JP2882338B2 - Path selection method for one-way path switching ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-division multiplexing ring network, and more particularly to a path selection method for a two-fiber unidirectional path switching ring for preventing a delay difference between transmission and reception transmission lines.

[0002]

2. Description of the Related Art A ring network is known as a system configuration for maintaining reliability without impairing economy in constructing a network. As shown in Tables 1 and 2, the ring networks are mainly classified according to the difference between the two forms.

[0003]

[Table 1]

[0004]

[Table 2]

[0005] Among the ring networks classified according to the above differences in form, the number of fiber cores is small (economical efficiency), the number of nodes is large (flexibility), and multiple faults are handled (reliability).
As a ring having such advantages, a two-fiber one-way path switching ring can be cited.

In a two-fiber one-way path switching ring,
For example, a signal is transmitted in one direction using a pair of optical fibers, and switching is performed for each path to recover from a failure.

FIG. 6 shows an outline of a conventional switching process of a two-fiber one-way path switching ring. As shown in FIG. 6A, when the node is started up or in the normal state, for example, regarding the node A ', the transmission transmission route from the WEST system of the node A' to the EAST system of the node B 'and the node B' Is different from the reception transmission route from the WEST system to the EAST system of the node A ′, and the transmission / reception transmission route is another route on the same path.
There is a delay difference in the transmission / reception transmission path at nd. In contrast,
As shown in FIG. 6 (B), when a failure occurs, the transmission and reception transmission route on the same path becomes the same because the rescue is performed by path switching, but the delay of the transmission and reception transmission line before and after the rescue greatly varies. Become.

[0008]

In the above-described conventional two-fiber one-way path switching ring, the switching control is only a process of selecting a path signal at the receiving end, so that a switching control protocol between nodes is unnecessary. Although it has the advantage of,
Since the transmission and reception transmission route may be different routes in the same path, there is a delay difference between the transmission and reception transmission line at the end-to-end of the path, and the transmission and reception transmission line when rescue by path switching is performed when a failure occurs However, there is a problem that the delay of the data varies greatly.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and in a one-way path switching ring, the transmission and reception transmission routes in the same path are always made the same to minimize the delay difference between the transmission and reception transmission lines and to reduce the delay. It is an object of the present invention to provide a path selection method of a one-way path switching ring which effectively prevents the fluctuation of the path.

[0010]

In order to achieve the above object, according to the present invention, each node of a one-way path switching type ring network detects a switching trigger for performing a path switching at a receiving end of its own node. Switching trigger detecting means (DET unit) and switching trigger inserting means (IN) for transmitting a switching trigger for performing path switching to the receiving end of the opposite node.
S unit), a transmission route monitoring unit (SV unit) for monitoring whether the transmission / reception transmission routes on the same path of the switching trigger detection unit (DET unit) and the switching trigger insertion unit (INS unit) match, and an own node. saw including a receiving end switching means (SEL unit), the performing of the receiver switching the transmission route monitoring
The means (SV unit) is the switching trigger detecting means for two routes.
(DET unit) output to switch the receiving end
Of receiving end switching at own node by receiving
Output selection information to the receiving end switching means (SEL unit)
Means and route selection information for receiving end switching at the own node
Output to the switching trigger insertion means (INS unit) for the route
Means for transmitting to the opposing node by
You .

The present invention provides a one-way path switching type ring network.
Each of the nodes of the network
Always send path selection information (for example, P-FERF) bidirectionally
To trigger the switching of the receiving end of the path.
Transmission and reception transmission routes can be made the same.
You .

[0012]

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

FIG. 1 is a block diagram showing a configuration of each node of a one-way path switching ring according to an embodiment of the present invention.

Referring to FIG. 1, each node of the one-way path switching ring according to the present embodiment includes a switching trigger detecting unit (hereinafter, referred to as a “DET unit”) that detects a switching trigger for performing path switching at a receiving end of the own node. ), Switching trigger insertion units (hereinafter also referred to as “INS units”) 2 and 3 for sending a switching trigger to the receiving end of the opposing node, and monitoring the coincidence / mismatch of transmission / reception transmission routes on the same path. A transmission route monitoring unit (hereinafter, also referred to as an “SV unit”) 5 and a receiving end switching unit (hereinafter, referred to as a “SEL unit”) that switches the receiving end of its own node.
6).

WEST switching DET 1 and EAST D
The ET unit 4 uses the fault information of the corresponding path (for example, using a path alarm display signal (hereinafter abbreviated as “P-AIS”)).
And the receiving end path selection information of the opposing node (for example, using a path far end reception failure signal (hereinafter abbreviated as “P-FERF”)) and outputs it to the SV unit 5.

