Multiplex communications – Fault recovery
Reexamination Certificate
1999-07-27
2003-11-11
Ton, Dang (Department: 2666)
Multiplex communications
Fault recovery
C370S248000, C370S252000, C714S004110, C714S014000, C714S022000
Reexamination Certificate
active
06646981
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In general, the present invention relates to a transmission apparatus and a communication network. More particularly, the present invention relates to detection of a period of time with a transmission line affected due to a failure of a power supply occurring in a transmission apparatus. A period of time with a transmission line affected is a period of time during which a line transmission is affected by a failure of a power supply occurring in a transmission apparatus.
2. Description of the Related Art
When a failure of a power supply occurs in a transmission apparatus employed in a communication network, the transmission apparatus in which the failure of a power supply occurs becomes as a cause of disabled communication in another transmission apparatus communicating with the transmission apparatus including the failing power supply. It should be noted that another transmission apparatus communicating with the transmission apparatus including the failing power supply is also referred to hereafter as an adjacent transmission apparatus. As the power supply is recovered, however, the normal communication is also restored as well. A period of time during which the communication in the transmission apparatuses is not functional due to the failure of a power supply is reported by a center of the communication network to users. As described above, such a period of time is referred to as a period of time with a transmission line affected. In the conventional system, when a failure of a power supply occurs in a transmission apparatus, the fact that an adjacent transmission apparatus becomes incapable of receiving a signal from the failing transmission apparatus is detected by an alarm unit which then transmits alarm information to a monitor/control unit. Then, the alarm information is recorded in a history recording unit. Subsequently, the alarm unit reports the alarm information to a center through a monitoring LAN. The center carries out activities such as general tests, monitoring, restoration tests and line setting of the transmission apparatuses. As the failure of a power supply occurring in the transmission apparatus is fixed, pieces of alarm information collected by the center from transmission apparatuses adjacent to the failing transmission apparatus are output to a printer to indicate how long communication lines have been affected by the failure of a power supply. A person in charge of system maintenance and system supervision then visually examines the pieces of alarm information one piece after another to asses the effects of the failure of the power supply.
However, the conventional transmission apparatus has the following problems.
(1) When a failure of a power supply occurs in a transmission apparatus, each communication line connected to the apparatus is affected till the failure is fixed and the apparatus is restored to a normal state. In a multi-vendor environment involving several vendors supplying software and hardware as well as several vendors doing communication businesses, it is quite within the bounds of possibility that alarm information varies from vendor to vendor. It is thus necessary for the person in charge of maintenance to examine periods of time each with a transmission line affected due to a failure of a power supply occurring in a transmission apparatus one time after another by taking differences in alarm information between vendors into consideration. Such examination requires a long time and it is thus difficult to present a period of time with a transmission line affected to users immediately. In addition, a large-scale communication network normally has a hierarchical structure wherein a plurality of transmission apparatuses connected to a transmission apparatus with,a failing power supply may be centrally monitored by different centers. In this case, each of the centers detects a period of time with a transmission line affected by the transmission apparatus in which the failure of a power supply has occurred. In order to grasp the whole picture of the state, however, it is necessary to collect all periods of time each with a transmission line affected which are detected by a plurality of centers and it thus takes an even longer time to collect such pieces of information. In addition, the person in charge of maintenance has to identify all transmission apparatuses adjacent to the transmission apparatus in which the failure of a power supply has occurred and detect periods of time each with a transmission line affected from pieces of alarm information received from the adjacent transmission apparatuses in order to examine the periods of time each with a transmission line affected. Due to the fact that each of the centers control s a large number of transmission apparatuses, however, it is difficult to manually and in a short time form a judgment as to which transmission apparatuses are involved in communications with the transmission apparatus in which the failure of a power supply has occurred, and the formation of such a judgment thus entails a number of people in charge of maintenance and a long time.
(2) When the failure of a power supply is fixed, the transmission apparatus in which the failure of a power supply has occurred informs a center that the power supply has been recovered and transfers data such as line-setting information from a non-volatile backup memory of the transmission apparatus to a volatile memory of the apparatus to set the state prior to the occurrence of the failure of a power supply before resuming communication. At that time, a secondary failure may occur because of some reasons so that complete line setting becomes impossible. For example, the loading (the transfer) of line-setting information from the non-volatile backup memory to the volatile memory ends in a failure for some lines. In this case, nevertheless, the transmission apparatus in which a failure of a power supply has occurred appears to the center to have been restored to the normal operation by the recovery of the power supply of the transmission apparatus. In actuality, however, an adjacent transmission apparatus connected to a line of which can not be set normally, is still in a state of being incapable of receiving a signal as before. As a result, the adjacent transmission apparatus continues transmitting alarm information to the center. At that time, the person in charge of maintenance needs to identify and fix the secondary failure on the basis of the alarm information. Since the transmission apparatus with the recovered power supply itself does not transmit alarm information, however, it may take time to identify the secondary failure. In addition, in case the power-supply of a transmission apparatus is interrupted during line setting of the transmission apparatus by a center, line-setting information to be transmitted from the center to transmission apparatuses is not reflected in the failing transmission apparatus, but is reflected in the adjacent transmission apparatus. On the other hand, when a transmission apparatus in which a failure of the power supply has occurred resets the connecting lines after the power supply is recovered, no signal is transmitted to an adjacent transmission apparatus, a transmission line of which remains to be set. As a result, the adjacent transmission apparatus is left in a state of being incapable of receiving signals. It is thus naturally desirable to improve the method of recovering the communication network through reduction of the time loss incurred in the recovery by letting the center naturally see alarm information received from a transmission apparatus in which a secondary failure of a power supply has occurred, causing the transmission apparatus incapable of normally setting lines.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a transmission apparatus and a communication network that are capable of detecting periods of time each with a transmission line affected in a short time.
It is another object of the present
Kinouchi Kenya
Ono Takeshi
Fujitsu Limited
Hom Shick
Katten Muchin Zavis & Rosenman
Ton Dang
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