JP4415778B2 - Relay transmission equipment - Google Patents

Description

  The present invention relates to a relay transmission device that relays a signal transmitted between a station side device and a subscriber side device.

  The conventional relay transmission device constantly monitors the amount of packets received, and when the packet amount exceeds a predetermined threshold, sends a PAUSE packet to the opposite device on the subscriber side in order to limit the bandwidth. The flow control is performed. (For example, refer to Patent Document 1).

JP 2002-353979 (paragraph 0014, FIG. 1)

  However, in the conventional relay transmission apparatus, although the bandwidth can be limited by flow control, the processing load for constantly monitoring the amount of received packets reduces the processing capacity for signal transmission. was there. Furthermore, there is a possibility of causing a decrease in transmission rate and data loss in the built-in buffer.

  An object of the present invention is to provide a relay transmission apparatus that can prevent a decrease in transmission processing capacity by reducing a load for monitoring the amount of transmitted signals.

The present invention comprises a station-facing transceiver unit facing the station-side device and a subscriber-facing transceiver unit facing the subscriber-side device, and a signal transmitted between the station-side device and the subscriber-side device is transmitted. A relay transmission device for relaying,
The station-facing transceiver unit stores an upstream signal to be transmitted from the subscriber-side device to the station-side device after being input from the subscriber-facing transceiver unit and before being transmitted to the station-side device; An accumulation amount monitoring unit for monitoring the accumulation amount of the signal stored in the upstream buffer,
The subscriber-facing transmission / reception unit transfers an upstream input buffer for storing the upstream signal after input, an upstream output buffer for storing the upstream signal before output, and transfers a signal stored in the upstream input buffer to the upstream output buffer. and uplink transfer processing unit that performs a process of, and a flow control unit for transmitting a flow control signal to the subscriber unit based on the accumulated amount of the uplink buffer,
Wherein the flow control unit, after transmitting the flow control signal for starting the flow control, in order to determine whether to stop the flow control, based on the transfer processing status by the uplink transfer processing unit The relay transmission apparatus is characterized in that a storage amount is checked in a storage amount monitoring unit .

  According to the relay transmission apparatus of the present invention, since the accumulated amount is confirmed based on the transfer processing status, it is not necessary to confirm the accumulated amount more than necessary after the flow control is started, and the station facing transmission / reception unit from the subscriber facing transmitting / receiving unit. It is possible to reduce the number of accesses to the subscriber unit and reduce the processing load on the subscriber-facing transceiver unit. For this reason, it is possible to prevent a decrease in transfer processing capability performed by the subscriber-facing transceiver unit, and it is possible to prevent a decrease in transfer rate and data loss.

  FIG. 1 is a diagram showing a network configuration related to the present invention. One station-side device 11 is connected to a plurality of relay transmission devices 13 via a splitter 12 via an optical fiber cable, and each relay transmission device 13 is connected to a subscriber-side device via a LAN (Local Area Network) cable. . The station side device 11 is an ATM (Asynchronous Transfer Mode) transmission device installed in the station of a communication carrier. The splitter 12 is an optical element for branching the optical transmission path into a plurality of parts. The relay transmission device 13 is a device that is installed in a subscriber's house and relays a signal transmitted between the station-side device 11 and the subscriber-side device 14. An ATM cell received from the station-side device 11 is transferred to the Ethernet ( The Ethernet frame is converted into a registered frame and transmitted to the subscriber side device 14, and the Ethernet frame received from the subscriber side device 14 is converted into an ATM cell and transmitted to the station side device 11. The subscriber side device 14 is a device such as a personal computer that is directly operated by the subscriber in the subscriber premises.

  Among these, the station side apparatus 11, the splitter 12, and the relay transmission apparatus 13 constitute a PON (Passive Optical Network) system. In the PON system, the station side device is called an OLT (Optical Line Terminal), and the relay transmission device is called an ONU (Optical Network unit).

<Comparative example>
FIG. 2 is a diagram illustrating an internal configuration of a relay transmission apparatus as a comparative example. The relay transmission apparatus 13 includes a station-facing transmission / reception unit 21 (hereinafter referred to as a general-purpose device 21) configured with a general-purpose device and a subscriber-facing transmission / reception unit 22 (hereinafter referred to as a CPU 22) configured with a CPU (Central Processing Unit). It has.

