JPH03280734A - Loopback transmission controller - Google Patents

Abstract

PURPOSE:To facilitate remote loopback by providing a code representing two kinds of states to identify the loopback mode and the conventional on-line mode to a pseudo silence signal in a frame. CONSTITUTION:An optical reception section 21 receives an optical signal k1, sends a signal to a pseudo silence detection section 23, which detects whether the signal represents the loopback mode or the conventional on-line mode and outputs the identified result to a loopback control section 24. The control section 24 outputs a signal (f) being logical 1 in the case of the loopback mode and being logical 0 in the case of the conventional on-line mode. An optical transmission signal selection section 27 selects a test frame being the output of a clock extraction.re-clocking signal 22 when the output (f) of the control section 24 is logical 1 and applies loopback transmission to the system. Then the loopback signal is sent via an optical transmission section 28 as an optical signal k2 and a selection 27 of other station relay section is reset. Thus, the loopback is easily implemented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a loopback transmission control device, and more particularly to a loopback transmission control device in a relay system (LAN) using an active star.

[Prior Art] FIG. 5 is a block diagram showing an example of a LAN (Local Area Network) using a conventional active star. In the figure, 1 is an active star, and 2 is a plurality of (n) stations connected to the active star 1. The active star 1 and the plurality of stations 2 are connected in a star shape as shown in the figure. In the example shown in the figure, data transmission is performed bit-serially using light. Corresponding to the number of stations 2, the active star 1 includes a station relay section 1a.
is provided. Then, the office relay section 1a is connected to the bus 1b.
and 1c.

In the system configured in this way, each station 2 has the following rights in order to transmit information to other stations, to transfer bus usage rights to other stations, etc.
A frame with a preamble (fixed pattern for training such as receiver bit clock extraction) is transmitted in bursts to active star 1, and active star 1 receives this and transmits it to all stations 2 via active relay section 1a. Relay. Here, the optical signal IC from the station 2 to the active relay section 1a-□\
1 and 2 for the optical signal from the active relay section 1a to the station 2 are used in the coaxial gear relay band of IEEE 802.4, for example, FSK ("0
''' or a square wave with a period of 1/'2 of the bit period, "1-"
(or a square wave with the same period as the bit period, and there are always transitions at the boundaries and in the middle of the bits).

For the sinion state between the hoop and the frame, it is common to use a pseudo sinionce created by a slower square wave that does not appear in the signal pattern inside the hoop. The purpose of pseudo-silence is to perform automatic tuning of the optical receiver (automatic conversion of the on/off amplitude of the optical signal into binary values of 0 and 1 by setting a certain threshold) even when there is no j-nome transmission. (threshold value control, etc.).

Akudipster 1 is a flap L with a preamplifier.
When a clock signal is received from one of the stations 2, it is re-clocked (waveform-shaped into a jitter-free clock) using the extraction V1 check and relayed to other stations. / in the state where only the
Pseudo-silence is sent back to all stations 2 to indicate that all stations are free.

FIG. 6 is a diagram showing the frame format.

One unit of the frame is the preamble as shown in the figure.
〇, Start delimiter 11. Frame controller 1-o-rule 12, which performs control such as instructing to enter remote loopback state; Address 13, which indicates the address of the oscillator station of the frame, j of the station to which the frame is transferred.
'Destination address 14, which does not indicate the address, and data section 15, which is a set of data to be transferred. Frame 1, no sequence, FC816 and EnI delimiter 1
Consists of 7. - Both ends of the moon gnome are sandwiched by the aforementioned (7) pseudo-Xirens.

[Invention or Solution 1 - Problem to be Solved] Evaluate the failure location using i-A N as shown in Fig. 5.
), it is done as follows. That is, specific station 2
The death door 1 norm is sent to the active star 1 from , the test) I norm returned from the active star 1 is received 17 and checked for comparison with the sent test frame. As a result of the comparison, if a mismatch occurs [2j-], it means that Rn exists in the transmission system including the optical signal transmission line 1 interface, and it is necessary to isolate the faulty point.

During the above-mentioned remote loopback transmission (7), active star 1 performs a
The first station connected to the remote control will be taken offline and kept there.

