) are bus-type LANs that connect devices in a narrow, limited area, or small-scale loop-type LANs with a number of M ~
The mainstream was a medium-scale LAN of about 10 Mb/s, or a medium-sized LAN of about 10 Mb/s to 32 Mb/s using optical fiber cables.

However, in recent years, advances in optical technology have made it possible to create loop-type transmission lines using optical fibers with transmission speeds of 100 Mb/s to several hundred Mb/s. We are trying to build an integrated large-scale loop LAN that will serve as a trunk network.

However, even if the transmission path becomes faster and has a larger capacity, there are limits to the processing capacity of the packet switching device of each node station and the operating speed of the circuit elements that make up the loop access control section. Therefore, it is not technically or economically advisable to increase the hardware size of each node station or to use high-speed elements in a wide range of circuits in response to the high speed and large capacity of the transmission line.

[Purpose of the invention]

The present invention provides an economical and expandable system in which each node station connected to a high-speed, large-capacity loop transmission line can handle increased speed and capacity by assembling a minimum number of high-speed logic circuit elements and a conventional hardware configuration. It provides a loop-type LAN with

[Structure of the invention]

In the present invention, a plurality of node stations equipped with a packet switching device or a packet switching device and a circuit switching device are coupled to a loop-shaped digital transmission path, and packet-switched data communication and circuit communication are performed via this common transmission path. In a loop-type LAN that transmits exchanged data communication in a time-division manner,
The time division multiplexed loop transmission path is divided into a specific number of time slot groups, and the packet switching device of the node station has means configured by combining packet switching modules that can access only an arbitrary time slot group, and a plurality of time slot groups on the loop transmission path. This system is characterized by being equipped with a node station that has the function of exchanging packet data between time slot groups.

[Explanation of Examples]

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

First, FIG. 1 is a diagram showing the configuration of a conventional loop-type LAN (local area network). In the figure, node stations 3 and 4, which are remote stations, are connected by an optical loop transmission line LP.
has a line switching device 20 and a packet switching device 10, and a node station 2, which is a central station, has a loop synchronization circuit, a system failure monitoring function, and the like.

FIG. 2 shows a block diagram of the node stations 3 and 4, which are the remote stations in FIG.
A packet switching device 10 includes a loop access control circuit 30 including a loop multiplexer 33, a transfer control circuit 11, a microprocessor circuit 13, an internal bus 12 connecting these, and the like.
and Note that the line switching device 20 connected to the loop multiplexer 33 is omitted from FIG. 2.

Here, the loop transfer speed of the loop-type LAN shown in Figure 1 is a small to medium-sized LAN of several Mbps to several tens of Mbps.
In this case, the transfer control circuit 11 of the packet switching device 10 in FIG.
Operation and processing at that parallel signal speed is possible, but each node station must check whether the packet switching data (packet frame) on the loop LP is addressed to its own node station or not. After checking, if the packet frame is addressed to another node station, the packet frame that has arrived at the receiving circuit must be immediately transferred from the transmitting side to the next node station downstream of the loop LP.

That is, the transfer control circuit 11 of the packet switching device 10 is a circuit that has to handle the data contents on the loop LP in real time.

Therefore, the loop transmission line LP has a speed of 100 to several hundred Mbps.
In a high-speed, large-capacity loop type LAN having a transfer rate of 1, the logic circuit elements constituting the transfer control circuit 11 of the packet switching device 10 are required to be element components that operate at high speed. Furthermore, as the data transfer capacity of the loop LP increases, the processing capacity of the packet switching device 10 is also required to be large.
However, node stations 3 and 4 of each remote station
It is not appropriate to increase the scale of all hardware in the system. Therefore, the present invention provides high-speed, large-capacity
An example in a LAN is shown in FIG.

Node station 3 of the remote station in Figure 3
The packet switching function possessed by N, 4N is composed of two packet switching modules 10N.

Here, the data frame of the high-speed optical loop transmission line LP that is time-division multiplexed is as shown in Fig. 5.
For example, time slots (TS ₁ , TS ₂ , TS ₃ )
The time slot (TS 1 ) is divided into three slots, and the time slot (TS ₁ ) is used as a circuit-switched data transfer channel (CS).
Also, time slots (TS ₂ and TS ₃ ) are assigned as data transfer channels (PS) for packet exchange. Note that the superframe in FIG. 5 indicates a specific frame length determined by the basic data rate accommodated in the circuit-switched data transfer channel (CS).

