JP2018207299A - Subscriber line terminal apparatus - Google Patents

Abstract

To provide a subscriber line terminal apparatus capable of transmitting a control signal prior to a data signal.SOLUTION: A subscriber line terminal apparatus comprises a band allocation device and a transfer device. In the subscriber line terminal apparatus, the band allocation device includes a control signal transmission part for transmitting a control signal that is a signal relating to control of a subscriber line termination device. The transfer device includes: a control signal queue for acquiring the control signal; a data signal queue for acquiring a data signal to be transmitted to the subscriber line termination device; and a control part which secures a transmission time of a control signal, acquires the control signal from the control signal queue without acquiring a data signal from the data signal queue during the transmission time, and transmits the acquired control signal to the subscriber line termination device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a subscriber line terminal station apparatus.

  Regardless of whether the communication form is fixed or mobile, communication systems with various configurations have been studied. A communication system having an optical fiber as a medium is called an optical access network. As an optical access network system, there are an SS (Single Star) system and a PON (Passive Optical Network) system.

  FIG. 4 is a diagram illustrating an example of the configuration of an optical access network. In the SS system, one subscriber line termination device (ONU: Optical Network Unit) is connected to one subscriber line terminal device (OLT: Optical Line Terminal) via an optical fiber. In the PON system, a plurality of subscriber line terminators are connected to one subscriber line terminal device via an optical fiber and an optical splitter.

  Hereinafter, the direction from the subscriber line terminating device to the subscriber line terminal device is referred to as “upward direction”. Hereinafter, the direction from the subscriber line terminal station device to the subscriber line terminal device is referred to as “downward direction”. Hereinafter, the upstream signal is referred to as an “upstream signal”. Hereinafter, the downstream signal is referred to as a “downstream signal”.

  In the PON system, a plurality of subscriber line terminators share an optical fiber. In order to prevent the collision between the uplink signals, the subscriber line terminal station apparatus controls the timing at which the subscriber line terminal station apparatus transmits the uplink signal. The subscriber line end station device controls the transmission timing of the uplink signal using a message of MPCP (Multi-Point Control Protocol).

  The subscriber line termination apparatus requests the subscriber line end station apparatus to permit transmission of an uplink signal by transmitting a transmission request signal (REPORT message) to the subscriber line end station apparatus. The subscriber line terminal station device gives the subscriber line termination device permission to transmit an uplink signal by transmitting a transmission permission signal (GATE message) to the subscriber line termination device (see Non-Patent Document 1). In the PON system, a subscriber line terminal station apparatus dynamically allocates a band corresponding to a transmission timing to an uplink signal of a plurality of subscriber line terminal station apparatuses by dynamic bandwidth allocation (DBA) in MPCP. assign.

  Conventional subscriber line terminal equipment is implemented with dedicated hardware. In recent years, it has been studied to implement part of the functions of a subscriber line terminal station device in software on a server device in a data center (see Non-Patent Document 2). In Non-Patent Document 2, a part of the management function and the control function of the subscriber line terminal station device and the subscriber line terminal device is executed on the server of the data center. In Non-Patent Document 2, functions related to the management and control can be added simply by changing the software.

IEEE802.3.ah, “IEEE Std 802.3-2012 SECTION FIVE 64. Multipoint MAC Control” L. Peterson et.al., “Central Office Re-architected as a Datacenter”, IEEE Communications Magazine, Vol. 54 (10), pp. 96-101, 2016.

  However, Non-Patent Document 2 assumes that the dynamic bandwidth allocation function is implemented by hardware. In order to calculate dynamic bandwidth allocation at high speed, it is necessary to prepare a large number of calculation resources for each hardware, and there is a problem that the total cost becomes high. Therefore, the dynamic bandwidth allocation function is also converted into software and aggregated in the data center, so that a reduction in computing resources due to the aggregation effect can be expected.

