JP2013085013A - Communication device and method for detecting fault of communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a communication path fault in a communication network without influencing on a main signal band even for a signal the data traffic amount of which cannot be estimated in advance.SOLUTION: A communication device comprises: a transmission processing unit which is connected to a communication network and transmits a main signal to an opposite communication device; and a reception processing unit for receiving a main signal from the opposite communication device. The transmission processing unit comprises: a main signal detection unit for detecting a vacancy in the band of a main signal to be transmitted; a maintenance operation signal generation unit for generating a maintenance operation signal if the main signal detection unit has detected the vacancy in the band of the main signal; and a maintenance operation signal insertion unit for inserting the generated maintenance operation signal into the main signal. The reception processing unit comprises: a main signal detection unit for outputting first fault information if a fault has been detected in the received main signal; and a maintenance operation signal detection unit for outputting second fault information if a fault has been detected from the received maintenance operation signal.

Description

  The present invention relates to a method for detecting a failure in a communication network in a communication apparatus that accommodates a mixture of periodic signals and aperiodic signals.

    In recent years, full IP (Internet Protocol) and Ethernet (registered trademark) have been developed in the backbone network of communication carriers, but the backbone network based on, for example, SDH / SONET technology using time-division multiplexing technology that has existed for a long time. As a result, a backbone network based on, for example, IP / Ethernet technology that transmits information in a packet format, which has started to appear, has existed side by side.

    Under such circumstances, in order to eliminate the inefficiency of equipment and maintenance due to the coexistence of networks, the backbone network based on SDH / SONET technology can be created by converting the conventional SDH / SONET signal into an IP / Ethernet packet. In order to consolidate the IP / Ethernet-based backbone network. For example, MPLS-TP (MPLS-Transport Profile) has been studied in IETF (Internet Engineering Task Force) RFC5654 and RFC5860.

    Here, MPLS (Multi Protocol Label Switching) is a technology that supports multiple protocols and can handle a plurality of network layers. MPLS is a technology that adds short fixed information called Label (label) to a packet and forwards it at high speed. Instead of looking at the IP address as in normal routing, it sends the packet by looking at the fixed information called label. Transmission / reception becomes possible. The route of the label packet forwarded by the MPLS can be handled like a single path. In a network using MPLS-TP, by controlling the label table of each node, an explicit route is provided to the IP network, and packets are prevented from being aggregated to a specific route, thereby improving link use efficiency. Is possible.

    Also, in MPLS-TP, in order to support high-quality and stable data transfer when IP / Ethernet packets are formed, ITU-T Y. 1710, Y.M. In 1711, a maintenance operation function called an OAM (Operation And Maintenance) function is provided. Typical examples of the OAM include CV (Connectivity Verification), FDI (Forward Defective Indicator), BDI (Backward Defective Indicator), and FFD (First Fail Detect Detection).

    CV and FFD are functions for confirming the normality of End to End of an MPLS packet. The CV and FFD are inserted from a UNI (User Network Interface) in an MPLS device that is a transmission end point, and in an MPLS device that is a reception end point. Terminated at the UNI. The CV and FFD are transmitted to the opposite device at regular intervals in packet units, and the communication device failure is detected by monitoring the CV and FFD in the opposite device. However, looking at the CV and FFD from the viewpoint of the bandwidth of the communication path, increasing the number of packets and shortening the insertion period increases the bandwidth of the CV and FFD, and accordingly, the bandwidth of the main signal packet becomes tight. there is a possibility.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a countermeasure against the narrowing of the bandwidth of the main signal packet due to the increase in bandwidth of the CV and FFD. The SDH / SONET signal is a fixed band signal, and an MPLS signal encapsulating the SDH / SONET signal always sends out a signal at a constant period. Therefore, if the main signal is interrupted, it is considered that a failure has occurred in the middle of the communication path. Therefore, it is considered that a signal for detecting a communication path disconnection such as CV and FFD of the OAM signal is unnecessary. Thus, by providing the main signal with a CV or FFD function, it is possible to allocate a wider band to the main signal, and the main signal band does not become tight.

JP 2011-9811 A

IETF RFC5654, RFC5860 ITU-T Y.M. 1415, Y.M. 1710, Y.M. 1711

Since the synchronization signal such as the SDH / SONET signal is periodic data, the failure of the communication path can be detected by monitoring the data. In addition, asynchronous signals such as IP / Ethernet signals are non-periodic signals, and two methods have been put to practical use as failure detection methods in this case.
(1) The maintenance operation signal is periodically inserted into the main signal data traffic on the transmission side. Further, failure detection between the transmission side and the reception side is performed by detecting a maintenance operation signal on the reception side.
(2) The failure detection is performed by monitoring the main signal data traffic (packet) like the SDH / SONET signal.

