JPH07183906A - Self-recovery ring network system - Google Patents

Abstract

PURPOSE:To perform path switching fast at each node of the self-recovery ring network in case of signal deterioration of an STS1 level. CONSTITUTION:If a signal deterioration detection part 10 detects signal deterioration at a through node D, a VT AIS insertion part 22 inserts alarm information into a VT AIS frame under the control of a control part 21. At a next-stage node A, a VT AIS detection part detects this alarm information and a selector 14 switches the path from a CCW direction to a CW direction under the control of a selector control part 12 to speed up remedy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-relief ring network system, and more particularly to a path switching system at the time of signal deterioration in a SONET (synchronous optical network) system ring-shaped transmission line.

[0002]

2. Description of the Related Art FIG. 2 is a schematic block diagram of a self-relief ring network system having a SONET type ring-shaped transmission line of this type.

In the figure, a plurality of nodes A to D (four nodes are shown for simplification, but more nodes are generally included) are connected to each other by a ring-shaped transmission line 1. Of course, all the nodes A to D have the same function, but in the example of FIG. 2, the node A is the receiving node, the node D is the relay node (through node), and the node C.
Is shown as a transmitting node, only its functional parts are shown as blocks, and the node B is shown simply as a black box.

CCW from transmitting node C (counterclockwise)
STS1 level signal, which is the transmission signal of the
At, the deterioration state is detected by the signal deterioration detection unit 10. In this case, even if the signal deterioration is detected, it is not particularly reported to the next-stage node A, and only the transmission signal is relayed.

In the receiving node A, the signal deterioration detecting section 11 on the CCW side detects the deterioration state of the transmission signal. If the deterioration is equal to or more than a threshold value, the selector controlling section 12 detects it and the selector 14 operates. Switching is controlled. As a result, the CW (clockwise) path (node C → node B →
Path switching is performed so that the transmission signal of the node A) is received, and self-relief processing is performed.

The signal deterioration detecting section 13 detects the deterioration state of the transmission signal of the CW side path.

As an example of signal deterioration detection of each of these signal deterioration detecting units 10, 11, and 13, there is an error detection using an error detection method using an error detection correction code attached to a transmission signal in advance. The error occurrence rate per unit time is calculated by detecting how many errors have occurred within a specified time, and this is compared with a specified value.

[0008]

In such a conventional path switching method in the self-relief ring network, the STS1 signal deterioration detection is performed at each node for the signal deterioration of the transmission line, so that the detection time is long. There is a problem of becoming.

As described above, this signal deterioration detection is, of course, because the error occurrence rate per unit time is calculated by detecting how many errors have occurred within a specified time by performing error detection. Moreover, the signal deterioration detection time becomes long.

Therefore, the present invention has been made to solve the drawbacks of the prior art, and an object of the present invention is to make it possible to quickly switch the signal path in response to a signal deterioration state. The purpose is to provide a self-relief ring network system.

[0011]

According to the present invention, a plurality of nodes and a ring-shaped transmission line connecting these nodes in a ring shape are provided, and the transmission on the unidirectional path of the ring-shaped transmission line is performed. A self-relief ring network system that detects a signal deterioration and switches to a path in the other direction, in which a relay node detects deterioration of a transmission signal on a path in one direction and superimposes alarm information on this transmission signal. At least, and the next-stage node has at least a means for detecting the alarm information included in the transmission signal on the one-way path and switching to receive the transmission signal on the other-direction path. A self-relief ring network system is obtained.

[0012]

The present invention will be described below with reference to the drawings.

FIG. 1 is a system block diagram of an embodiment of the present invention, and the same portions as those in FIG. 2 are designated by the same reference numerals. Also in this embodiment, the case where four nodes A to D are connected by the ring-shaped transmission line 1 is shown for simplification, but generally more nodes are provided.

Although each of the nodes A to D has the same function, in the illustrated example, the node A is the receiving node, the node D is the relay node (through node), and the node C.
Is a sending node, and each functional part thereof is shown as a block. Incidentally, the node B is a relay node in this example and is equivalent to the node D, but is shown as a black box.

The relay node D includes a signal deterioration detector 10, a controller 21, a VT AIS (Virtual Tributary).
Alarm indication signal) insertion section 22. The signal deterioration detection unit 10 is the same as the conventional one, and the control unit 21 controls the VT AIS insertion unit 22 when the error occurrence rate per unit time detected by the signal deterioration detection unit 10 becomes a specified value or more. Is instructed to generate alarm information and insert it into the transmission signal.

The VT AIS inserting section 22 receives the VT AIS of the STS1 signal on the transmission line according to an instruction from the control section 1.
By setting all the constituent bits of the frame to, for example, all "1", the alarm information is sent to the next-stage node A.

The next-stage node (in this case, the receiving node A) receives the VT AIS in the STS1 signal from the relay node D.
VT A that detects that the frame is all "1"
The IS detector 23 (CCW side) is provided. Also,
A VT AIS detector 24 is also provided on the CW side.

When the VT AIS detection section 23 detects all "1" s in the VT AIS frame which is the alarm information, the selector control section 12 responds to this by the selector 1
4 is controlled to be switched so that the CW side path is selected instead of the CCW side path of the ring transmission line.

If signal deterioration occurs during signal transmission on the CW side path, it is detected in the relay node B and the VT AIS frame is set to all "1" as alarm information. Therefore, in the receiving node A at the next stage, the VT on the CW side
This is detected by the AIS detection unit 24, and the selector 14 switches from the CW side path to the CCW side path.

[0020]

As described above, according to the present invention, when the deterioration of the STS1 signal is detected in the through node, the alarm information is superposed and inserted into the STS1 signal. If the path switching is performed by detecting the above, the path switching operation is immediately performed, and there is an effect that a quicker response than the conventional case becomes possible.

[Brief description of drawings]

FIG. 1 is a system block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional self-relief ring network system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ring transmission line 10, 11, 13 signal deterioration detection part 12 selector control part 14 selector 21 control part 22 VT AIS insertion part 23, 24 VT AIS detection part A to D nodes

Claims (2)

[Claims] 1. A plurality of nodes, and a ring-shaped transmission line connecting these nodes in a ring shape, wherein deterioration of a transmission signal on one path of the ring-shaped transmission line is detected to detect the deterioration of the transmission signal of the other direction. In a self-relief ring network system for switching to a path, a relay node has at least means for detecting deterioration of a transmission signal on a one-way path and superimposing alarm information on this transmission signal, and a next-stage node Is a self-relief ring network system having at least means for detecting the alarm information contained in the transmission signal on the one-way path and switching it to receive the transmission signal on the other-direction path. 2. The ring network is a synchronous optical network (SONET), the transmission signal is an STS1 level signal, and the VT AIS (virtual tributary alarm indication signal) of the STS1 signal is used as the alarm information. 2. The self-relief ring network system according to claim 1, wherein the constituent bits are set to the same value.