Multiplex communications – Fault recovery – Bypass an inoperative station
Reexamination Certificate
1998-07-13
2001-10-16
Chin, Wellington (Department: 2664)
Multiplex communications
Fault recovery
Bypass an inoperative station
C370S228000, C370S238000, C370S248000, C370S468000
Reexamination Certificate
active
06304547
ABSTRACT:
TECHNICAL FIELD
The invention relates to a method for controlling a communication path in a communication network system including a plurality of unit network, each of which, as a basic unit, has a plurality of communication devices accommodating a single or plurality of local communication terminals and which are connected through a single communication path, in which if a trouble such as a line disconnection took place within a certain unit network, an alternate communication path running via other unit network is formed to relieve communications between local communication terminals adjacent to the troubled point.
BACKGROUND ART
For example, in the fields of railroad control, road control and the like, in order to know the operating conditions of signals and crossings or traffic density on roads, there is used a system in that communication terminals which monitor such conditions and transmit the monitored results are located at respective monitoring spots, and the monitored results are collected from the respective communication terminals (monitoring terminals) and used to control.
A known example of the connection style of such a type of control system is a network, which connects a plurality of communication devices accommodating a single or plurality of local communication terminals through a path according to an ATM (asynchronous transfer mode) switching method to transmit/receive information among the respective local communication terminals through the above path via the corresponding communication device. The individual local communication terminal is located at each monitoring spot to serve as a monitoring terminal to make monitoring and transmit the monitored results.
Besides, development is being made these days on a system which has the above-described network determined as a basic unit and has a connection style to accommodate such a unit network in multiple numbers.
FIG. 11
is a schematic diagram showing an example of such a connection style of a conventional communications network system, which consists of a unit network
1
and a unit network
2
. In the respective unit networks
1
,
2
, reference numeral
30
denotes remote communication devices (divided into R
1
through R
7
and R
8
through R
14
for convenience of description). And, they are connected in a bus configuration through a path according to, for example, the ATM communication method. And, these remote communication devices
30
accommodate a single or plurality of local communication terminals
40
, respectively.
In the aforementioned conventional communications network system, the unit networks
1
,
2
independently form a communication connection. And they are generally not connected physically even if they are adjacent to each other. Therefore, if a trouble such as a line breakage occurred in the unit network
1
, an alternate path running via the other unit network
2
could not be used to relieve communications between local communication terminals
40
which are adjacent to the troubled spot.
For example, it is assumed that a disconnection fault (marked X) occurs between the remote communication device R
3
and the remote communication device R
4
as shown in
FIG. 12
when the local communication terminal
40
connected to the remote communication device R
4
and the local communication terminal
40
connected to the remote communication device R
6
are communicating normally in the unit network
1
as shown in FIG.
11
. Then, the communication route of the local communication terminal
40
connected to the remote communication device R
4
and the local communication terminal
40
connected to the remote communication device R
6
is changed as shown
FIG. 12
, so that communications between the local communication terminal
40
connected to the remote communication device R
4
and the local communication terminal
40
connected to the remote communication device R
6
can be relieved. However, if the aforementioned trouble (disconnection fault between R
3
and R
4
) occurred while communicating between the local communication terminal
40
connected to the remote communication device R
2
and the local communication terminal
40
connected to the remote communication device R
5
, the communications between the remote communication device R
2
and the remote communication device R
5
are lost due to the disconnection fault. As a result, the local communication terminal
40
connected to the remote communication device R
2
and the local communication terminal
40
connected to the remote communication device R
5
cannot communicate to each other.
For the same reason, if the unit network
1
had a broken path between the remote communication device R
4
and the remote communication device R
5
while communications are being made normally between the local communication terminal
40
connected to the remote communication device R
4
and the local communication terminal
40
connected to the remote communication device R
6
as shown in
FIG. 11
, no communications can be made between the local communication terminal
40
connected to the remote communication device R
4
and the local communication terminal
40
connected to the remote communication device R
6
because of the troubled spot (marked X) as shown in FIG.
13
.
Thus, the aforementioned conventional communications network system having the connection style accommodating a plurality of unit networks does not link neighboring unit networks physically. Therefore, if one unit network had a trouble such as a disconnection fault, alternate communications cannot be made via another unit network, and communications between the local communication terminals adjacent to the troubled spot are disabled, resulting in degrading the reliability of communications.
In view of the circumstances described above, it is an object of the present invention to provide a communications network system and a method for controlling its communication path, that the disadvantages described above are remedied and if a trouble occurred in a unit network, an alternate path running via another unit network can be formed to relieve communications between local communication terminals adjacent to the troubled spot, and reliability of communications can be improved.
The invention also aims to provide a communications network system and a method for controlling its communication path, which are effective to relieve communications in case of a trouble in any one of unit networks forming a bus type connection to connect respective communication devices to a path.
Besides, the invention aims to provide a communications network system and a method for controlling its communication path, which are suitable to relieve communications in case of a trouble in a unit network when a path connecting respective communication devices within the unit network comprises a circuit according to an ATM communication method.
SUMMARY OF THE INVENTION
The invention of claim
1
relates to a communications network system including a plurality of unit networks wherein a plurality of communication devices, which respectively accommodate a single or plurality of local communication terminals, are connected through a single communication path to communicate among the respective local communication terminals through the communication path via corresponding communication devices, characterized in that the communications network system comprises: internetwork connection circuits provided among the unit networks; trouble detecting means for detecting a trouble occurred in the respective unit networks; and alternate communication path forming means which, when a trouble is detected by the trouble detecting means, connects a communication path of a first unit network having the trouble to a communication path of a second unit network which is adjacent thereto through the internetwork connection circuits to form an alternate communication path bridging to the second unit network between two communication devices adjacent to a troubled spot within the first unit network.
The invention of claim
2
Tsuruta Hidekazu
Uwajima Kazuo
Chin Wellington
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaihsa Toshiba
Phan M.
LandOfFree
Communication network system and controlling of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Communication network system and controlling of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Communication network system and controlling of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2614832