  FIG. 5 is a diagram illustrating an example of a configuration of a station building of an optical access network. In FIG. 5, after separating the transfer system function of the subscriber line terminal equipment and the control / management system function including the dynamic bandwidth allocation function, the subscriber line terminal station implemented by software in the server device of the data center. The apparatus executes high-speed calculation processing such as dynamic bandwidth allocation. On the other hand, the transfer function is implemented by a general-purpose L2 switch or the like. In the configuration, since dynamic allocation functions in a plurality of PONs are concentrated in the data center, it is possible to expect a reduction in calculation resources. The transfer device of the subscriber line terminal device transmits the transmission permission signal transmitted from the bandwidth allocation device (MPCP function unit) of the subscriber line terminal device to the subscriber line terminal device.

  FIG. 6 is a diagram illustrating an example of a state in which transmission of a transmission permission signal is in a waiting state. The control signal queue is a queue for transmitting a control signal. The data signal queue is a queue for transmitting a data signal. The transfer device transmits both a data signal including user data and a control signal such as a transmission permission signal to the subscriber line terminating device via the PON. The transfer device gives priority to the control signal over the data signal and transmits the control signal from the control signal queue.

  However, the conventional subscriber line terminal equipment has a problem that the control signal may not be transmitted with priority over the data signal. That is, when the control signal queue acquires a control signal during transmission of a data signal that is a downlink signal, the transfer device needs to wait for transmission of the control signal until transmission of the data signal is completed. Waiting for transmission of the control signal by the transfer apparatus may affect the time at which the subscriber line terminating apparatus transmits the uplink signal. When the time at which the subscriber line terminating device transmits the uplink signal is affected, the uplink signals may collide with each other in the PON.

  In view of the above circumstances, an object of the present invention is to provide a subscriber line terminal station apparatus capable of transmitting a control signal with priority over a data signal.

  One aspect of the present invention is a subscriber line terminal station device including a bandwidth allocation device and a transfer device, wherein the bandwidth allocation device transmits a control signal that is a signal related to control of the subscriber line termination device. A transmission unit, wherein the transfer device acquires a control signal queue for acquiring the control signal, a data signal queue for acquiring a data signal transmitted to the subscriber line terminating device, and a transmission time of the control signal The control signal is acquired from the control signal queue without acquiring the data signal from the data signal queue at the transmission time, and the acquired control signal is transmitted to the subscriber line terminator. A subscriber line terminal station device.

  One aspect of the present invention is the subscriber line terminal station apparatus described above, wherein the control signal transmission unit transmits a pilot signal in which a transmission time and a transfer amount of the control signal are described, and transmits the pilot signal. The transmission of the control signal is started at a time when a predetermined standby time has elapsed from the time, the control signal queue acquires the control signal and the pilot signal, and the control unit includes the control signal queue Acquiring the data signal from the data signal queue for a period from when the pilot signal is acquired until the transmission time elapses or until transmission of the transfer amount control signal is completed in the transmission time. Instead, the control signal of the transfer amount is acquired from the control signal queue, and the acquired control signal is transmitted to the subscriber line terminating device.

  One aspect of the present invention is the above-described subscriber line terminal apparatus, further comprising a timer that transmits an interrupt signal at a predetermined time, and the control unit is configured to start the process from the time when the interrupt signal is transmitted. The control signal is acquired from the control signal queue without acquiring the data signal from the data signal queue until the transmission time of the control signal elapses, and the acquired control signal is acquired from the subscriber line. Send to end device.

  According to the present invention, the control signal can be transmitted with priority over the data signal.

It is a figure which shows the example of a structure of the optical access network in 1st Embodiment. It is a figure which shows the example of the transmission time ensured using the pilot signal in 1st Embodiment. It is a figure which shows the example of a structure of the optical access network in 2nd Embodiment. It is a figure which shows the example of a structure of an optical access network. It is a figure which shows the example of a structure of the station building of an optical access network. It is a figure which shows the example of the state in which transmission of a transmission permission signal is in a waiting state.

Embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an example of the configuration of the optical access network 1a. The optical access network 1a is a communication system having an optical fiber as a medium. The optical access network 1a includes a PON 2 and a subscriber line terminal station device 3a.

  The PON 2 includes a plurality of subscriber line termination devices 20. The subscriber line termination device 20 is a device that terminates the downlink signal transmitted by the subscriber line terminal station device 3a. The format of the downlink signal is a packet format. The PON 2 is a network in which a plurality of subscriber line termination devices 20 are connected to one subscriber line terminal station device 3a via an optical fiber and an optical splitter. The subscriber line terminating device 20 requests the subscriber line terminal station device 3a to permit transmission of the uplink signal by transmitting a transmission request signal (REPORT message) to the subscriber line terminal device 3a.

  The subscriber line terminal device 3a is a device that terminates an upstream signal. The subscriber line terminal station device 3a transmits a transmission permission signal (GATE message) to the subscriber line terminator 20, thereby giving the transmission permission of the uplink signal to the subscriber line terminator 20 that has transmitted the transmission request signal. .

  The subscriber line terminal station device 3a includes a bandwidth allocation device 30a and a transfer device 31a. The bandwidth allocation device 30a includes an allocation unit 300a. The allocation unit 300a is a functional unit (control signal transmission unit) that transmits a control signal that is a signal related to the control of the subscriber line termination device 20. The allocation unit 300a dynamically allocates a band according to transmission timing (transmission time) to uplink signals of a plurality of subscriber line terminal stations by dynamic band allocation in MPCP. The allocation unit 300a transmits a control signal such as a transmission permission signal to the transfer device 31a. Thereby, the allocating unit 300a can transmit a transmission permission signal to the subscriber line terminating device 20 via the transfer device 31a.

  The transfer device 31a is a device that transfers a downstream signal to the PON2. The transfer device 31a transfers both a data signal, which is a signal including user data, and a control signal to the PON 2. The control signal is, for example, an MPCP message such as a transmission permission signal (GATE message) or an OAM (Operation, Administration, and Maintenance) message. The transfer device 31a may transfer the uplink signal to the band allocation device 30a or an external device.

  The transfer device 31a includes a control signal queue 310a, a data signal queue 320, a control unit 330a, and a transmission unit 340. Part or all of the functional units of the transfer device 31a are hardware functional units such as LSI (Large Scale Integration) and ASIC (Application Specific Integrated Circuit). Some or all of these functional units implemented by dedicated hardware such as an L2 switch may be realized by a processor such as a CPU executing a program stored in the storage unit.

  The control signal queue 310a acquires a control signal such as a transmission permission signal or an OAM message from the allocation unit 300a. The control signal queue 310a holds the acquired control signal. The control signal queue 310a acquires a pilot signal, which is one of the control signals, from the allocation unit 300a. The control signal queue 310a holds the acquired pilot signal. The data signal queue 320 acquires a data signal that is a downlink signal from an external device.

  The control unit 330a acquires the pilot signal from the control signal queue 310a. The control unit 330a acquires the control signal from the control signal queue 310a. The control unit 330a acquires the data signal from the data signal queue 320. The control unit 330a prioritizes the control signal over the data signal based on the pilot signal, and transmits the control signal to the transmission unit 340. That is, the control unit 330a ensures a transmission time for transmitting the control signal to the transmission unit 340 without transmitting the data signal to the transmission unit 340 based on the pilot signal. The control unit 330a transmits the control signal to the transmission unit 340 without transmitting the data signal to the transmission unit 340 at the time included in the secured transmission time. The control unit 330a transmits the data signal to the transmission unit 340 at a time not included in the secured transmission time.