First, the SV unit 5 includes a WEST DET unit 1.
A normal path is recognized from the failure information (for example, P-AIS) of the corresponding path transmitted from the EAST system DET unit 4. Here, when the abnormal path is recognized, the path switching information is output to the SEL unit 6 in order to switch the receiving end to the normal path. If both paths are recognized to be normal, the SEL is used to select the same route (WEST system or EAST system) as the opposite node from the receiving end path selection information (for example, P-FERF) of the opposite node. The path switching information is output to the unit 6.

The SV unit 5 further notifies the opposing node of the path selection of the own node to the WEST system INS unit 2 or the EAST system INS corresponding to the route selected by the own node.
Instruct one of the units 3 to send the receiving end path selection information, and check the EAST INS of the route not selected by the own node.
It instructs one of the unit 3 and the WEST system INS unit 2 to transmit the receiving end path non-selection information. When P-FERF is used as the receiving end path selection information, P-FERF is not transmitted to the route selected by the own node, and P-FERF is sent only to the route not selected by the own node. Is sent.

In response to this, each of the WEST system INS unit 2 and the EAST system INS unit 3 of the two routes sends the receiving node path selection information of its own node (for example, PF
ERF) at all times.

Note that the same processing is performed in the opposite node facing the own node under the same configuration.

As described above, each node of the one-way path switching ring always transmits the receiving end path selection information (eg, P-FERF) in its own node in both directions, and serves as a trigger for switching the receiving end of the path. This makes it possible to realize the same transmission / reception transmission route.

FIGS. 2 to 5 are diagrams for explaining the one-way path switching ring switching process according to one embodiment of the present invention.

FIG. 2 shows the path selection status when the node is started up or in the normal state, and the transmission status of the receiving end path selection information in the INS unit.

Referring to FIGS. 1 and 2, since the WEST system is selected as the receiving path of the node A and the EAST system is selected as the receiving path of the node B, the transmission and reception transmission routes are the same. ing. Here, the node A sends the receiving end path selection information in the west system INS unit 2, and the opposite node sends out the receiving end path selection information in the east system INS unit 3. In FIG. 2, “２” indicates P
-Means that FERF is not sent, and "x" means PF
It means sending an ERF.

FIGS. 3 to 5 show WEST of node A.
The state transition of the switching process when a path failure occurs in the system receiving path is shown.

Referring to FIGS. 1 and 3, W of node A
In the EST system DET unit 1, path failure information (for example, P-AI
S), the SEL unit 6 switches the receiving end to a normal EAST path, and the EAST INS unit 3
Sends the receiving end path selection information (switching procedure 1). In FIG. 3, “○” means that P-FERF is not sent, and “×” means that P-FERF is sent.

As described above, in the switching procedure 1, when the receiving end of the path is switched from the WEST system to the EAST system due to the path failure, the reception transmission route of the node A is changed from the inner route to the outer route. Will be.

Next, referring to FIGS. 1 and 4, in the node B, the receiving end path selection information of the two routes sent from the node A by the switching procedure 1 described above is transmitted to the DET units 1, 4
To detect that the reception transmission route of the node B is changed from the outer route to the inner route, and the SEL unit 6 performs WES to make the transmission / reception transmission route the same route.
The receiving end is switched to the T-system path (switching procedure 2).

At the stage before the switching procedure 2 is performed, since the receiving path of the two routes of each node is normal in both directions, the receiving transmission route is the outer route and the transmitting transmission route is also the outer route. Thus, the transmission / reception transmission route uses a bidirectional different route (different route) (see FIGS. 3 and 4).

Next, referring to FIG. 1 and FIG. 5, the receiving end is switched to the west path in the node B, and the receiving end path selection information (for example, P-FERF) is transmitted by the west INS unit 2. (Switching procedure 3). In addition,
In FIG. 5, “意味” means that P-FERF is not sent, and “×” means that P-FERF is sent.

As described above, in the switching procedure 3, the reception transmission route of the node B is changed from the external route to the internal route, so that the transmission / reception transmission route becomes the same.

By performing the switching process in accordance with the above-described series of procedures, the transmission and reception transmission route can be the same at any time of starting up the node, in the normal state, and when a path failure occurs.

While one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, but includes various embodiments according to the principle of the present invention.

[0033]

As described above, according to the path selection method of the one-way path switching ring of the present invention, transmission / reception on the same path is performed at any time of node startup, normal state, and occurrence of a path failure. Since the transmission route can be made the same, the delay difference between the transmission and reception transmission lines can be minimized, and the variation in delay can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of each node of a one-way path switching ring according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a path selection state when a node of a one-way path switching ring according to an embodiment of the present invention starts up or in a normal state, and a transmission state of receiving end path selection information in an INS unit. .

FIG. 3 is a diagram showing a state transition of a switching process when a path failure occurs in a one-way path switching ring according to an embodiment of the present invention (switching procedure 1).

FIG. 4 is a diagram showing a state transition of switching processing when a path failure occurs in the one-way path switching ring according to an embodiment of the present invention (switching procedure 2).