  The general-purpose device 21 includes a transmission unit 31 incorporating an upstream buffer 32, a reception unit 33 incorporating a downstream buffer 34, a buffer accumulation amount monitoring unit 35, and a grant extraction unit 36. It is the device which transmits and receives between. The upstream buffer 32 is a buffer for temporarily storing the main signal data received from the CPU 22 to the general-purpose device 21 before sending it to the station-side device 11. The transmission unit 31 stores the main signal data received from the CPU 22 in the upstream buffer 32 and then transmits the main signal data to the station-side device 11 based on the grant signal extracted by the grant extraction unit 36. The downlink buffer 34 is a buffer for temporarily storing before receiving the main signal data from the station side device 11 before sending it to the CPU 22. The receiving unit 33 stores the main signal data received from the station side device 11 in the buffer 34 and then sends it to the CPU 22. The buffer accumulation amount monitoring unit 35 is a monitoring unit that monitors the accumulation amount by periodically referring to the main signal data accumulation state of the upstream buffer 32 and detects that the accumulation amount is equal to or greater than the threshold A1. At this time, when the CPU 22 is referred to the interrupt signal via the interrupt notification line and the CPU 22 is referred to the main signal data accumulation amount of the upstream buffer 32 via the buffer accumulation amount read bus, the accumulation amount is returned. .

  The CPU 22 includes a reception unit 41, a transmission unit 45, a flow control processing unit 49, an EA (Ethernet / ATM) conversion unit 51, and an AE (ATM / Ethernet) conversion unit 52. The reception unit 41 includes an upstream input buffer 42, an upstream transfer processing unit 43, and an upstream output buffer 44, and the transmission unit 45 includes a downstream input buffer 46, a downstream transfer processing unit 47, and a downstream output buffer 48. The upstream input buffer 42 is a buffer for temporarily storing main signal data when a main signal is received from the subscriber side device 14. The upstream transfer processing unit 43 is a transfer processing unit for transferring main signal data. The upstream output buffer 44 is a buffer for temporarily storing main signal data from the CPU 22 to the general-purpose device 21. When the flow control processing unit 49 receives an interrupt signal from the general-purpose device 21, the flow control processing unit 49 transmits a flow control start signal to the subscriber side device 14, and the main signal in the general-purpose device 21 via the accumulation amount read bus. It is a processing unit that periodically refers to the data accumulation amount and performs a process of transmitting a flow control stop signal when it is detected that the amount is equal to or less than a predetermined threshold A2. The downlink output buffer 48 is a buffer for temporarily storing the main signal data from the station side device 11 to the subscriber side device 14 before sending the main signal data to the subscriber side device 14. The downlink transfer processing unit 47 is a transfer processing unit for transferring main signal data. The downlink input buffer 46 is a buffer for temporarily storing data when main signal data is received from the general-purpose device 21. The EA conversion unit 51 is a conversion unit that converts an Ethernet frame into an ATM cell, and the AE conversion unit 52 is a conversion unit that converts an ATM cell into an Ethernet frame.

  FIG. 3 is a diagram illustrating a software processing flow in the comparative example. When the process is started, it is an interrupt reception waiting process for receiving an interrupt signal via the interrupt notification line from the general-purpose device 21 in step a1. In the next step a2, it is determined whether or not an interrupt signal has been received. Steps a1 and a2 are repeated until the interrupt signal is received, and the subsequent processing does not operate. When the interrupt signal is received, the process proceeds to the next step a3, and a flow control signal transmission process for transmitting a flow control signal to the subscriber side device 14 is executed. Next, in step a4, a timer setting process is performed as preparation for performing the flow control stop determination. A fixed value such as a pause frame transmission time is used as the timer value t1. Next, in step a5, it is determined whether or not the timer value t1 has expired. Next, in step a6, processing for referring to the main signal data storage amount of the upstream buffer 33 via the storage amount read bus is performed. Next, in step a7, a process for comparing the stored accumulation amount data with the threshold value A2 held in the CPU 22 is performed. As a result of the comparison, when the read accumulation amount exceeds the threshold value A2, the process returns to the timer setting in step a4 again, and the processes in steps a4 to a7 are repeated. When the read accumulation amount is equal to or less than the threshold value A2, the subsequent processing is performed. In step a8, a process of transmitting a flow control stop signal to the subscriber side device 14 is performed, and the process returns to the interrupt reception waiting process in step a1.