In addition, if a station has detected an abnormality in a remote loopback test, it is necessary to keep it in an offline state (-1).In conventional systems, there is no intelligence function that easily performs loopback transmission control. was not added, and complex control was performed.

The present invention has been made in view of these problems, and its purpose is to provide a return transmission control device that can easily perform remote loopback.

"Means for Solving the Problems" The present invention for solving the above-mentioned 1.f problem is an active star LAN system in which a plurality of stations and relay units provided corresponding to these stations are connected in a star shape. , two modes are provided for the pseudo-silence signal inserted between frames, a normal mode and a return transmission mode,
A pseudo-silence detection section is installed in each relay section to detect whether the pseudo-silence signal sent from the station is in mode 1, and if the detected pseudo-silence signal is in loop 1 to transmission mode. is characterized in that the active star is connected only to the station that sent the pseudo-signal, and is offline from other stations.

[Operation] Two types of pseudo-silence are provided in the frame sent from the station to the active star, indicating loopback designation or online (normal mode) designation. This allows the station repeater in the active star that receives frames from the station to easily identify the type of pseudo-silence, and in the case of remote loopback, sets all other stations offline. be able to.

[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 an embodiment of a relay section for each station of an active star according to the present invention, and FIG. 2 is a block diagram showing an embodiment of a relay section for each station according to the present invention. The entire system of the device of the present invention is similar to the LAN system shown in FIG.

Components that are the same as those in FIG. 5 are designated by the same reference numerals.

First, the relay section for each station will be explained.

In FIG. 1, reference numeral 21 denotes an optical receiver that receives 1 in the optical signal from the station, and converts the optical signal kl (on/off binary code) into an electrical signal. Generally has an automatic threshold control function,
If the optical signal level is above the specified level (“1”) or not (0) is output as a signal. Among the signals output from the optical receiver 21, the a signal is an optical signal and 1 is an electrical signal. The converted signal b indicates whether the optical signal contains 1 or more than a specified level.

22 is a clock extraction/re-clocking unit which extracts a clock from the pseudo-silence pattern of the signal a and the FSK signal of the frame part (using, for example, PLL, etc.), re-clocks the signal a with this clock, and generates the signal C. shall be. Reference numeral 23 denotes a pseudo-silence detection section that receives the a signal and b signal output from the optical receiver 21 and detects pseudo-silence.

The pseudo-silence used in the present invention is of the following two types.

■Pseudo-silence 1: Also serves as control to bring the relay section for each station of Active Star offline (loopback mode) ■Pseudo silence 2: Also serves as control to bring the relay section for each station of Active Star online (normal mode) The pseudo-silence detection unit 23 detects that the received signal is the pseudo-silence 1. It detects whether it is pseudo-silence 2 and outputs the result as a signal d indicating whether it is a frame reception state (“1”) or a silence reception state (“0”).

24 learns from the signal group e from the pseudo silence detection unit 23 whether pseudo silence 1 or 2 is being received;
Decide whether to loopback or online,
This is a loopback control unit that outputs this determination as a signal f. This signal f outputs "1" during loopback and "0" when online.

25 is a bus signal 2 driver that receives signals d and f, and when signal f indicates an online state and signal d indicates a frame reception state, it outputs bus signal 2 as "1" and relays it to the relay section for other stations. instruct.

Under other conditions, "0" is output. 26 is signal c,
Bus signal 1 driver that receives d and f, bus signal 2 or "
When bus signal 2 outputs "1", signal C is output as bus signal 1. When bus signal 2 does not output "1", this driver 26 is turned off.

27 is the signal bus signal 1. An optical transmission signal selection section receiving bus signal 2 and signal f selects a signal to be output as signal g to optical transmission section 28 according to the states of these received signals. The selection will be as shown in FIG.

28 is an optical transmitter that receives the signal g from the optical transmission signal selection g527, converts it into an optical signal, and outputs it as an optical signal 2.

Here, the bus signal 1 outputs "1" when any relay section receives a frame with a preamble from a corresponding station as an optical signal of "1". This bus signal 1 uses a wired-OR system, and if any relay section is set to "1"
If it outputs "1", it becomes "1", and if neither relay section outputs "1", it becomes "0". Further, this bus signal 1 is also a signal for requesting another relay section to relay the optical signal to 2 via bus signal 2.