    In the case of (1), as shown in FIG. 1- (a), when the main signal data traffic is free, a maintenance operation signal can be inserted, and the main signal data is not discarded. As shown in b), since the maintenance operation signal is inserted with priority when the bandwidth is 100% only for the main signal data traffic, it is necessary to limit the main signal bandwidth, and the main signal data is discarded. I had to. In the case of (2), there is a problem that failure detection cannot be performed when there is no main signal data traffic (period).

    As described above, a band variation signal such as an Ethernet signal is transmitted to the communication path only when there is a signal to be transmitted. Therefore, the band of the communication path can be used efficiently, but there is a guarantee that the signal is always transmitted. Even if a failure occurs in the communication path, maintenance / operation such as not being able to determine whether the communication side is simply sending a signal or whether a failure has occurred in the middle of the communication path cannot be detected. There was the above problem.

  In view of the above points, the present invention makes it possible to detect a disconnection or deterioration of a communication path without affecting the main signal band even for a signal whose amount of data traffic cannot be predicted, such as a band fluctuation signal. For the purpose.

  The present invention for solving the problems is a communication device that is connected to a communication network and includes a transmission processing unit that transmits a main signal to an opposite communication device, and a reception processing unit that receives the main signal from the opposite communication device. The transmission processing unit detects a vacancy in the band of the main signal to be transmitted, and a maintenance operation for generating a maintenance operation signal when the main signal detection unit detects a vacancy in the band of the main signal. A signal generation unit; and a maintenance operation signal insertion unit that inserts the generated maintenance operation signal into the main signal. When the reception processing unit detects a failure in the received main signal, A main signal detection unit that outputs failure information and a maintenance operation signal detection that outputs second failure information when a failure is detected from the received maintenance operation signal.

  Further, the maintenance operation signal generation unit periodically generates the maintenance operation signal.

  Further, the maintenance operation signal generation unit stops generating the maintenance operation signal when the main signal detection unit detects that there is no space in the band of the main signal.

  In addition, the reception processing unit is configured to receive a reception signal disconnection detection signal when a reception signal detection unit that detects presence / absence of a reception signal is reset and is not reset for a predetermined period when the reception signal detection unit detects that there is a reception signal. It has the period timer counter part which outputs.

    According to the present invention, when the data traffic of the main signal fluctuates like a band fluctuation signal and the failure of the communication path for transmitting the signal whose data traffic volume cannot be predicted in advance is detected, the maintenance operation signal is converted into the main signal data. By inserting only when there is free traffic, the main signal data is prevented from being discarded when there is no free main signal data traffic. Can be detected.

It is the figure which showed the influence on main signal data by insertion of a maintenance operation signal. It is a network configuration example using an MPLS device. It is a hardware structural example of an MPLS apparatus. It is a hardware structural example of a GbE-UNI board. It is a functional block diagram of a transmission processing part. It is a flowchart of a transmission process. It is a functional block diagram of a reception processing unit. It is a flowchart of a reception process.

  As an example of an embodiment for carrying out the invention, a description will be given based on MPLS-TP technology represented by technology for aggregating signals such as SDH / SONET signals and Ethernet signals into a packet-based backbone network.

  FIG. 2 shows an example of a construction diagram of the MPLS network system according to the present embodiment. The stations 100-1 to 100-4 are connected to each other by the MPLS devices 200-1 to 200-4 via a signal communication path (solid line), and the MPLS devices 200-1 to 200-4 are ring-shaped. The MPLS network 1000 is configured. In the station 100-1, the user apparatuses 300-1 to 300-2 input the SDH / SONET signal and the Ethernet signal to the MPLS apparatus 200-1. The MPLS device 200-1 encapsulates signals of different formats into an MPLS signal, and transmits it to the opposite MPLS device (for example, the MPLS device 200-2). The destination MPLS apparatus 200-2 decapsulates the MPLS signal into an SDH / SONET signal and an Ethernet signal, and distributes them to each user apparatus. The MPLS devices 200-1 to 200-4 are connected to each other via a control line (broken line) different from the signal communication path, and the MPLS devices 200-1 to 200-4 in the MPLS network 1000 are connected to each other. The state of the signal communication path is managed by the network management device 400 connected to each of the MPLS devices 200-1 to 200-4. The network management apparatus 400 communicates with each of the MPLS apparatuses 200-1 to 200-4 in the MPLS network 1000, and manages OAM information including a failure such as a communication path disconnection of each of the MPLS apparatuses 200-1 to 200-4. . The network management device 400 centrally manages failures between the MPLS devices 200-1 to 200-4 in the MPLS network 1000 at a remote location, a maintenance center, etc., and manages the MPLS devices 200-1 to 200-4. It can be managed and operated.