Then, the time slots (TS ₂ and TS ₃ ) assigned as this packet channel (PS) are further separated into two packet channels, and a packet switching group is created that uses only the time slot (TS ₂ ). and a packet switching group that similarly uses only the (TS ₃ ) slot.

Here, the two packet switching modules 10
N as a group of packet switches (PS ₁ ) each using a time slot (TS ₂ ) as a transport channel;
A time slot (TS ₃ ) is configured into a packet switching group (PS ₂ ) to be used as a transport channel.

This allows individual packet switching modules 10
N can reduce the circuit operation and processing speed because the packet channel transfer rate on the loop LP is halved by dividing into two.

Furthermore, the packet-based terminals accommodated in the packet switching group (PS ₁ ) and the packet switching group (PS ₂ )
Because _{it is} necessary to enable communication with packet _- type terminals accommodated in A packet having a function of transferring the packet data to the transfer channel (TS ₃ ) of the group (PS ₂ ), and also having a function of transferring the packet data from the group (PS ₂ ) to the transfer channel (TS ₂ ) of the group (PS ₁ ). A node station 5 having a system time slot conversion device (PTSS) is added to the loop LP.

FIG. 4 is a configuration diagram based on a spatial division representation of FIG. 3, and is drawn to assist in understanding the configuration of FIG. 3.

The loop LP in Fig. 4 has a time slot (TS ₁ ,
TS ₂ , and TS ₃ ), and the line switching equipment 20 of each node station 3N, 4N is divided into three groups.
N, packet switching modules 10N of the packet switching group (PS ₁ and PS ₂ ) are connected. An embodiment of the packet-based time slot converter (PTSS) of the node station 5 is shown in FIGS. 6B and 6C.

Next, the configuration and operation of FIG. 6C will be explained. A circuit 51 for receiving a packet data frame from the channel of the time slot (TS ₂ ), a receiving circuit 51
If the destination of the packet is the packet switching module 10N belonging to the channel (TS ₃ ), then
Buffer queue 5 of the receiving side data that holds the data in order to send it to the channel loop side of TS ₃
3, and if the received data is data destined for its own channel loop system (TS ₂ ), it is immediately sent to the transmitting circuit 5.
Sent from 2. Note that 54 is a selection circuit.

The data held in the reception/transmission data buffer queue 53 is sent out from the transmission circuit 52M via the selection circuit 54M after the reception circuit 51M acquires the transmission right of the transmission destination channel loop (TS ₃ ). .

Conversion from a TS ₃ channel loop to a TS ₂ channel loop is performed in a similar manner.

As described above, according to the method of the present invention, a high-speed, large-capacity loop-type LAN is realized using the packet switching module 10N with conventional speed and processing capacity.

〔Effect of the invention〕

As explained above, each node station connected to the transmission path of a high-speed, large-capacity loop is assembled with a minimum number of high-speed logic circuit elements and conventional-scale hardware configuration modules, thereby increasing the speed and capacity of each node station. Since the system can be used in local area networks, it is effective in realizing a local area network that is easy to design, economical, and flexible in expansion.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional loop-type local area network, FIG. 2 is a block diagram of a remote station in FIG. 1, and FIG. 3 is a block diagram of a high-speed, large-capacity loop-type local area network according to the present invention. FIG. 4 is a diagram showing an example of the workpiece, and FIG.
This figure is a configuration diagram of a multiplexed frame of the loop in FIG. 3, and FIG. 6 is an example of a configuration diagram of each main part of the same embodiment. LP: loop (transmission line), 2: central node station, 3, 4, 3N, 4N: remote node station, 10: packet switching device, 10N: packet switching module.

Claims (1)

[Claims] 1. A loop in which a plurality of node stations each equipped with at least a packet switching device are coupled to a loop-shaped transmission path, and data communication by packet switching is transmitted in a time-sharing manner via the transmission path. In a type of local area network, a time-division multiplexed loop transmission path is divided into a specific number of time slot groups, and a packet switching device at the node station installs a packet switching module that can be accessed only by any given time slot group. A time slot exchanging node station configured by combining a plurality of time slots and exchanging packet data between the arbitrary time slot groups on the loop transmission path is provided, and the packet exchanging module of the plurality of node stations is provided in one time slot group. packet switching modules that are assigned the same time slot group use this time slot group to directly transmit data, and between packet switching modules that are assigned different time slot groups, the time slots are exchanged. A loop-type local area network system characterized in that data transmission is performed by exchanging packet data between the different time slot groups via a node station.