  The transmission unit 340 acquires a control signal that is a downlink signal from the control unit 330a. The transmission unit 340 transfers the control signal to the PON2. The transmission unit 340 acquires a data signal that is a downlink signal from the control unit 330a. The transmission unit 340 transfers the acquired data signal to the PON2. The transmission unit 340 may be integrated with the control unit 330a.

Next, the transmission time secured using the pilot signal will be described.
FIG. 2 is a diagram illustrating an example of the transmission time secured using the pilot signal 100. Allocation section 300a transmits pilot signal 100 to control signal queue 310a before transmitting control signal 101-1 to control signal queue 310a. The pilot signal 100 describes information indicating the transmission time. The transmission time is a time longer than the time required for transmission of the control signal 101 that the allocation unit 300a plans to transmit to the transfer device 31a. In FIG. 2, the transmission time is determined as a time obtained by adding a time during which the allocation unit 300 a can transmit the three control signals 101 scheduled to be transmitted to the transfer device 31 a and a predetermined standby time. The predetermined waiting time is set to a time longer than the time required for the data signal queue 320 to transfer the data signal composed of the maximum length packet to the control unit 330a.

  The reason why the standby time is set to a time longer than the time required to transfer the data signal composed of the maximum length packet is that the control unit 330a performs data transmission at the time when the control signal queue 310a acquires the pilot signal. This is because, when the signal is acquired, the control unit 330a cannot acquire the control signal 101-1 until the transmission of the data signal composed of the maximum length packet is completed. If the allocating unit 300a transmits the control signal 101-1 to the control signal queue 310a immediately after the allocating unit 300a transmits the pilot signal 100 to the transfer device 31a, the control signal queue 310a controls the pilot signal 100. Another waiting time further occurs at the time of transmission to 330a.

  The pilot signal 100 includes information indicating the number of control signals 101 transmitted from the assignment unit 300a to the transfer device 31a. In FIG. 2, the pilot signal 100 describes information representing 3 which is the number of control signals 101 transmitted from the assignment unit 300a to the transfer device 31a. Allocation unit 300a starts transmission of control signal 101-1 at the time when the standby time has elapsed from the time when pilot signal 100 was transmitted to transfer device 31a.

  The controller 330a acquires the pilot signal 100 from the control signal queue 310a. When acquiring the pilot signal 100, the control unit 330a reads information indicating the transmission time from the pilot signal. When acquiring the pilot signal 100, the control unit 330a reads information representing the number of control signals (transfer amount) from the pilot signal.

  When acquiring the pilot signal 100, the control unit 330a acquires the number (transfer amount) of control signals described in the pilot signal 100 from the control signal queue 310a. That is, the control unit 330a acquires the number of control signals 101 described in the pilot signal 100 from the control signal queue 310a before the transmission time elapses from the time when acquisition of the pilot signal 100 is completed.

  The control unit 330a does not acquire the data signal 102 from the data signal queue 320 until the number of control signals 101 described in the pilot signal 100 is acquired from the control signal queue 310a. That is, the control unit 330 a acquires the number of control signals 101 described in the pilot signal 100 from the control signal queue 310 a and then acquires the data signal 102 from the data signal queue 320.