  Problems in the comparative example will be described. Since the timer value is the fixed value t1 when the timer is set in step a4 in FIG. 3, when the flow control process is performed, a steady load is generated in the CPU 22, and the uplink transfer process in FIG. The processing capability of the unit 43 and the downlink transfer processing unit 47 is reduced. As a result, there is a problem in that the main signal transfer rate in the bidirectional direction from the subscriber side device 14 to the station side device 11 and the downstream direction from the station side device 11 to the subscriber unit 14 is lowered. Further, as a secondary influence, when the processing capacity is reduced in the transfer processing units 43 and 47, when the main signal input from the subscriber side device 14 or the general-purpose device 21 is large, the upstream input buffer 42 or buffer of FIG. The main signal data stored in 46 overflows from the buffer, and main signal data is lost.

<Embodiment>
FIG. 4 is a diagram showing an internal configuration of the relay transmission apparatus according to the embodiment of the present invention. The configuration in FIG. 4 is substantially the same as that in FIG. 2, so the same components are denoted by the same reference numerals and description thereof is omitted. Hereinafter, differences from FIG. 2 will be described. The upstream transfer processing unit 43 is provided with an input / output interface with the flow control processing unit 49. Further, the transfer processing unit 47 is provided with an output interface to the flow control processing unit 49. Further, the flow control processing unit 49 is provided with a function capable of stopping or canceling the stop of the main signal data input from the general-purpose device 21 by instructing the AE conversion unit 52. Further, the flow control processing unit 49 is classified into three functions A, B, and C. The function A is triggered by an interrupt notification line from the general-purpose device 21, and the function B is an upstream transfer process. It is assumed that the operation is triggered by the notification from the unit 43, and the function C is triggered by the notification from the downlink transfer processing unit 47.

  The operation using this configuration will be described with reference to FIG.

  First, a process for improving the process of performing the flow control by the interrupt notified when the main signal data accumulation amount exceeds the threshold value A1 from the general-purpose device 21 will be described with reference to FIGS.

  FIG. 5 is a diagram illustrating a processing flow of the function A by the flow control processing unit. In step b1, reception of an interrupt signal from the general-purpose device 21 via the interrupt notification line is awaited. This is the same processing as step a1 in FIG. Next, in step b2, it is determined whether an interrupt signal has been received. This is the same processing as step a2 in FIG. Next, in step b3, a flow control start signal is transmitted to the subscriber side apparatus 11. This is the same processing as step a3 in FIG. In step b4, the upstream transfer processing unit 43 in FIG. 4 is notified that the flow control has started. Next, in step b5, a notification for determining flow control stop is received from the uplink transfer processing unit 43 in FIG. Next, in step b6, a process of reading the main signal data amount stored in the upstream buffer 32 of FIG. 4 from the general-purpose device 21 via the buffer storage amount read bus is performed. Next, in step b7, the read buffer accumulation amount is compared with the threshold value A2, and when the buffer accumulation amount exceeds the threshold value A2, the process returns to step b3 and is processed again. On the other hand, if the buffer accumulation amount is equal to or smaller than the threshold A2, the process proceeds to the next step b8. In step b8, a process for transmitting a flow control stop signal to the subscriber side apparatus is performed, and the process returns to the interrupt reception waiting process in step b1. This is the same processing as step a8 in FIG.

  FIG. 6 is a diagram illustrating a processing flow of the uplink transfer processing unit associated with function A. In step c1, a request reception waiting process is performed. At this time, the flow control request received from the function A of the flow control processing unit 49 and the transfer request transmitted to itself by the upstream transfer processing unit 43 can be received. Next, in step c2, the received request is analyzed. If a flow control request is received, the process proceeds to the next step c3. If a transfer request is received, the process of step c5 is performed. In step c3, a counter (n) for determining a trigger for notifying the flow control processing unit 49 of the flow control stop determination is calculated and stored in the CPU 22. The counter (n) is calculated from the number of difference data between the threshold value A1 and the threshold value A2. Next, in step c4, the uplink transfer processing unit 43 transmits a transfer request to itself. On the other hand, in step c5, the same main signal transfer process as that described later with reference to FIG. 8 is executed. Next, in step c6, when the main signal transfer is completed, the set counter (n) is decremented. Next, in step c7, when the counter (n) becomes 0, the process proceeds to the next step c8, and when it is not 0, step c4 is executed. In step c8, the flow control processing unit 49 is notified of a flow control stop determination request.

  The processing load on the CPU 22 can be reduced by setting an appropriate timer value based on the difference between the counter check and the excess / cancellation threshold value in the processes of FIGS.

