Alarm suppressing method for optical transmission apparatus

Multiplex communications – Diagnostic testing – Fault detection

Reexamination Certificate

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C370S216000

Reexamination Certificate

active

06594236

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical communication network, and more particularly, to an improved alarm suppressing method for an optical transmission apparatus which is capable of promptly retrieving problems in an optical communication network.
2. Description of the Background Art
In general, a communication network is formed of a plurality of different elements manufactured from different makers. The communication elements generate alarm when there occurs a fault in its own or internal connections. Since the network elements don't recognize topology of communication network, a single fault in the communication network may seriously influence on the operation of other different elements and as a result there may occur a plurality of secondary alarms from the elements. Here, the former alarm is referred to as a root alarm and the latter as a propagation alarm.
Presently, a communication network management is manually controlled by humans. An operator in a central control chamber is directed to analyze kinds of alarms, generated locations, kinds of discharged alarms and locations, etc., on the ground of alarms displayed on a console and users' dissatisfaction. An appropriate solution has been taken according to the analyses. Therefore, if there occurs an error in a single optical line with regard to an optical communication device, it inevitably leads to a communication malfunctioning to a plurality of subscribers. Accordingly, it has been understood significant to analyze the root and propagation alarms with regard to maintenance and management of optical communication devices.
FIG. 1
is a block diagram illustrating an entire network interfacing of a synchronous optical transmission devices, wherein a first linear network
100
, a second linear network
110
and a ring mode network
120
are interfaced to an EMS(element management system)
38
through a LAN (local area network)
36
.
At this time, respective network elements NE in the first and second linear networks
100
,
110
and in the ring mode network
120
have different names depending upon their locations. That is, the network elements
10
,
12
,
14
,
22
in the first and second linear networks
100
,
110
are respectively referred to as a TM (terminal multiplexer) since they form terminal elements. The network elements
16
,
18
,
20
disposed in the middle of the second linear network
110
are respectively called as an ADM (add drop multiplexer). Also, the network elements
24
,
26
,
28
,
30
,
32
,
34
in the ring mode network
120
are respectively referred to as an RM (ring multiplexer).
The EMS
38
serves to monitor the root alarm and propagation alarms generated from the respective network elements NE and the operator employs a computer to implement maintenance and management of optical communication lines.
The optical communication device SDH
155
(synchronous digital hierarchy
155
) employed in the present invention enables communication through 155 Mbps high speed transmission. Here, one optical line represents 1900 lines of telephone circuit. Typically, an optical communication device is required to include two optical lines: one for reception, the other for transmission. Here, a preliminary line may be reserved when necessary.
Specifically, one optical line may be used as 3 lines of 36 Mbps VC
3
(virtual container
3
) class and 63 lines of 2.048 Mbps VC
12
class, one line of VC
3
class and 42 lines of VC
12
class, or 2 lines of VC
3
class and 21 lines of VC
12
class.
FIGS. 2 and 3
show circuit connections at a linear mode and a ring mode, respectively, according to the conventional art. With reference to the drawings, the alarm suppressing method for an optical transmission apparatus will now be explained. For convenience's sake, it is assumed that one line of VC
3
class and 42 lines of VC
12
class are employed as an optical line and an example will be taken in a state in which the optical line
42
of the element
34
in the ring mode network
110
is shorted and causes an obstacle.
As shown in
FIGS. 3 and 4
, when the optical line
42
is broken, the element
34
generates a root alarm STM
1
LOS (LOS denotes loss of signal) of its own through the optical line
42
, and the element
34
transmits to the element
32
a propagation alarm with the information that the element
34
has generated the root alarm STM
1
LOS toward west direction W. As a result, the propagation alarm MSRDI (RDI denotes remote defect indication) is detected from east direction E of the element
32
.
Also, the element
34
generates one propagation alarm TU
3
AIS (AIS denotes alarm indication signal) and generates
42
propagation alarms TU
12
AIS through the VC
12
class circuit. Accordingly, the propagation alarm TU
3
AIS is transmitted to the element
28
at a terminal point of the VC
3
class circuit through the optical lines
44
,
45
,
46
. The propagation alarm TU
12
AIS is transmitted to the element
26
at a terminal point of the VC
12
class through the optical line
45
. As a result, the propagation alarm TU
3
AIS of VC
3
class circuit is detected at west direction W of each of the elements
24
,
26
,
28
, and the propagation alarm TU
12
AIS of VC
12
class circuit is detected at west direction W of the element
26
. At this time, the propagation alarm TU
3
AIS is detected from each of the elements
24
,
26
,
28
with regard to VC
3
class line, and the propagation alarm TU
12
AIS is detected from the element
26
serving as an end terminal, with regard to VC
3
class lines.
Therefore, the element
28
serving as an end terminal of the VC
3
class line transmits the other propagation alarms VC
3
RDI toward both directions thereof through the optical line
46
′,
47
, and the element
26
serving as an end terminal transmits 42 lines of the other propagation alarm VC
12
RDI toward both directions thereof through the optical line
45
′,
46
. As a result, the propagation alarm VC
3
RDI is detected at the element
32
serving as the end terminal of the VC
3
class, and the 42 lines of the propagation alarm VC
12
RDI is detected at the element
30
serving as the end terminal.
Consequently, through the LAN
36
the EMS
38
detects one root alarm LOS, one propagation alarm MSRDI, three propagation alarms TU
3
AIS,
42
propagation alarms TU
12
AIS, one VC
3
class propagation alarm VC
3
RDI,
42
VC
12
class propagation alarms VC
12
RDI. Therefore, the system operator analyzes 90 alarms in total which are displayed on the EMS
38
and understands the connection of the propagation alarms generated from the root alarm LOS and the alarm using the locations and the connection state of the respective elements. Also, in the linear mode network
100
, the same steps as above are taken to understand the optical line which has generated the root alarms.
However, the conventional alarm suppressing method of an optical transmission apparatus requires an operation of ability to recognize mutual connection of the alarms by analyzing a plurality of alarms detected. Further, the conventional alarm suppressing method of the conventional optical transmission apparatus may delay solution of breakdown and incur a time loss, thereby deteriorating system reliability.
SUMMARY OF THE INVENTION
The present invention is directed to overcoming disadvantages of the conventional alarm suppressing method for an optical transmission apparatus.
Therefore, it is an object of the present invention to provide an alarm suppressing method for an optical transmission method capable of automatically analyzing a mutual relation between root alarm and propagation alarm.
It is another object of the present invention to provide an alarm suppressing method for an optical transmission method enabling a prompt implementation of maintenance and management of optical lines by recognizing the optical lines of root alarm generation and analyzing the mutual relation between root alarm and propagation alarm within a short time period.
To achieve the above-d

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