JP5541806B2 - COMMUNICATION SYSTEM AND TERMINAL DEVICE - Google Patents

Description

  The present invention relates to a communication system and a termination device.

  2. Description of the Related Art Conventionally, with the broadbandization of the Internet, large-capacity data transmission has been required even in ordinary homes, and communication systems such as PON (Passive Optical Network) systems using optical fibers have been developed.

  For example, each of a plurality of ONUs (Optical Network Units) monitors a data flow rate, notifies the OLT (Optical Line Terminal) of the flow rate monitoring result, and a plurality of ONUs generated by the OLT based on the flow rate monitoring result. There is a technology that receives control information for controlling the increase / decrease of the transmission band to be allocated to each and realizes fine band control in units of queues, and effectively uses the transmission section band (see, for example, Patent Document 1).

JP 2007-19647 A

  However, in the prior art, when excessive data flows into the transmission band allocated to the ONU, the excessive band data is discarded, so that the data from the beginning or the data from the untransmitted part is again OLT. There is a problem that it has to be sent back to.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, an object of the present invention is to provide a technique that can transmit data with high accuracy without retransmitting data.

One aspect of a communication system exemplifying the present invention is a communication comprising a plurality of terminal devices each accommodating a user terminal, and a termination device arranged on the network and controlling data transmission between the plurality of terminal devices and the network. In the system, the terminal device acquires the storage capacity of the storage unit included in the terminal device and the untransmitted data amount stored in the storage unit from the data received from the user terminal from the terminal device, and the acquired storage capacity Based on the estimated time until the storage unit calculated from the difference from the untransmitted data amount and the communication speed between the terminal device and the accommodated user terminal is filled with untransmitted data, to the terminal device for the terminal device A data transmission bandwidth allocation process and a control unit for controlling the time interval of the allocation process.

  Moreover, a control part may control the order of the data transmission to the termination | terminus apparatus by a some terminal device based on a difference or prediction time.

  Further, the control unit may control the time interval according to the number of terminal devices.

  Further, the terminal device may perform data transmission with the terminal device at a communication speed different from that of other terminal devices.

One aspect of the termination device exemplifying the present invention is a termination device which is arranged on a network and controls data transmission between a plurality of terminal devices each accommodating a user terminal and the network, and the storage included in the terminal device Of the data received from the user terminal and the amount of untransmitted data stored in the storage unit from the terminal device, and the difference between the acquired storage capacity and the amount of untransmitted data and the terminal device Based on the estimated time until the storage unit calculated from the communication speed with the user terminal is filled with untransmitted data, bandwidth allocation processing of data transmission to the terminal device to the terminal device , and time of allocation processing A control unit for controlling the interval is provided.

  According to the present invention, data can be transmitted with high accuracy without being retransmitted.

1 is a block diagram showing a configuration of a network system according to an embodiment. Block diagram showing the configuration of ONU Block diagram showing the configuration of OLT The flowchart which shows the communication operation by the GE-PON system which concerns on one Embodiment. The figure which shows an example of the specification and untransmitted frame length of each ONU

  FIG. 1 is a block diagram showing a configuration of a network system according to an embodiment of the present invention.

  In the network system shown in FIG. 1, a network device such as a terminal 1a or a server 1b is arranged above the network 2, and a GE-PON formed using Gigabit Ethernet (GE) (Ethernet is a registered trademark) below the network 2. Deploy the system.

  The GE-PON system is an OLT 3, an optical splitter 4 that splits an optical signal into a plurality of parts using a splitter of passive elements, ONUs 5-1 to 5-N, and ONUs 5-1 to 5-N, respectively, as a communication system of this embodiment. Are connected to user terminals 6-1 to 6-N (N is a natural number). The OLT 3 and the optical coupler 4 and the optical coupler 4 and the ONUs 5-1 to 5-N are connected by optical fibers, respectively. In the GE-PON system of the present embodiment, downstream communication from the OLT 3 to the ONUs 5-1 to 5-N is performed based on, for example, time division multiplexing (TDMA) using an optical signal having a wavelength of 1.5 μm, Uplink communication from the ONUs 5-1 to 5-N to the OLT 3 is performed based on, for example, a burst method using an optical signal having a wavelength of 1.3 μm.

  In FIG. 1, the network devices of the two terminals 1a and the server 1b are arranged above the network 2, but three or more network devices may be connected. The user terminals 6-1 to 6-N are general personal computers, portable terminals, and the like.