  As described above, the subscriber line terminal station device 3a of the first embodiment includes the bandwidth allocation device 30a and the transfer device 31a. The band allocation device 30a includes an allocation unit 300a as a control signal transmission unit. The transfer device 31a includes a control signal queue 310a, a data signal queue 320, and a control unit 330a. The allocating unit 300a transmits the pilot signal 100 in which the transmission time and transfer amount of the control signal 101, which is a signal related to the control of the subscriber line terminating device 20, is described. Allocation unit 300a starts transmission of control signal 101 at a time when a predetermined standby time has elapsed from the transmission time of pilot signal 100. The control signal queue 310 a acquires the control signal 101 and the pilot signal 100. The data signal queue 320 acquires the data signal 102 transmitted to the subscriber line termination device 20. The control unit 330a ensures the transmission time of the control signal. The controller 330a acquires the control signal from the control signal queue 310a without acquiring the data signal from the data signal queue 320 during the secured transmission time, and transmits the acquired control signal to the subscriber line terminating device 20. To do. That is, the control unit 330a determines whether the data signal, the period until the transmission time elapses from the time when the control signal queue 310a acquires the pilot signal 100, or until the transmission of the transfer amount control signal is completed in the transmission time. The transfer amount control signal 101 is acquired from the control signal queue 310a without acquiring 102 from the data signal queue 320. The control unit 330a transmits the acquired control signal 101 to the subscriber line terminating device 20 during a period from the time when the control signal queue 310a acquires the pilot signal 100 until the transmission time elapses. Accordingly, the subscriber line terminal station apparatus 3a of the first embodiment can transmit the control signal with priority over the data signal.

  In the subscriber line terminal station device 3a of the first embodiment, even when the transfer device 31a has a shared bus for the uplink signal and the downlink signal, the transfer of the uplink signal does not affect the transmission time of the control signal 101. It is possible to do so. When the transfer device 31a has a shared bus for the uplink signal and the downlink signal, the control unit 330a uses the uplink signal for the same period as when the control unit 330a stops acquiring the downlink data signal. The transfer of a certain data signal may be temporarily stopped.

(Second Embodiment)
The second embodiment is different from the first embodiment in that the control unit acquires the control signal based on the interrupt signal. In the second embodiment, only differences from the first embodiment will be described.

  FIG. 3 is a diagram illustrating an example of the configuration of the optical access network 1b. The optical access network 1b is a communication system having an optical fiber as a medium. The optical access network 1b includes a PON 2 and a subscriber line terminal station device 3b. The subscriber line terminal station device 3b includes a bandwidth allocation device 30b and a transfer device 31b.

  The transfer device 31b is a device that transfers a downstream signal to the PON2. The transfer device 31b transfers both a data signal including user data and a control signal such as a transmission permission signal to the PON 2. The transfer device 31b includes a control signal queue 310b, a data signal queue 320, a control unit 330b, a transmission unit 340, and a timer 350.

  The allocation unit 300b is a control signal transmission unit that transmits a control signal. The allocation unit 300b transmits a control signal 101 such as a transmission permission signal to the transfer device 31b. The timing (transmission time) at which the allocation unit 300b transmits the control signal 101 to the control signal queue 310b is determined in advance. For example, the timing at which the allocation unit 300b transmits the control signal 101 to the control signal queue 310b may be a fixed period. The allocation unit 300b may not transmit the pilot signal 100 to the control signal queue 310b.

  The control signal queue 310b acquires the control signal 101 such as a transmission permission signal or an OAM message from the allocation unit 300b. The control signal queue 310b holds the acquired control signal 101. The timer 350 outputs an interrupt signal to the control unit 330b immediately before the time when the allocation unit 300b transmits the control signal 101 to the control signal queue 310b. That is, the timer 350 outputs an interrupt signal to the control unit 330b immediately before the time when the control signal queue 310b acquires the control signal 101.

  The controller 330b acquires an interrupt signal from the timer 350 instead of acquiring the pilot signal 100. The control unit 330b acquires the control signal 101 from the control signal queue 310b without acquiring the data signal from the data signal queue 320 until the transmission time elapses from the time when the interrupt signal is acquired from the timer 350. The control unit 330b controls the control signal 101 for a predetermined time or a predetermined number (transfer amount) without transmitting a data signal to the transmission unit 340 before the transmission time elapses from the time when the interrupt signal is acquired from the timer 350. Is transmitted to the transmission unit 340.

