Subscriber line terminal device and loopback test method

• US 20040017965A1
• Filed: 12/03/2002
• Published: 01/29/2004
• Est. Priority Date: 07/29/2002
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Abe, Hideji
• Granted Patent: US 7,355,982 B2
• Time in Patent Office: Days
• US Class Current: 385/24
• CPC Class Codes: H04B 10/035 using loopbacks
• CPC Class Codes: H04B 10/0771 Fault location on the transmission path
• CPC Class Codes: H04B 2210/071 using alarms

Abstract

The present invention provides a subscriber line terminal device, which enables identification of the cause of abnormality when abnormality is detected in remote monitoring of a subscriber line terminating device connected to the terminal device via an optical fiber. The terminal device receives a plurality of monitoring signals sent from the terminating device via the optical fiber, the plurality of monitoring signals indicating normality or abnormality of a plurality of monitored items in the terminating device respectively. When two or more among the plurality of monitoring signals indicates abnormality, the terminal device selects a monitoring signal with high order of priority from among the two or more monitoring signals indicating abnormality, based on a prescribed order of priority.

Claims

1. A subscriber line terminal device, connected by an optical fiber to a subscriber line terminating device, comprising:

a reception unit, which receives a plurality of monitoring signals sent from said subscriber line terminating device via said optical fiber, said plurality of monitoring signals indicating normality or abnormality of a plurality of monitored items in the subscriber line terminating device respectively; and

,

a selection unit, which, when two or more among said plurality of monitoring signals received by said reception unit indicates abnormality, selects a monitoring signal with high order of priority from among the two or more monitoring signals indicating abnormality, based on a prescribed order of priority.

2. The subscriber line terminal device according to claim 1, wherein said plurality of monitoring signals include a first signal, indicating normality or abnormality of a power supply of said subscriber line terminating device;

a second signal, indicating normality or abnormality of a cable connecting said subscriber line terminating device and a user terminal;

a third signal, indicating normality or abnormality of a reception state of optical signals of said optical fiber at said subscriber line terminating device; and

a fourth signal, indicating normality or device abnormality of said subscriber line terminating device; and

wherein said order of priority stipulates the order of priority of said first signal and said second signal, the order of priority of said first signal and said third signal, and the order of priority of said first signal and said fourth signal.

3. The subscriber line terminal device according to claim 1, wherein said plurality of monitoring signals are transmitted from said subscriber line terminating device and received by said reception unit by means of an OAM frame.

4. A subscriber line terminal device, connected by an optical fiber to a subscriber line terminating device, comprising:

a monitoring unit, which monitors normality or abnormality of a plurality of monitored items within said subscriber line terminal device, and outputs at least one alarm signal corresponding to at least one monitored item for which abnormality is detected; and

,

a selection unit, which, when said monitoring unit outputs two or more alarm signals corresponding to two or more monitored items among said plurality of monitored items respectively, selects one alarm signal with high order of priority from among the two or more alarm signals based on a prescribed order of priority.

5. The subscriber line terminal device according to claim 4, wherein said alarm signals includes a signal indicating a device malfunction of said subscriber line terminal device and a signal indicating abnormality of said optical fiber;

and, said order of priority stipulates an order of priority for these two signals.

6. A subscriber line terminal device, connected by an optical fiber to a subscriber line terminating device, comprising:

a monitoring unit, which monitors normality or abnormality of a plurality of monitored items within said subscriber line terminal device, and outputs alarm signals corresponding to monitored items for which abnormality is detected;

a reception unit, which receives a plurality of monitoring signals sent from said subscriber line terminating device via said optical fiber, said plurality of monitoring signals indicating normality or abnormality of a plurality of monitored items in the subscriber line terminating device respectively; and

,

a selection unit, which, when said monitoring unit outputs two or more alarm signals corresponding to two or more monitored items among said plurality of monitoring signals respectively, selects a monitoring signal with high order of priority from among the two or more alarm signals, based on a prescribed order of priority, and, when two or more among said plurality of monitoring signals received by said reception unit indicate abnormality, selects a monitoring signal with high order of priority from among the two or more monitoring signals indicating abnormality, based on said order of priority;

or, when said monitoring unit outputs at least one alarm signal corresponding to at least one monitored item from among said plurality of monitored items, and moreover at least one among said plurality of monitoring signals received by said reception unit indicates abnormality, selects an alarm signal or monitoring signal with high order of priority from among at least one of said alarm signals and at least one of said monitoring signals, based on said order of priority.

7. The subscriber line terminal device according to claim 6, wherein said plurality of monitoring signals include a first signal, indicating normality or abnormality of a power supply of said subscriber line terminating device, a second signal, indicating normality or abnormality of a cable connecting said subscriber line terminating device with a user terminal, a third signal, indicating normality or abnormality of a state of reception of optical signals from said optical fiber by said subscriber line terminating device, and a fourth signal, indicating normality or device abnormality of said subscriber line terminating device;

said alarm signals include a fifth signal, indicating a device malfunction of the subscriber line terminal device, and a sixth signal, indicating abnormality of said optical fiber; and

,

said order of priority stipulates the order of priority of said first and second signals, the order of priority of said first and third signals, the order of priority of said first and fourth signals, the order of priority of said first and sixth signals, the order of priority of said sixth and third signals, and the order of priority of said fifth and sixth signals.