  Next, when the transfer processing capacity is reduced due to a secondary effect, the main signal data is accumulated in the upstream input buffer 42 from the subscriber side device 14 and is therefore improved. The points will be described with reference to FIGS. This is intended to improve by performing flow control when the upstream transfer processing unit 43 detects that the main signal data storage amount stored in the upstream input buffer 42 exceeds the threshold value B1.

  FIG. 7 is a diagram illustrating a processing flow of the function B by the flow control processing unit. In step d1, reception waiting processing of the flow control start notification from the uplink transfer processing unit 43 is performed. Next, in step d2, a process of transmitting a flow control signal to the subscriber side device 14 is performed. This is the same processing as step a3 in FIG. Next, in step d3, processing for setting a timer (t2) until the flow control is stopped is performed. Next, in step d4, a timeout is determined. If it is not a timeout, the process of step d4 is repeatedly executed until the timeout occurs. When it is time-out, in the next step d5, a process of transmitting a flow control stop signal is performed, and the process returns to step d1.

  FIG. 8 is a diagram illustrating a processing flow of the uplink transfer processing unit associated with function B. In step e1, the accumulated amount of the upstream input buffer 42 is compared with the threshold value B1, and if the threshold value is exceeded, the process proceeds to the next step e2. If the threshold is not exceeded, step e2 is skipped and the process proceeds to step e3. In step e2, a process for notifying the function B of the flow control processing unit 49 to execute the flow control is performed. In step e3, the data stored in the upstream input buffer 42 is transferred to the upstream output buffer 44, and the processing in FIG.

  7 and 8, main signal data is not accumulated beyond the threshold B1 of the upstream input buffer 42, and overflow does not occur, so that data loss can be prevented.

  Next, when the transfer processing capacity is reduced due to the secondary influence of the conventional technique, the main signal data is accumulated in the downlink input buffer 46 from the station side apparatus 11 and thus overflows. The point will be described mainly with reference to FIGS. 9 and 10.

  First, processing related to flow control will be described. When the main signal data accumulation amount accumulated in the downlink input buffer 46 exceeds the threshold value C1, the downlink transfer processing unit 47 detects this and notifies the flow control processing unit 49 (step g2 in FIG. 10). If the threshold value C2 is not reached, the downlink transfer processing unit 47 detects this and notifies the flow control processing unit 49 (step g5 in FIG. 10). The flow control processing unit 49 starts and stops the flow control according to the notification content from the downlink transfer processing unit 47.

  Next, the main signal stop process will be described with reference to FIGS. 9 and 10.

  FIG. 9 is a diagram illustrating a processing flow of the function C by the flow control processing unit. In step f1, a process of waiting for reception of a signal for notifying flow control stop or flow control restart from the downlink transfer processing unit 47 is performed. Next, in step f2, the received notification is analyzed. If the received notification is a stop notification, the process of the next step f3 is executed, and if it is a restart notification, the process of step f4 is executed. In step f3, the AE conversion unit 52 is instructed to perform processing for stopping the main signal data input port from the general-purpose device 21 to the CPU 22. In step f4, the AE conversion unit 52 is instructed to perform a process of restarting the stop of the main signal data input from the general-purpose device 21 to the CPU 22.

  FIG. 10 is a diagram illustrating a processing flow of the downlink transfer processing unit associated with the function C. In step g1, the amount stored in the downstream input buffer 46 is compared with the threshold C1, and if the threshold is exceeded, the process proceeds to the next step g2. If the threshold is not exceeded, the process proceeds to step g4. In step g2, a process for notifying the flow control processing unit 47 of a stop request is performed. This stop request is transmitted only when the previous notification is a restart request. Next, in step g3, a process of transferring the data stored in the downlink input buffer 46 to the downlink output buffer 48 is performed. In step g4, the amount stored in the downlink input buffer 46 is compared with the threshold C2, and if the threshold is not exceeded, the process proceeds to the next step g5. When the threshold value is exceeded, step g5 is skipped and the process proceeds to step g3. In step g5, a process for notifying the flow control processing unit 47 of a restart request is performed. This restart request is transmitted only when the previous notification is a stop request. When the process of step g3 is completed, the process returns to step g1, and the process of FIG. 10 is repeated.

