JPH03226141A - Local area network - Google Patents

Abstract

PURPOSE:To reconstitute a network quickly by reconstituting a network for an area in which either frame synchronizing signal or an idle pattern is received. CONSTITUTION:The network is provided with a frame synchronization detection circuit 10, a clock generating means 15, an idle pattern detection circuit 12 and an idle pattern generator 11 and its own station sends an idle pattern to a succeeding station when a frame circulating in the network is destroyed and no frame synchronization pattern is received. Then a station receiving the idle pattern relays the idle pattern to a succeeding station. Moreover, a station not receiving the frame synchronization pattern and the idle pattern recognizes occurrence of a line fault in the transmission line being the preceding area line and rebuilds the network in an area in which either the frame synchronization pattern or the idle pattern is able to be received. Thus, the network is quickly built up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a network in which stations are connected in a loop or ring.

(Prior Art) As shown in Fig. 3, in a LAN (Local Area Network) that connects stations 31 to 34 in a loop or ring configuration, disconnection of optical fibers, abnormality or deterioration of transmitting and receiving elements of optical repeaters, etc. When data errors occur frequently and line abnormalities occur, the frames circulating on the network are destroyed and communication becomes impossible.

The destination repeater performs regenerative relaying using a clock extracted from the received data, so if data is not sent from the previous station, the clock, which is a means of transmitting data to the next station, is lost, causing line abnormalities. Data cannot be sent to stations beyond the section where the loop or loop was rebuilt, leading to system failure.

As a method for detecting this transmission path abnormality, a conventionally used carrier disconnection detection method that monitors the deterioration of the timing component of an optical repeater may not be able to perform stable detection.

(Problem to be Solved by the Invention) As mentioned above, in the conventional LAN where stations are connected in a loop or ring configuration, only a specific station has the means to generate frames and clocks, so when a line abnormality occurs, In a system in which an optical repeater performs regenerative relay using a clock extracted from received data, if data cannot be received from the previous station, there is no clock as a means for transmitting data to the next station.

Therefore, data cannot be sent to stations after the section where the line abnormality has occurred, leading to system failure.

Furthermore, the conventionally used carrier disconnection detection method that monitors the timing component of an optical repeater has a problem in that stable detection of carrier disconnection alarms cannot be performed.

An object of the present invention is to provide a network that can be quickly reconfigured.

[Structure of the Invention] (Means for Solving the Problems) The present invention, which achieves the above-mentioned conventional objects, provides frame synchronization detection for each station to monitor the network in a network in which stations are connected in a loop or ring. The station is equipped with a circuit, a clock generation means, an idle pattern detection circuit, and an idle pattern generator, and when the frame circulating on the network is destroyed and the frame synchronization pattern is not received, the own station transmits the idle pattern to the next station, and the station transmits the idle pattern to the next station. The receiving station relays the idle pattern to the next station, and the station that does not receive either the frame synchronization pattern or the idle pattern recognizes that a line abnormality has occurred in the transmission path in the previous section, and relays either the frame synchronization pattern or the idle pattern. The feature is that the network is rebuilt in the section where it is possible to receive the same message.

(Function) In the present invention, when frames circulating in the network are destroyed and no frame synchronization pattern is received, the own station transmits an idle pattern to the next station, and the station that has received the idle pattern transmits the idle pattern to the next station. A station that relays and does not receive either a frame synchronization pattern or an idle pattern recognizes that a line abnormality has occurred in the transmission path in the previous section, and rebuilds the network in the section where it can receive either the frame synchronization or idle pattern. do.

Therefore, since idle patterns or frames are constantly circulating on the network and the line never runs out of carriers, it is not necessary to restart the optical repeater, and a network connecting stations in a loop or ring can be quickly restarted. be able to configure.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a station in a local area network according to an embodiment of the present invention.

In the present invention, frames are circulated through each line (P-system optical transmission line, S-system optical transmission line) of the network shown in FIG. 3. Furthermore, an index indicating a transmission path through which communication is currently being carried out between stations is inserted into each frame.

