Multiplex communications – Fault recovery – Bypass an inoperative switch or inoperative element of a...
Reexamination Certificate
1999-03-29
2003-10-28
Kizou, Hassan (Department: 2662)
Multiplex communications
Fault recovery
Bypass an inoperative switch or inoperative element of a...
C370S222000, C370S223000
Reexamination Certificate
active
06639893
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication network system comprising a network made from a communication device such as an ATM (Asynchronous Transfer Mode) converter and a network management device that manages the communication devices in this network, and more particularly to improvements in switching control between these devices and in control of display of information relating to faults, structure, and operating status, etc. of the abovementioned communication devices for a network management device when a redundant structure of the abovementioned devices or network management devices, etc. is used to increase fault resistance of the system.
2. Description of the Related Art
For example, in the railway management system and highway management system fields, network structures are known whereby multiple communication devices are installed in a distributed manner, information from each of these communication devices is gathered into one management center, and management is performed. With this type of system, because these are systems with a highly public character since they are used for railways and highways, there is also a demand for them to be fault resistant.
FIG. 47
shows one example of a conventional system of this type that took fault resistance into consideration. This system is realized by an ATM ring system that performs communication between a ring network H made from node devices
81
H,
82
H,
83
H,
84
H,
85
H, and
86
H connected by ring transmission line
25
H and ring network I made from node devices
81
I,
82
I,
831
,
84
I,
85
I, and
86
I connected by ring transmission line
25
I. Using ATM switching technology.
In
FIG. 47
,
70
is a network management device which manages all nodes within ring networks H and I via Ethernet
10
. Also, a local terminal (in the figure, only local terminals
90
H and
90
I connected respectively to node devices
85
H and
85
I are shown) is connected to all node devices within ring networks H and I.
With a system that performs communication between ring networks, if a fault occurs in the transmission line between rings, communication between the rings is cut off, so by providing a duplex transmission line with a current use system and a spare system which can be switched, when a fault occurs in the current use transmission line, by switching to connect to the spare system transmission line, redundancy between the ring networks is achieved with a method that continues communication between rings.
With the ring network system shown in
FIG. 47
,
84
H and
84
I are between-ring connection node devices for connecting adjacent ring networks, and these are connected by duplex between-ring transmission line
35
which can be switched to either the current use system or a spare system.
For this between-ring transmission line
35
, normally, communication between ring networks is performed using the current use system transmission line
351
, but when a fault occurs with the current use system transmission line
351
, this is detected by facing between-ring connection node devices
84
H and
84
I, and by switching transmission line
35
to the spare system transmission line
352
and controlling, it is possible to continue communication between the rings.
In this way, with the ring network system shown in
FIG. 47
, when a fault occurs in the current use system transmission line, by switching to the spare system transmission line and performing control, it is possible to continue communication between rings.
However, with this conventional system, there is the problem that when line duplex switching fails, or when a fault occurs directly with the between-ring connection node devices
84
H and
84
I that perform line duplex control, not only is it impossible to perform line duplex switching due to the line fault, or due to a fault of between-ring connection node device
84
H and
84
I, normal communication between rings is not possible.
FIG. 48
shows another example of this type of conventional system. The basic structure of the system shown in
FIG. 48
is also an ATM ring network made from multiple ATM ring networks. In particular with this system, as will be described later, from the fact that the arrangement is such that control node devices are placed within the ring network to manage each node device in the network, this is called a centralized control type ATM ring network system.
With the system shown in
FIG. 48
, one control node device
81
J is allocated within a ring network J, and this control node device
81
J performs centralized control of all ring node devices
82
J through
86
J within the ring network J. Similarly, one control node device
81
K is allocated within a ring network K, and this control node device
81
K performs centralized control of ring node devices
82
K through
86
K.
For the ring network J and the ring network K, the node device
84
K and the node device
84
J (
84
K and
84
J correspond to the between-ring connection node devices
84
H and
841
of the system shown in
FIG. 47
) are connected by a transmission line
36
.
With an ATM ring network with this kind of structure, as a measure for improving fault resistance, methods such as duplexing of transmission lines are used.
FIG. 49
shows an example of a duplex transmission line. As shown in FIG.
49
(
a
), the ring network J has a duplex structure of the current use system line
251
and the spare system line
252
for the transmission line that connects the control node device
81
J and the ring node devices
82
through
86
.
For this ring network J, for example, when a fault occurs at the transmission line
25
J between the ring node device
84
J and the ring node device
85
J, as shown in FIG.
49
(
b
), by executing loop back for each of the ring node device
84
J and the ring node device
85
J (the standby system line
252
is turned back and connected to the current use system line
251
), a detour is made around the location where the fault has occurred using the standby system line
252
.
As described above, with a centralized control type ATM ring network system, by making duplex transmission lines, even when a fault occurs in a transmission line, the reliability is guaranteed, and even when a fault occurs at the ring node device, it is possible to minimize the effect of the fault by performing loop back with the adjacent ring node device.
However, with centralized control type ATM ring network systems, as a rule, the abovementioned loop back control is implemented under the control of the control node device, and when a fault occurs with a control node device, until the control function is restarted by replacing or repairing the control node device, since it is not possible to perform ring node device control, the ring node device does not operate, causing the problem that all communication is stopped.
However, with the ring network system (
FIGS. 47 and 48
) described above, a network management device
70
is installed and with this network management device, there is a function that manages the devices to be managed such as the control node devices, ring node devices, and between-ring connection node devices within each ring system.
Here, the network management device performs management of the devices to be managed by methods such as displaying self notification information from each device to be managed based on that information, or based on this display, by controlling to a specified operating state of the applicable devices to be managed by sending the control information.
When we consider this structure, it is extremely important not only to install multiple network management devices for the devices to be managed, but also to perform firm network management in order to increase the fault resistance of the system overall.
FIG. 50
shows a conventional communication network system that realizes the viewpoint discussed here.
This system has a network structure that performs management of all devices to be managed
110
L,
111
L,
112
L, and
113
L within
Chikenji Takamitsu
Eri Michiaki
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