  9 and 10 and the like, the main signal data is not accumulated beyond the threshold C1 of the downlink input buffer 46, and no overflow occurs, so that data loss can be prevented. . Further, in step g2 and step g5 in FIG. 10, since it is possible to obtain the minimum required notification and stop notification by comparing with the previously transmitted state, it is possible to reduce the wasteful load on the CPU 22 and wasteful flow control. There is also an effect that does not occur.

  As described above, according to the present embodiment, the CPU processing load during flow control can be reduced, and the transfer capability of processing for performing main signal transfer can be relatively improved. In addition, in order not to cause buffer overflow, main signal data is not lost even when the CPU load increases. Therefore, the CPU is not a high-function, high-price CPU capable of withstanding bursty main signal input. However, a sufficient level of function can be realized with a CPU having a level capable of withstanding regular processing capability.

It is a figure which shows the network structure relevant to this invention. It is a figure which shows the internal structure of a relay transmission apparatus as a comparative example. It is a figure which shows the software processing flow in a comparative example. It is a figure which shows the internal structure of the relay transmission apparatus which concerns on embodiment of this invention. It is a figure which shows the processing flow of the function A by a flow control process part. It is a figure which shows the processing flow of the uplink transmission process part accompanying the function A. FIG. It is a figure which shows the processing flow of the function B by a flow control process part. 7 is a diagram illustrating a processing flow of an uplink transfer processing unit according to function B. FIG. It is a figure which shows the processing flow of the function C by a flow control process part. 7 is a diagram illustrating a processing flow of a downlink transfer processing unit according to function C. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Station side apparatus 12 Splitter 13 Relay transmission apparatus 14 Subscriber side apparatus 21 Station opposing transmission / reception part (general-purpose device)
22 Subscriber-facing transceiver (CPU)
31 Transmission Unit 32 Upstream Buffer 33 Reception Unit 34 Downstream Buffer 35 Buffer Accumulation Monitor Unit 36 Grant Extraction Unit 41 Reception Unit 42 Upstream Input Buffer 43 Upstream Transfer Processing Unit 44 Upstream Output Buffer 45 Transmitter 46 Downstream Input Buffer 47 Downstream Transfer Processing Unit 48 Downstream output buffer 49 Flow control processing unit 51 EA conversion unit 52 AE conversion unit A, B, C Each function (of flow control processing unit) A1, A2, B1, B2, C1, C2 Each threshold value

Claims (4)

A relay transmission that relays a signal transmitted between the station-side device and the subscriber-side device, comprising a station-facing transmitter-receiver that faces the station-side device and a subscriber-facing transceiver that faces the subscriber-side device A device,
The station-facing transceiver unit stores an upstream signal to be transmitted from the subscriber-side device to the station-side device after being input from the subscriber-facing transceiver unit and before being transmitted to the station-side device; An accumulation amount monitoring unit for monitoring the accumulation amount of the signal stored in the upstream buffer,
The subscriber-facing transmission / reception unit transfers an upstream input buffer for storing the upstream signal after input, an upstream output buffer for storing the upstream signal before output, and transfers a signal stored in the upstream input buffer to the upstream output buffer. and uplink transfer processing unit that performs a process of, and a flow control unit for transmitting a flow control signal to the subscriber unit based on the accumulated amount of the uplink buffer,
Wherein the flow control unit, after transmitting the flow control signal for starting the flow control, in order to determine whether to stop the flow control, based on the transfer processing status by the uplink transfer processing unit A relay transmission apparatus characterized in that an accumulation amount is checked in an accumulation amount monitoring unit . The relay transmission apparatus according to claim 1, wherein the transfer processing status in the uplink transfer processing unit is represented by a total amount of signals transferred after transmitting a flow control signal for starting flow control. The flow control unit further has a function of monitoring the accumulation amount of the signal stored in the uplink input buffer and transmitting a flow control signal for starting flow control based on the accumulation amount of the uplink input buffer. The relay transmission apparatus according to claim 1. The subscriber-facing transceiver unit includes a downlink input buffer that stores a downlink signal to be transmitted from the station side device to the subscriber side device after input, a downlink output buffer that stores the downlink signal before output, A downlink transfer processing unit that performs processing for transferring the signal stored in the downlink input buffer to the downlink output buffer ;
The flow control processing unit monitors the accumulation amount of the signal stored in the downlink input buffer, and based on the accumulation amount of the downlink input buffer, a flow related to the input from the station facing transceiver unit to the downlink input buffer The relay transmission apparatus according to claim 1 , further comprising a function of starting and stopping control .

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