  FIG. 3 shows an example of a hardware configuration diagram of the MPLS apparatus. The MPLS device includes SDH-UNI 210, GbE-UNI 220, 10GbE-UNI 230, SW 240, and NNI 250. The SDH-UNI 210 performs encapsulation / decapsulation and multiplexing / demultiplexing of the SONET / SDH signal and the MPLS signal. The GbE-UNI 220/10 GbE-UNI 230 performs encapsulation / decapsulation and multiplexing / demultiplexing of the Ethernet signal and the MPLS signal. The SW 240 switches the communication route. The NNI 250 transmits the multiplexed high-speed signal over a long distance to the opposite communication device. Here, the OAM signal of the maintenance operation signal is subjected to insertion / reception processing in the SDH-UNI 210 and the GbE-UNI 220 / 10GbE-UNI 230.

  FIG. 4 shows an example of a hardware configuration diagram of GbE-UNI. The Ethernet signal output from the user apparatus is photoelectrically converted by the optical module 221, encapsulated by the Ethernet-MPLS converter 222, the OAM signal is inserted by the transmission processor 223, and output to the SW 240. Conversely, the MPLS signal input from the SW 240 is distinguished from the main signal and the OAM signal by the reception processing unit 224. In the case of the main signal, the MPLS signal is decapsulated by the Ethernet-MPLS conversion unit, and is subjected to photoelectric conversion by the optical module 221. To the user device.

  FIG. 5 shows a functional block diagram of the transmission processing unit. The main signal detection unit 223-1 detects the presence / absence of the main signal, and outputs main signal band information, which is the detection result, as a main signal band notification signal. The OAM generation control unit 223-2 determines whether or not there is a main signal band based on the main signal band information. If there is an empty main signal band, the OAM generation control signal outputs an OAM generation start signal using the OAM generation control signal. If there is no available bandwidth, an OAM generation stop signal is output. The OAM generation unit 223-3 generates the OAM signal periodically when the generation start signal is received, and stops generating the OAM signal when the generation stop signal is received. The OAM insertion unit 223-4 inserts the OAM signal into the main signal traffic, and outputs a transmission signal with the OAM signal inserted (hereinafter referred to as a transmission signal).

  FIG. 6 shows a flowchart of the transmission processing process. The main signal detection unit 223-1 of the transmission processing unit 223 starts detecting the presence or absence of the main signal at the start of processing. Thereafter, the main signal band information that is the detection result is transmitted as a main signal band notification signal to the OAM generation control unit 223-2 (A01). The OAM generation control unit 223-2 determines whether or not there is a band based on the main signal band information (A02). If there is an empty main signal band, the OAM generation control unit 222-2 transmits an OAM generation start signal to the OAM generating unit 223-3 (A03). If there is no empty main signal band, an OAM generation stop signal is sent. It transmits to the OAM generation part 223-3 (A06). When receiving the generation start signal, the OAM generation unit 223-3 periodically generates an OAM signal and transmits it to the OAM insertion unit 223-4 (A04). When receiving the generation stop signal, the OAM generation unit 223-3 generates an OAM signal. Is stopped (A07). The OAM insertion unit 223-4 inserts the OAM signal into the main signal traffic and transmits a transmission signal (hereinafter referred to as a transmission signal) into which the OAM signal is inserted to the SW 240. In this way, the transmission processing unit 223 determines the main signal traffic amount, and inserts an OAM signal only when there is a vacancy in the main signal band.

  FIG. 7 shows a functional block diagram of the reception processing unit. The reception signal detector 224-1 detects reception of the reception signal, and outputs a timer reset signal when the reception signal is received. Periodic timer counter unit 224-2 counts the timer, and when the time measured by the counter exceeds a predetermined time, it determines that the communication path is disconnected and outputs a communication path disconnection signal. The received signal determination unit 224-3 determines the input received signal, and outputs the received signal to the main signal processing unit 224-4 when the received signal is a main signal, and the OAM processing unit 224 when the received signal is an OAM signal. Output to -5. The main signal processing unit 224-4 processes the main signal, and outputs a failure information to the alarm processing unit 224-6 when a failure is detected in the main signal. The OAM signal processing unit 224-5 processes the OAM signal, and outputs a failure information to the alarm processing unit 224-6 when a failure is detected by the OAM signal. Upon receiving the failure information, the alarm processing unit 224-6 notifies the network management device 400 that there is a failure.

  FIG. 8 shows a flowchart of the reception processing process. When there is no main signal, the transmission processing unit 223 periodically inserts an OAM signal. Therefore, the transmission signal always transmits the main signal or the OAM signal within a certain time. When the transmission signal (the reception signal in the reception processing unit) is interrupted, it is only when a disconnection failure occurs in the middle of the communication path, and thus the failure can be detected.

