JPH01288134A - Changeover system for master equipment and sub-master equipment of loop lan - Google Patents

Abstract

PURPOSE:To attain changeover from a master equipment to a sub-master equipment even in the interruption of an external clock by sending changeover information of the master equipment and the sub-master equipment in addition to the information representing the reception state of an external clock newly as well as the state of the master equipment as the changeover information of the master equipment and the sub-master equipment. CONSTITUTION:The sub-master equipment 2 inserts '1' to an external clock frame during the reception of an external clock and inserts '0' when a reception clock is interrupted. Thus, if the external clock to its own station is interrupted, the master equipment 1 discriminates the state of the sub-master equipment 2 by the external clock reception frame and remains the bit of a master function sub-master function switching control frame to '0' in the presence of the external clock of the sub-master equipment 2 thereby switching the function between the master equipment 1 and the sub-master equipment 2 and is operated by the clock of the master equipment 1 while independent synchronization is applied to the loop even if the external clock supply to the sub-master equipment 2 is interrupted simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to switching between a loop-type LAN master device and a sub-master device, and particularly to a loop-type LAN master device capable of receiving an external clock.

This invention relates to a submaster device switching method.

[Conventional technology]

Conventionally, it has a master device and a sub-master device.

In a loop type LAN capable of receiving an external clock, switching from a master station to a submaster station is performed only when a failure occurs in the master device.

[Problem to be solved by the invention]

The above-mentioned conventional loop type LAN master device.

When switching sub-master devices, the switching operation is performed only when the master device fails, so if the external clock to the master device is cut off while the LAN system is operating by receiving an external clock, the master device will be switched off unless there is a failure in the master device. As a result, the switching operation from the device to the submaster device is not performed.

There is a problem in that reception with external networks is no longer possible.

[Means to solve the problem]

According to the present invention, in a loop optical LAN having an external clock receiving function and including a master device and a submaster device, first means for monitoring and transmitting the external clock reception state of the master device and the submaster device; , a second means for switching a synchronization/monitoring system from the master device to the sub-master device when an external clock to the master device is cut off.
A submaster device switching method is obtained.

[Effect]

The loop-type LAN master device/submaster device switching method of the present invention adds and transmits not only the state of the master device but also information indicating the receiving state of the external clock as switching information of the master device and submaster device. Switching from the master device to the sub-master device also occurs due to clock interruption.

〔Example〕

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

FIG. 1 is an overall configuration diagram of a loop type LAN system to which the present invention is applied. Referring to FIG.

1 is a master device that manages synchronization control within the loop and has an external clock reception function for connection with a digital synchronous network; 2 is a master device that controls the synchronization control within the loop; and 2, the master device 1
It is a submaster device that performs the functions of master device 1.
One sub-master device 2 and one sub-master device 2 are installed in each loop. Reference numeral 3 denotes a terminal station device capable of accommodating various interface boards. A plurality of terminal station devices are installed in a loop, and various terminal devices (not shown) can be connected thereto. Reference numeral 10 denotes an optical fiber cable containing at least two optical fibers, and connects the front terminals 3 of each terminal station. 20 is a device for supplying a clock from the digital network to the loop in order to connect the digital synchronous network and the LAN;
and 40 are clock supply cables for supplying the clock to the loop.

FIG. 2 shows the data frame format transmitted within the loop. ] 000 is the entire data transmission frame + 1000a master function submaster function switching control frame (MSW), 1000b external Otsuk7
v-mu (EXT CLOCK), 1000c
It consists of a data frame (DATA) of 1000d and a control and synchronization frame (SV-8YN) of 1000d.

When a loop type LAN operates by receiving an external clock, the master device 1. The sub-master device 2 receives a synchronization clock from an external digital synchronization network via the clock supply device 2, and the clock of the master device 1 is slave-synchronized to the clock, and the loop operates.

In addition, switching between the master device and submaster device in the loop is performed using the master function submaster function switching control frame in the data frame format l-(1000).
This is done by inserting 11" and converting it to O" in submaster device 2. Submaster device 2 monitors this switching control frame, and when it arrives at its own station, this switching control frame is "1". If it is "0", it is converted to "0", and if it is "0", the submaster function is activated to control master device 1.
Switching from the submaster device 2 to the submaster device 2 is performed. Furthermore, submaster device 2 inserts 91' into the external clock frame (1000b) while its own station is receiving the external clock, and inserts "O" when the receiving clock is cut off.By doing this, master device 1 Now submaster device 2
It is possible to know whether or not the device is receiving the clock.

By the way, conventionally, if the external clock to the master device is cut off, the loop cannot be independently synchronized.

In the present invention, the master device 1 determines the status of the submaster device 2 when the external clock to its own station is cut off based on the external clock reception frame. However, if there is an external clock for the submaster device 2, leave the bit in the master function submaster function switching control frame as "0".

Master device 1. The functions between the submaster devices 2 can be switched, and if the external clock supply to the submaster device 2 is also cut off at the same time, the loop can operate with the clock of the master device 1 as an independent synchronization. .

In this way, by knowing the clock reception state of the submaster device 2, the master device 1 can switch between the master device and the submaster device not only when there is a failure in its own station, but also whether there is an external clock or not.

〔Effect of the invention〕

As described above, in the present invention, the submaster device transmits the reception state of the external clock to the master device, so that switching to the submaster device is performed when the external clock is disconnected from the master device. As a result, the submaster device can synchronize with the external network, and even if the clock supply from the external clock supply device to the master device is cut off, communication with the external network is possible.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a transmission frame format within a loop type LAN. 1...Master device, 2...Submaster device, 3...
・Terminal equipment, 10... Optical fiber cable, 20...
- Clock supply device, 30...external clock supply cable. 40...External clock supply cable, 1000...
...Data transmission frame, 1000a...Master function/submaster function switching control frame (MSW),
1000b...External clock frame (EXT
CLOCK), 1000c...Data frame (DATA), 1000d...Control and synchronization frame (SV-8YN). Figure 2 too.

Claims (1)

[Claims] 1. In a loop optical LAN having an external clock receiving function and including a master device and a submaster device, a first means for monitoring and transmitting the external clock reception state of the master device and the submaster device, and a first means for monitoring and transmitting the external clock reception state of the master device and the submaster device, and second means for switching a synchronization/monitoring system from the master device to the submaster device when a clock is cut off.