  As described above, the subscriber line terminal station device 3b of the second embodiment includes the bandwidth allocation device 30b and the transfer device 31b. The band allocation device 30b includes an allocation unit 300b as a control signal transmission unit. The transfer device 31b includes a control signal queue 310b, a data signal queue 320, a timer 350, and a control unit 330b. The allocation unit 300b transmits a control signal 101 that is a signal related to the control of the subscriber line terminating device 20. The control signal queue 310b acquires the control signal 101. The data signal queue 320 acquires the data signal 102 transmitted to the subscriber line termination device 20. The timer 350 transmits an interrupt signal at a predetermined time. The control unit 330b ensures the transmission time of the control signal. The controller 330b acquires the control signal from the control signal queue 310b without acquiring the data signal from the data signal queue 320 during the secured transmission time, and transmits the acquired control signal to the subscriber line termination device 20. To do. That is, the control unit 330b transmits the control signal 101 without acquiring the data signal 102 from the data signal queue 320 during the period from when the interrupt signal is transmitted until the transmission time of the control signal 101 elapses. Acquired from 310b. The control unit 330b transmits the acquired control signal 101 to the subscriber line terminating device 20 during a period from when the interrupt signal is transmitted until the transmission time of the control signal 101 elapses. Accordingly, the subscriber line terminal station device 3b according to the second embodiment can transmit the control signal with priority over the data signal.

  Since the control unit 330b does not acquire the pilot signal 100, the subscriber line terminal apparatus 3b of the second embodiment compares the configuration of the control unit 330b of the second embodiment with the configuration of the control unit 330a of the first embodiment. And can be simple. The subscriber line terminal apparatus 3b of the second embodiment is particularly effective when the allocating unit 300a transmits a control signal to the transfer apparatus 31b at a constant period.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  The present invention is applicable to a subscriber line terminal station apparatus of an optical access network.

  DESCRIPTION OF SYMBOLS 1a, 1b ... Optical access network, 2 ... PON, 3a, 3b ... Subscriber line terminal apparatus, 20 ... Subscriber line termination apparatus, 30a, 30b ... Band allocation apparatus, 31a, 31b ... Transfer apparatus, 100 ... Pilot signal DESCRIPTION OF SYMBOLS 101 ... Control signal 102 ... Data signal 300a, 300b ... Allocation part, 310a, 310b ... Control signal queue, 320 ... Data signal queue, 330a, 330b ... Control part, 340 ... Transmission part, 350 ... Timer

Claims (3)

A subscriber line terminal device comprising a bandwidth allocation device and a transfer device,
The bandwidth allocation device
A control signal transmission unit that transmits a control signal that is a signal related to the control of the subscriber line termination device;
The transfer device is
A control signal queue for acquiring the control signal;
A data signal queue for obtaining a data signal transmitted to the subscriber line termination device;
The transmission time of the control signal is ensured, the control signal is acquired from the control signal queue without acquiring the data signal from the data signal queue at the transmission time, and the acquired control signal is added to the subscription And a control unit that transmits to the subscriber line terminating device,
Subscriber line terminal equipment. The control signal transmission unit transmits a pilot signal describing a transmission time and a transfer amount of the control signal, and starts transmission of the control signal at a time when a predetermined standby time has elapsed from the transmission time of the pilot signal. ,
The control signal queue acquires the control signal and the pilot signal,
The control unit is a period until the transmission time elapses from the time when the control signal queue acquires the pilot signal, or a period until the transmission of the transfer amount control signal is completed in the transmission time, 2. The transfer amount control signal is acquired from the control signal queue without acquiring a data signal from the data signal queue, and the acquired control signal is transmitted to the subscriber line terminating device. The subscriber line terminal equipment as described. A timer for transmitting an interrupt signal at a predetermined time;
The control unit transmits the control signal to the control signal queue without acquiring the data signal from the data signal queue for a period from when the interrupt signal is transmitted to when the transmission time of the control signal elapses. The subscriber line terminal station apparatus according to claim 1, wherein the subscriber line terminal station apparatus transmits the acquired control signal to the subscriber line termination apparatus.

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