  FIG. 8A shows a process for detecting a communication path disconnection. The reception signal detection unit 224-1 of the reception processing unit 224 starts detection of a reception signal (B01) at the start of processing, and also starts the timer count of the periodic timer counter unit 224-2. When the reception signal detection unit 224-1 receives the reception signal, the reception signal detection unit 224-1 resets the counter of the period timer counter unit 224-2 (B02), and returns to Step B01. When the reception signal is not received, it is determined whether the measurement time by the counter of the period timer counter unit 224-2 has exceeded a predetermined time (B03). If the measurement time is within the predetermined time, the process returns to step B01 again to confirm reception of the received signal. When the measurement time exceeds the predetermined time, it is regarded as a communication path disconnection (B04), and the periodic timer counter unit 224-2 notifies the alarm processing unit 224-6 of the communication path disconnection (B05). In this way, communication path disconnection detection is realized.

  FIG. 8B shows a detection process for a failure other than communication path disconnection such as signal degradation. The reception signal determination unit 224-3 of the reception processing unit 224 determines the input reception signal (C01). When the received signal is a main signal, it is transmitted to the main signal processing unit 224-4 (C02), and when the received signal is an OAM signal, it is transmitted to the OAM processing unit 224-5 (C05). When the main signal processing unit 224-4 detects a failure (eg, communication path deterioration), the failure information is communicated to the alarm processing unit 224-6 (C03, C04). When a failure (eg, BDI, FDI) is detected by the OAM signal processing unit 224-5, the failure information is transmitted to the alarm processing unit 224-6 (C06, C07). In this way, fault detection other than communication path disconnection such as signal degradation is realized.

  By the above means, when a main signal is present for a signal whose amount of data traffic cannot be predicted in advance, such as a signal obtained by encapsulating an Ethernet signal in an MPLS signal, failure detection is performed by using the main signal traffic (packet). When the main signal does not exist, the failure detection can be performed without squeezing the main signal band by detecting the failure with the maintenance operation signal.

  The present invention can be applied not only to various band fluctuation signals such as Ethernet / IP and T-MPLS / MPLS-TP but also to various networks to which band-fixed signals such as SDH / SONET signals are applied. In the detailed description of the invention, communication path failures have been mainly described. However, the present invention is not limited to this, and can be applied to in-device failure detection based on communication path settings.

1000 MPLS network 100-1 to 100-4 office building 200-1 to 200-4 MPLS device 210 SDH-UNI board 220 GbE-UNI board 221 optical module 222 Ethernet signal ⇔ MPLS signal converter 223 transmission processor 223-1 main Signal detection unit 222-2 OAM generation control unit 223-3 OAM generation unit 223-4 OAM insertion unit 224 Reception processing unit 224-1 Reception signal detection unit 224-2 Periodic timer counter unit 224-3 Reception signal determination unit 224-4 Main signal processing unit 224-5 OAM processing unit 224-6 Alarm processing unit 230 10GbE-UNI panel 240 SW panel 250 NNI panel 300-1 to 300-8 User device 400 Network management device

Claims (5)

In a communication device including a transmission processing unit that is connected to a communication network and transmits a main signal to an opposite communication device, and a reception processing unit that receives a main signal from the opposite communication device.
The transmission processing unit
A main signal detection unit for detecting an empty band of the main signal to be transmitted;
When the main signal detection unit detects a vacancy in the band of the main signal, a maintenance operation signal generation unit that generates a maintenance operation signal;
A maintenance operation signal insertion unit that inserts the generated maintenance operation signal into the main signal,
The reception processing unit
When a failure is detected in the received main signal, a main signal detection unit that outputs first failure information;
A communication apparatus, comprising: a maintenance operation signal detection that outputs second failure information when a failure is detected from the received maintenance operation signal. The communication device according to claim 1.
The maintenance operation signal generating unit periodically generates the maintenance operation signal. The communication device according to claim 1 or 2,
The maintenance operation signal generation unit stops generation of the maintenance operation signal when the main signal detection unit detects that there is no vacancy in the band of the main signal. The communication device according to any one of claims 1 to 3,
The reception processing unit includes a reception signal detection unit that detects presence or absence of a reception signal;
A communication apparatus comprising: a periodic timer counter unit that outputs a reception signal disconnection detection signal when the reception signal detection unit is reset by detecting the presence of a reception signal and is not reset for a predetermined period. In a communication device that is connected to a communication network and performs communication with a facing communication device,
Detects whether the main signal to be transmitted is available or not,
When detecting a vacancy in the main signal, a maintenance operation signal is inserted into the main signal and transmitted,
When the received main signal includes the maintenance operation signal, the presence / absence of a failure is detected from the maintenance operation signal. When the received main signal does not include the maintenance operation signal, the main signal detects the failure. A failure detection method for a communication device, characterized by detecting presence or absence.

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