For bus signal 2, while receiving a frame from a corresponding station (optical signal kl), one of the relay units reclocks the received FSKi signal using the extracted clock and outputs the waveform along with the output of bus signals 1 to 1. . The relay section that is not driving the bus signal 1 and the bus signal 2 receives the bus signal 1-1 and relays and outputs the FSK signal of the bus signal 2 as the optical signal riff 2. The operation of the circuit configured as described above must be explained as follows.

The optical receiver 21 receives an optical signal 1 from the station, converts it into an electrical signal 12, signals a, l], and outputs the signal.

The pseudo-silence detection unit 23 receives input 1 from the signals a and b.
It is detected whether the xirence signal obtained by -1 is a pseudo xirence signal or -12. The detection results are sent to the loopback control unit 24 as signal groups e and 1. is output.

The loopback control unit 24 receives the signal group e and determines whether to enter the loopback or online state 1-
1 This decision is output as signals f and l~.

This signal f becomes "1" during loopback control and "0" during online state. The bus signal 2 driver 25 sets the bus signal 2 to "1-" when the signal f is "0" indicating online, or when the output d of the pseudo-sign 1 nonce detector 23 indicates the frame receiving state, and the other Instruct the station relay unit (same configuration as in Figure 1) to relay.Bus signal 2
The driver 25 outputs "0" for conditions other than "-2". bus signal], the driver 26 operates the clock extraction/reclocking unit 2 only when the bus signal 2 is “1.”
Outputs the output C of 2. As a result, the LA shown in FIG.
N are connected online, and de-re()lnorm) transfer is performed between stations 2 via active star 1.

When the output f of the loopback control unit 24 is “1”, that is, when the loopback is instructed, the optical transmission signal selection unit 27 selects the test “no 1 norm” which is the output of the clock extraction/reclocking unit 22. Select [7] and send.

This return signal g is converted into an optical signal by the optical transmitter 28.
and 1. 17 is sent back to the originating station. In this loopback mode, the optical transmission signal selection section 27 of the other relay section is turned off, so that it is not influenced by the system that is connected one-to-one with the active star.

Next, each station in FIG. 2 will be explained. In the figure, 3
1 converts the signal l] from the FSKS side modulation 3 into an optical signal, 1
An optical transmitter 32 converts the optical signal 2 from the active star into an electrical signal i and transmits it to the active star. Applicable.

The optical receiver 32 has an automatic threshold control function (-), and has a carrier detector (not shown) that outputs a signal j indicating whether the received optical signal level is equal to or higher than a specified level. These signals +3'L and j enter demodulation 4 on the FSKS side.

The FSKS side modulator 3 receives the signal group k from the media access control unit 35, performs FSK modulation on it, and generates a signal. The FSKS side demodulator 4 receives the signal i and the carrier detection signal j from the optical receiver 32 and outputs it as a demodulated signal Ω. Carrier signal J or optical signal shows 1 novel drop 1. If the media access control unit 3
5.

Reference numeral 35 denotes a media access control unit which performs 1-Kumbus control, frame generation/decoding control, etc., and realizes necessary transmission of the second layer 36 (communication control). FSKS side modulation 3. It interfaces with the demodulator 34 through signal groups k and Q. The signal pk is bit information that the media access control unit 35 outputs to the FSKS side modulation 3 for transmission,
It consists of "0", "1-", "silence (non-sending)", PIT/timing clock, locks required for modulation, and "lubeback silence".
The FSKS side modulation 3 modulates the "nonce" and "lube hack silence" so that they correspond to the pseudo silence 1/res 1/2 to the optical signal, respectively.

Signal group g is bit information sent from the FSKS side demodulator 4 to the media access control unit 35, and includes "O", "1-", "Signal nonce (pseudo)", "9", "Signal 1 novel drop", "B
It consists of a bit timing clock such as "AD (encoding rule violation)" and a "loop back silence".The conventional 'silence' and 'loop pack silence' correspond to the signal i and the optical signal 2, respectively. The FSX demodulator 34 demodulates the signal so as to make the signal.

Further, the media access control unit 35 performs transmission/reception as a service to the loopback control unit 38 or transmits/receives it as a service to the communication control upper layer 36 according to instructions from the loopback control unit 38 (described later). Decide whether to receive data.