  Next, FIG. 2 is a block diagram showing the configuration of the ONU 5-k that is a terminal device according to the present embodiment (1 ≦ k ≦ N). As illustrated in FIG. 2, the ONU 5-k includes a UNI (User Network Interface) 10, a MAC chip 11, a buffer memory 12, a GE-PON termination unit 13, and a buffer memory 14.

  The UNI 10 is an interface that is connected to the user terminal 6-k and transmits / receives data to / from the user terminal 6-k. Data transmission / reception between the UNI 10 and the user terminal 6-k is set based on communication between the user terminal 6-k and the MAC chip 11 when the user terminal 6-k is first connected to the UNI 10. Done at link speed. It is assumed that the UNI 10 according to this embodiment conforms to the UNI PHY including a 10 gigabit Ethernet LAN / WAN PHY defined by IEEE 802.3ae. Moreover, although UNI10 shown in FIG. 2 is connected to only one user terminal 6-k, a plurality of user terminals may be connected.

  The MAC chip 11 is a microprocessor that performs MAC control of each unit of the ONU 5-k. Further, the MAC chip 11 collects information such as predetermined statistical information (error information and the like), storage capacity of buffer memories 12 and 14 described later, and the amount of untransmitted data based on the MAC control. At the same time, as shown in FIG. 2, the MAC chip 11 operates as a reception frame processing unit 15 and a transmission frame processing unit 18 in the downlink direction as a reception frame processing unit 15 and a transmission frame processing unit 16 in the upstream direction.

  The reception frame processing unit 15 receives an Ethernet frame of data transmitted from the user terminal 6 -k via the UNI 10. The reception frame processing unit 15 checks for errors in the received Ethernet frame and temporarily stores data in the buffer memory 12. The buffer memory 12 is a volatile semiconductor memory or the like.

  As will be described later, the transmission frame processing unit 16 sequentially reads the data from the user terminal 6-k stored in the buffer memory 12 based on the band allocation set by the control instruction from the OLT 3, and the GE- Output as an Ethernet frame to the PON termination unit 13.

  The reception frame processing unit 17 receives an Ethernet frame addressed to the user terminal 6 -k transmitted from the terminal 1 a or the server 1 b arranged on the upper side of the network 2 via the GE-PON termination unit 13. Similarly to the case of the reception frame processing unit 15, the reception frame processing unit 17 checks for errors and the like in the received Ethernet frame and temporarily accumulates data in the buffer memory 14. The buffer memory 14 is a volatile semiconductor memory or the like, similar to the buffer memory 12. In this embodiment, two buffer memories 12 and 14 are used. However, one buffer memory may be used as two buffer memories 12 and 14 by setting an area.

  The transmission frame processing unit 18 sequentially reads data stored in the buffer memory 14 based on a control instruction from the MAC chip 11 and transmits the data to the user terminal 6-k as an Ethernet frame.

  The GE-PON termination unit 13 receives an Ethernet frame optical signal transmitted from the OLT 3 by the TDMA method, or transmits an Ethernet frame having data from the user terminal 6-k to the OLT 3 as a burst signal. It is. The GE-PON termination unit 13 of the present embodiment includes an optical-electric conversion unit (not shown) that converts an Ethernet frame transmitted by the ONU itself into a burst signal and an optical signal from the OLT 3 into an electrical signal.

  FIG. 3 is a block diagram illustrating a configuration of the OLT 3 that is a termination device according to the present embodiment. As shown in FIG. 3, the OLT 3 includes a GE-PON termination unit 20, a control unit 21, and an SNI (Service Node Interface) 22.

  The GE-PON terminator 20 is an interface that transmits optical signals to the ONUs 5-1 to 5-N by the TDMA method and receives burst signals from the ONUs 5-1 to 5-N. Similar to the GE-PON termination unit 13, the GE-PON termination unit 20 of the present embodiment converts burst signals from the ONUs 5-1 to 5-N into electrical signals, and converts an Ethernet frame transmitted by the OLT 3 into optical signals. A photoelectric conversion unit (not shown).

  The control unit 21 is a microprocessor such as a MAC chip that comprehensively controls the operation of each unit of the OLT 3. In the present embodiment, as will be described later, the control unit 21 executes the control program to transmit untransmitted data accumulated in the buffer memory 12 from each of the ONUs 5-1 to 5-N at predetermined time intervals. Get information such as quantity. Based on the acquired information, the control unit 21 performs DBA (Dynamic Bandwidth Allocation) processing for allocating a bandwidth at the time of transmission to each of the ONUs 5-1 to 5-N. In the present embodiment, it is assumed that the predetermined time interval (hereinafter referred to as DBA cycle) is preset to 600 μsec. However, as will be described later, the length of the DBA cycle can be changed according to the amount of untransmitted data stored in the buffer memory 12, and is appropriately determined according to the configuration of the GE-PON system and the OLT 3. It is preferable.