8. The subscriber line terminal device according to claim 6, wherein said selection unit performs selection based on said order of priority when said monitoring unit outputs two or more alarm signals simultaneously or within a prescribed period of time, when two or more monitoring signals indicating said abnormality are received by said reception unit simultaneously or within said prescribed period of time, or, when said monitoring unit outputs at least one of said alarm signals, and moreover at least one of said monitoring signals indicating abnormality is received by said reception unit, simultaneously or within said prescribed period of time.

9. The subscriber line terminal device according to claim 6, wherein said plurality of monitoring signals are transmitted from said subscriber line terminating device, and received by said reception unit, by means of an OAM frame.

10. A subscriber line terminal device having a physical layer device, a logical layer device and an OAM sublayer device, said physical layer device being connected via an optical fiber to a subscriber line terminating device and performing physical layer processing of data communicated via said optical fiber, said logical layer device performing logical layer processing of the data, said OAM sublayer device performing processing of an OAM sublayer constituting part of said physical layer and being connected to said physical layer device and to said logical layer device;

wherein said OAM sublayer device comprises;

a test frame processing unit, which generates a test frame containing a payload portion having test data to perform a loopback test between the OAM sublayer device and said subscriber line terminating device or said physical layer device, which transmits said test frame to said logical layer device, which receives from said logical layer device said test frame returned back from said subscriber line terminating device or said physical layer device, and which inspects the received test frame; and

,

a port unit, which transfers said test frame received from said logical layer device to said physical layer device, and which transfers said test frames received from said physical layer device to said logical layer device; and

wherein

said logical layer device comprises a transfer unit, which transfers said test frame from said test frame processing unit to said port unit, and which transfers said test frame from said port unit to said test frame processing unit.

11. The subscriber line terminal device according to claim 10, wherein:

said test frame contains an identifier of a first port in said transfer unit, connected to said port unit, as a destination address, and an identifier of a second port in said transfer unit, connected to said test frame processing unit, as a transmission source address;

said port unit exchanges said transmission source address and said destination address in said test frame received from said physical layer device; and

,

said transfer unit stores the identifier of said first port in advance;

when a test frame is received from said test frame processing unit, stores the transmission source address of the received test frame as an identifier of said second port, transfers the test frame from said first port to said port unit based on the destination address; and

, when a test frame is received from said port unit, transfers the received test frame from said second port to said test frame processing unit based on the destination address of the received test frame.

12. The subscriber line terminal device according to claim 11, wherein said test frame further contains a frame check sequence, and said port unit recalculates the frame check sequence of the test frame after the exchange of said transmission source address and said destination address of said test frame received from said physical layer, and writes the recalculated frame check sequence to the test frame.

13. The subscriber line terminal device according to claim 10, wherein:

said test frame further contains a virtual LAN tag having an identifier for a virtual LAN;

a virtual LAN is set in advance in said logical layer device, corresponding to an identifier of said virtual LAN connecting a first port connected to said port unit in said transfer unit and a second port connected to said test frame processing unit in said transfer unit; and

,

said transmission unit transfers said test frame from said test frame processing unit to said port unit via said second port and first port, and transfers said test frame from said port unit to said test frame processing unit via the first port and second port, based on the virtual LAN corresponding to the identifier of said virtual LAN of the virtual LAN tag contained in said test frame.

14. The subscriber line terminal device according to claim 10, wherein said payload portion comprises test data and error inspection data for the test data, and said test frame processing unit inspects a returned test frame based on said error inspection data.

15. The subscriber line terminal device according to claim 14, wherein said test frame processing unit sets said inspection data to erroneous values for transmission.

16. The subscriber line terminal device according to claim 10, wherein said payload portion is of variable length.

17. The subscriber line terminal device according to claim 10, wherein said test frame is transmitted and received a plurality of times, and the number of transmission and receptions can be set.

18. The subscriber line terminal device according to claim 10, wherein said physical layer device returns said test frame to said first port unit from within said physical layer device itself.

19. The subscriber line terminal device according to claim 10, wherein said logical layer is a media access control layer, and said test frame is a media access control frame.

20. A loopback test method for a subscriber line terminal device having a physical layer device, a logical layer device and an OAM sublayer device, said physical layer device being connected via an optical fiber to a subscriber line terminating device and performing physical layer processing of data communicated via said optical fiber, said logical layer device performing logical layer processing of the data, said OAM sublayer device performing processing of an OAM sublayer constituting part of said physical layer and being connected to said physical layer device and said logical layer device;

said method comprising;

generating and transmitting to said logical layer device a test frame, containing a payload portion having test data, in order to perform a loopback test between the OAM sublayer device and said subscriber line terminating device or said physical layer device, in said OAM sublayer device;

transferring said test frame from said OAM sublayer device to said physical layer device via said OAM sublayer device, in said logical layer device;

returning said test frame, returned from said subscriber line terminating device or from said physical layer device, to said logical layer device, in said OAM sublayer device;

further returning said test frame, returned from said OAM sublayer device, to said OAM sublayer device, in said logical layer device; and

,

receiving and inspecting said test frame returned from said logical layer device, in said OAM sublayer device.