In FIG. 1, each station includes an optical repeater 1.
2, a frame synchronization detection circuit 10 for detecting a frame synchronization pattern, and an idle circuit as a means of not losing carriers on the network (allowing downstream stations to extract the clock) when the frame synchronization pattern disappears. An idle pattern generator 11 that generates a pattern (in this embodiment, for example, 101010101
0...) and an idle pattern detection circuit 12 that detects an idle pattern.
A selector 13 is installed to select the clock and data.

The 7L/- frame synchronization detection circuit 10 is a circuit for identifying a frame synchronization pattern (a pattern that does not appear in subsequent data). Synchronization protection is applied so that it is not determined that the frame is synchronized, and that it is not determined that the frame is out of synchronization unless the frame is destroyed twice in a row and the out-of-frame synchronization is received twice.

The idle pattern generator 11 also includes an FF (flip-flop) (not shown) that divides the frequency of the clock from the clock oscillator of the station, and a clock oscillator 15.
It is constituted by a frequency divider circuit 16 which thereby generates an idle pattern.

In addition, the idle pattern detection circuit 12 also uses the optical repeater 1.
The received data and clock are input to the shift register 17, and the data output (
EX-OR (exclusive OR) is performed on DO and D4, Dl and D5, etc.). Then, EX-OR output (CO and C4
, C1 and C5...), an idle pattern is detected and it is determined that there is a carrier on the transmission path.

The selector 13 selects whether to use the data from the idle pattern generator 11 of each station as the transmission data, to use the received data as is (idle pattern or frame relaying), or to transmit a frame. The selection is made by decoding the frame synchronization and idle pattern detection outputs.

FIG. 2 shows a circuit diagram of the selector 13.

The operation will be explained below.

When frame synchronization is established by the frame synchronization detection circuit 10, the frame is relayed to the next station under the control of the controller. Furthermore, when frame synchronization is lost and an idle pattern is detected, the received idle pattern and reception clock are relayed as they are to the next station and transmitted to the next station. Furthermore, if frame synchronization is lost and no idle pattern is detected, the clock of the own station's clock oscillator and the idle pattern generated thereby are transmitted to the next station.

When setting up the network or executing loop control, take into account the time required for the optical repeater to stabilize, and set the WAI
The frame received by the T signal is relayed as is.

Since idle patterns or frames are constantly circulating on the network, the line never runs out of carriers. Therefore, there is no need to re-excite (re-start) the AGC of the optical repeater receiving section (0/E section), so the software that reconfigures the line of each station checks the line monitor every 3 frames (125 μsec) or so. It is possible to sample and initiate line reconfiguration.

This allows for rapid loop or ring reconfiguration.

[Effects of the Invention] As explained above, according to the present invention, a carrier is always present on the line, so there is no need to restart the optical repeater, and a network in which stations are connected in a loop or ring can be quickly constructed. It can be reconfigured into

Furthermore, since the line monitoring function directly monitors data bits, it is a highly reliable line abnormality detection method.

[Brief explanation of drawings]

FIG. 1 is a diagram of a station line monitor circuit showing the principle of the present invention, FIG. 2 is a circuit diagram of a selector, and FIG. 3 is a configuration diagram of a network in which stations are connected in a loop or ring. 1.2... Optical repeater, 10... Frame synchronization detection circuit, 11... Idle pattern generator, 12...
Idle pattern detection circuit, 13...Selector, 15
... Clock oscillator, 16... Frequency divider circuit, 31-3
4...Station.

Claims (1)

[Claims] In a network in which stations are connected in a loop or ring, each station is provided with a frame synchronization detection circuit, an idle pattern detection circuit, a clock generation means, and an idle pattern generator for monitoring the network. When the circulating frame is destroyed and no frame synchronization pattern is received, the own station transmits an idle pattern to the next station, and the station that receives the idle pattern relays the idle pattern to the next station, and transmits the frame synchronization pattern or idle pattern. A local area network characterized in that a station that does not receive any of the above recognizes that a line abnormality has occurred in the transmission line in the previous section, and reconstructs the network in a section where either the frame synchronization or the idle pattern can be received. .