FIG. 5 is a diagram showing a state transition of switching processing when a path failure occurs in the one-way path switching ring according to the embodiment of the present invention (switching procedure 3).

FIG. 6 is a diagram for explaining a conventional one-way path switching ring switching process. (A) shows the path selection status at the time of node startup or normal state, and (B) shows the path selection status at the time of occurrence of a path failure.

[Explanation of symbols]

 1 West system switching trigger detection unit (DET unit) 2 West system switching trigger insertion unit (INS unit) 3 EAST system switching trigger insertion unit (INS unit) 4 EAST system switching trigger detection unit (DET unit) 5 Transmission route monitoring unit (DET unit) SV section) 6 Receiving end switching section (SEL section) 7 WEST system transmission line 8 WEST system transmission line 9 EAST system transmission line 10 EAST system transmission line

Continuation of the front page (56) References JP-A-8-331090 (JP, A) JP-A-7-66821 (JP, A) JP-A-5-63698 (JP, A) JP-A-4-322537 (JP) JP-A-4-129348 (JP, A) JP-A-4-96444 (JP, A) IEEE LTS (The Magazine of Lightwave Telecommunications Systems), Vol. 2 No. 4, Nov. 1991, Izaz Haque et al, "Self-Healing Rings in a Synchronous Environment", pages. 30-37 IEEE GLOBECOM '90, Nov. 1990, Tsong-Ho Wu et al, "A Class of Self-Healing Ring Architectures for SONET Network Applications", pages. 403, 2.1-403.2.8 (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/437 INSPEC (DIALOG) JICST file (JOIS) WPI (DIALOG)

Claims (3)

(57) [Claims] 1. A switching trigger detecting means for two routes , in which each node of a one-way path switching type ring network detects a switching trigger for performing path switching at a receiving end of its own node; A switching trigger insertion means for transmitting a switching trigger for performing a path switching to an end, and a switching trigger insertion means for two paths , and an output from the switching trigger detecting means for two paths, and
Node's receiving end switching selection information, and
A means for outputting selection information for switching the receiving end to the receiving end switching means.
And the selection information of the receiving end switching in the own node for two routes.
Output to the switching trigger insertion means and transmitted to the opposite node
A means for, an includes a transmission route monitoring means for monitoring the match / mismatch of transmission and reception transmission route in the same path, the receiving end switching means for receiving end switch of the node, a one-way path switching method Each of the nodes in the ring network
Sends the receiving end path selection information in its own node in both directions.
Always transmit and use it as a trigger for path switching at the receiving end.
With this, the transmission and reception transmission routes can be made the same ,
A path selection method for a one-way path switching ring. 2. A one-way path switching ring network.
Switching path for each node to perform path switching at the receiving end of its own node.
WEST and EAST system switching trigger detection for detecting rigger
Output means and a switching trigger for performing path switching to the receiving end of the opposite node
And EAST system switching trigger insertion
And stage, the match / mismatch of transmission and reception transmission route in the same path monitoring
Transmission route monitoring unit, and a receiving end switching means for receiving end switch of the local node, the EAST-based switching and the WEST system switching trigger detection means for
Replacement trigger detection means detects the failure information of the
Monitoring the transmission route by detecting the receiving end path selection information
Means, and the transmission route monitoring means outputs the WEST system switching trigger.
Sent from the detecting means and the EAST system switching trigger detecting means
Normal path is recognized from the fault information of the corresponding path
If an abnormal path is recognized, switch the receiving end to a normal path.
Output path switching information to the receiving end switching means to perform
If both paths are recognized as normal,
From the receiving end path selection information of
In other words, to select either the WEST system or the EAST system
The path switching information is output to the receiving end switching means, and the transmission route monitoring means further selects the path of its own node.
Is selected by its own node to notify
The WEST system switching trigger insertion means corresponding to the route or
One of the EAST system switching trigger insertion means
Instructs the sending node path selection information to be sent,
The WEST system switching trigger insertion means of the route that is not
Either of the EAST switching trigger insertion means
Instructs sending of the receiving end path non-selection information,
Path far-end reception failure signal (P-FERF) as selection information
When using, the far end of the path to the route selected by the own node
The own node does not transmit the reception failure signal (P-FERF).
The path far-end reception failure signal (P-
FERF) , and in response to this, the WEST system switching trigger insertion means for the two routes is inserted.
Stage and each of the EAST system switching trigger inserting means are
The receiving node path selection information of the own node to the opposite node of this path
Notify constantly , and check each of the above nodes in the one-way path switching ring network.
Sends the receiving end path selection information in its own node in both directions.
Always transmit the signal and use it as a trigger for switching the receiving end of the path.
With this, the transmission and reception transmission route is realized as the same route ,
A path selection method for a one-way path switching ring. 3. The ring network according to claim 1, wherein the one-way path switching ring network is configured using a pair of optical fibers or a two-wire transmission line . Path selection method for one-way path switching ring.