Communication network system and loopback control method

Details Communication network system and loopback control method Communication network system and loopback control method

1999-06-09

2003-12-09

Yao, Kwang Bin (Department: 2662)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S249000

Reexamination Certificate

active

06661800

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a communication network system that comprises either one or a plurality of ring systems, wherein a plurality of node devices and a control node device that controls these node devices are connected by a ring-shaped circuit with communication being carried out between an arbitrary number of node devices or between communication terminals connected to each of the node devices through the ring circuit. In particular, the present invention is related to improvements in the transmission relay portion between each of the ring systems when a plurality of the ring systems are provided and to improvements in a loopback control method that deals with expansion and reduction or fault restoration of node devices without interrupting communication in the ring systems.
2. Description of the Related Art
Communication network systems have been considered in which a plurality of node devices which have an ATM (asynchronous transfer mode) switching function are arranged in a ring shape through the ring circuits such as optical fiber used as a system configuration such as a railroad management system or a roadway management system. And in addition, after connecting local communication terminals such as monitoring cameras or monitoring devices to each of these nodes, data between each of the local communication terminals is transmitted and received through each of the node devices by establishing a plurality of virtual communication paths in a ring shape for the ring circuits and using these communication paths.
FIG. 32
shows the basic configuration of this type of communication network system. This system comprises connecting node devices
10
A,
10
B,
10
C,
10
D,
10
E and network control device
9
that controls each of these node devices
10
A,
10
B,
10
C,
10
D,
10
E in a ring shape through the ring circuits that uses, for example, optical fiber.
In a ring system that comprises this type of connection format, node devices
10
A,
10
B,
10
C,
10
D,
10
E (hereinafter referred to as ring nodes) are actualized using a communication device that has an ATM switching function. Further, network control device
9
(hereinafter referred to as control node) actualized using a communication device that adds an additional function to the ATM switching function that controls the ring nodes
10
A,
10
B,
10
C,
10
D,
10
E.
Either one or a plurality of local communication terminals can be connected to each ring node
10
A,
10
B,
10
C,
10
D,
10
E and control node
9
. Only local communication terminal
11
-
1
(connected to ring node
10
D) and local communication terminal
11
-
2
(connected to ring node
10
E) are shown in this figure.
Communication between these local communication terminals
11
(
11
-
1
,
11
-
2
, —) can be carried out by means of a ring-shaped circuit formed between the ring nodes
10
A,
10
B,
10
C,
10
D,
10
E and control node
9
.
In other words, in this system, a ring is actualized by means of connecting each ring node
10
A,
10
B,
10
C,
10
D,
10
E and control node
9
using a bi-directional circuit
6
. In detail, control node
9
and ring node
10
A are connected by a bidirectional circuit comprising circuit
61
-
1
and circuit
62
-
6
. Further, the gap between ring node
10
A and ring node
10
B is connected by a bi-directional circuit comprising circuit
61
-
2
and circuit
62
-
5
. Hereinafter, the gap between ring node
10
B and ring node
10
C, the gap between ring node
10
C and ring node
10
D, the gap between ring node
10
D and ring node
10
E and the gap between ring node
10
E and control node
9
are also the same.
Because of this, this system comprises a ring with a direction defined as clockwise comprising circuits
61
-
1
,
61
-
2
,
61
-
3
,
61
-
4
,
61
-
5
,
61
-
6
and a ring with a direction defined as counterclockwise comprising circuits
62
-
1
,
62
-
2
,
62
-
3
,
62
-
4
,
62
-
5
,
62
-
6
.
In a ring system with this configuration, communication between these local communication terminals
11
is achieved through bi-directional communication that uses a clockwise circuit in an ordinary state. The counterclockwise circuit is operated in a mode reserved for use in a loopback for a circuit fault.
In recent years demands have been increasing to construct network systems which cover a wider range utilizing the ring system shown in
FIG. 32. A
conventional communication network system that meets these demands has the type of configuration shown in FIG.
33
.
This
FIG. 33
shows an example of the configuration of a network system comprising three ring networks A, B, C which for the basis of the ring system shown in FIG.
32
. In this figure, ring system A comprises six ring nodes
10
A-
1
,
10
A-
2
,
10
A-
3
,
10
A-
4
,
10
A-
5
,
10
A-
6
. From among these ring nodes,
10
A-
6
gathers the data of the ring system A and is used as a line-gathering/relaying node that relays signals to an external circuit
14
.
In like manner, ring system B comprises six ring nodes
10
B-
1
,
10
B-
2
,
10
B-
3
,
10
B-
4
,
10
B-
5
,
10
B-
6
and ring system C comprises six ring nodes
10
C-
1
,
10
C-
2
,
10
C-
3
,
10
C-
4
,
10
C-
5
,
10
C-
6
. From among these ring nodes,
10
B-
6
gathers the data of ring system B and ring system C and is used as a line-gathering/relaying node that relays signals to an external circuit
14
.
Furthermore, a relay switch
15
is connected to external circuit
14
for the purpose of relaying data from ring nodes
10
A-
6
,
10
B-
6
,
10
C-
6
of the line-gathering/relaying node to an exchange
40
through relay circuit
30
.
As understood from the configuration shown in
FIG. 33
, in this conventional network system, one ring node (
10
A-
6
,
10
B-
6
,
10
C-
6
) from among each of the ring systems A, B, C was used for line-gathering and in addition, it was necessary to provide relay switch
15
to further gather the data.
According to this configuration, in addition to increasing the number of line-gathering nodes in response to the number of ring systems, each line-gathering node had to be arranged at a position where a relay is carried out which worsened the efficiency of the node utilization.
Furthermore, a case was also considered from the viewpoint of improved communication reliability for relay system that is doubled in the line-gathering/relaying of the data of a ring system. For this case however, specialized devices were necessary to control these doubled relay systems.
It has also been considered to use a ring system having the type of configuration shown in
FIG. 32
in a railroad management system or a roadway management system. Because of this, particularly strong emphasis has been placed on communication reliability.
From the viewpoint of this type of improved communication reliability, when a fault occurs in this type of system, a loopback control function is normally provided that helps with communication by looping back the communication path using two ring nodes adjacent to the location where the fault occurred forming a communication path that bypasses the location where the fault occurred.
Moreover, this loopback control function is also utilized when expanding or reducing ring nodes.
FIG. 34
to
FIG. 36
shows changes in of the loopback control when expanding the ring nodes in a conventional ring system. Further, the ring system of
FIG. 34
to
FIG. 36
may be considered to use camera
11
A as local communication terminal
111
and to use monitor device
11
B as local communication terminal
11
-
2
in the ring system shown in FIG.
32
.
Normally, in this system, camera
11
A (connected to ring node
10
D) and monitor device
11
B (connected to ring node
10
E) communicate through clockwise communication path
61
set within transmission path
6
. At this time, communication path
61
and counterclockwise communication path
62
are in reserve to control the loopback.
When an attempt is made to expand ring node
10
F between, for example, ring node
10
A and ring node
10
B during communica

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