In addition, pseudo-silence 1 when performing transmission/reception as a service to the loopback control unit 38. The selection of pseudo-silence 2 follows instructions from the loopback control section 38.

36 is a communication control layer, so-called ISO 03I (Op.
n System Interconnection
n) Consists of a logical link control layer to an application layer in a 7-layer hierarchy.

Reference numeral 37 is an application that performs communication usage for the user. 38 is a loopback control section connected to the media access control section 35, which is a feature of the present invention.

Next, the signal group m connecting between the media access control section 35 and the loop check control section 38 will be explained. This signal group m is a signal including the following contents.

■The media access control unit 35 is the loopback control unit 3
A signal from the loopback control unit 38 that instructs whether the service should be provided to the communication control upper layer 36 or the communication control upper layer 36.The loopback control unit 38 instructs whether to output pseudo silence 1 or pseudo silence 2 as the silence signal. - A signal from the media access control unit 35 indicating whether pseudo-silence 1 or pseudo-silence 2 has been received as a signal from the active star. - The media access control unit 35 receives the signal from the loopback control unit 3.
The operation of the circuit configured as described above is as follows.

At power-up, when the media access control unit 35 detects a serious transmission error, the control authority of the media access control unit 35 is transferred from the communication control upper layer 36 to the loopback control unit 38 as necessary, and the signal Instruct group k to output pseudo-silence 2 (loopback instruction).

When it is confirmed through the media access control unit 35 that pseudo silence 2 is received in the optical signal 2 (loopback state has been entered) while instructing the active star to loop back. It instructs the media access control section 35 to transmit the test frame, loops back, receives the received test frame from the media access control section 35, and checks the comparison with the transmitted test frame.

In the loopback transmission test, if there is no abnormality and the active star is to be released from the loopback state, the loopback control unit 38 instructs the media access control unit 35 to output pseudo silence 1. When it is confirmed through the media access control unit 35 that pseudo-silence 1 has been received from the optical signal 2 (online state has been established), the loopback control unit 38 grants communication control rights to the media access control unit 35. return.

FIG. 4 is a diagram showing an example of a transmission signal according to the present invention.

(a) shows the operation during remote loopback, and (b) shows the operation during normal mode (online). In (a), QS1 indicates the pattern of pseudo-silence 1, and in (b), QS2 indicates the pattern of pseudo-silence 2. Both are low frequency signals that are not affected by frames. In the example shown, QS
2 has a slightly higher frequency than QSl.

In the above description, an example is given in which the FSK modulation/demodulation method is used as the data modulation/demodulation method, but the present invention is not limited to this, and other modulation/demodulation methods can be used. Signal transmission also does not need to be an optical signal;
It may be a normal electrical signal.

[Effects of the Invention] As described above in detail from 1 to 1, according to the present invention, a pseudo silence signal inserted between a frame and a frame is
By providing two types for distinguishing between the loopback mode 1 and the current online mode, it is possible to provide a return 1-7 transmission control device that can easily perform remote loopback.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the relay section for each part of an active star according to the present invention, FIG. 2 is a block diagram showing an embodiment of the structure of each station according to the present invention, and FIG. 3 is an optical transmission signal. FIG. 4 is a diagram showing an example of a transmission signal according to the present invention; FIG. S5 is a block diagram showing an example of a LAN using a conventional active star; FIG. FIG. 1 shows an example of a frame format. 21 Optical receiving section 22... Clock extraction/re-clocking section 23... Pseudo size 1 nonce detection section 24... Loopback control section 25... Bus signal 2 driver 26... Bus signal 1 driver 27... Optical transmission section code selection section 28...Optical transmission section 31...Optical transmission section 32...Optical reception section 33...FSK modulation section 34...FSK demodulation section 35...Media access control section 36...・Communication control upper layer 37...Application cage 338...Loopback control section

Claims (1)

[Claims] In an active star LAN system in which multiple stations and relay units corresponding to these stations are connected in a star configuration, two modes are available for the pseudo-silence signal inserted between frames: normal mode and return transmission mode. A pseudo-silence detection section is installed in each relay section to detect which mode the pseudo-silence signal sent from the station is in. If the detected pseudo-silence signal is in return transmission mode, the active star is a return transmission control device configured to connect only to the station that sent the pseudo-silence signal and to be offline from other stations.