  The SNI 22 is an interface that transmits and receives data between the network 2 and the OLT 3.

  Next, a communication operation in the GE-PON system according to the present embodiment, particularly an upstream communication operation from the ONUs 5-1 to 5-N to the OLT 3 in the GE-PON system will be described with reference to the flowchart of FIG. .

  In the present embodiment, as shown in FIG. 5, the number of ONUs 5 is N = 5, but the same communication operation is performed even in other numbers. FIG. 5A shows an example of the specifications of the ONUs 5-1 to 5-5 in this embodiment and the untransmitted frame length at a certain point in time. Based on the information shown in FIG. 5A, the OLT 3 performs DBA processing and allocates bandwidth to each of the ONUs 5-1 to 5-5. Here, the PON line communication speed indicates a communication speed between the OLT 3 and the ONU 5-k. In the GE-PON system of the present embodiment, two communication speeds of 1 Gbps and 10 Gbps are mixed. The queue capacity is the storage capacity of the buffer memory 12 in the upstream direction, and the untransmitted frame length is the untransmitted data stored in the buffer memory 12 among the data received from the accommodated user terminal 6-k. The UNI link speed indicates a communication speed between the ONU 5-k and the user terminal 6-k.

  Furthermore, the presence / absence of flow control means that the UNI 10 of the ONU 5-k regulates data transmission to the user terminal 6-k accommodated when the untransmitted frame length accumulated in the buffer memory 12 exceeds a predetermined threshold. It shows whether or not it has a known flow control function. In the present embodiment, it is assumed that only the UNI 10 of the ONU 5-5 has no flow control function. Note that the user terminals 6-1 to 6-5 can support the flow control function.

  In addition, the OLT 3 is configured such that at least the PON line communication speed and the queue capacity among the information shown in FIG. 5A regarding the ONUs 5-1 to 5-5 at the time when each of the ONUs 5-1 to 5-5 is first connected. It is assumed that information such as UNI link speed and flow control presence / absence is acquired and stored in a memory (not shown).

  Step S101: The control unit 21 of the OLT 3 acquires the untransmitted frame length stored in the buffer memory 12 of each of the ONUs 5-1 to 5-5. For this purpose, the control unit 21 generates an Ethernet frame with an LLID (logical link ID) identifier addressed to each ONU 5 and transmits it to the ONUs 5-1 to 5-5. The control unit 21 receives the Ethernet frame, which is a report frame, from the ONUs 5-1 to 5-5, and acquires the untransmitted frame length in the ONUs 5-1 to 5-5. At the same time, the control unit 21 preferably generates and transmits an Ethernet frame (discovery GATE frame) with a broadcast LLID for determining whether or not a new ONU is connected.

  Step S102: The control unit 21 determines the presence / absence of untransmitted data based on the untransmitted frame length of the ONUs 5-1 to 5-5 acquired in Step S101. When there is no untransmitted data in the ONUs 5-1 to 5-5, the control unit 21 proceeds to step S101 (NO side). On the other hand, if there is untransmitted data in any ONU 5-k, the control unit 21 proceeds to step S103 (YES side).

Step S103: When the control unit 21 continues to receive data from the user terminal 6-k at the UNI link speed shown in FIG. 5A in order to allocate a bandwidth to the ONU 5-k based on the DBA process, the ONU 5 The time t _k until the untransmitted frame length becomes equal to or greater than the queue capacity at −k is calculated using the following equation (1).
Time t _k = (queue capacity−untransmitted frame length) / (UNI link speed) (1)
FIG. 5B shows an estimated value of the untransmitted frame length in the ONU 5-k after 1 DBA cycle (= 600 μsec) when an Ethernet frame of data is received at the UNI link speed. That is, when the UNI link speed is 10 Gbps, the untransmitted frame length increases by 6 Mbytes every 1 DBA cycle. For example, the queue capacity of the ONU 5-4 is filled with the untransmitted frame length, and the ONU 5-5 overflows. To show that On the other hand, the ONUs 5-1 to 5-3 indicate that the queue capacity still has a sufficient margin.

Step S104: The control unit 21 determines whether there is an ONU 5-k that causes a queue overflow in one DBA cycle based on the time t _k calculated in step S103. When there is an ONU 5-k that causes a queue overflow, the control unit 21 proceeds to step S105 (YES side), and when there is no ONU 5-k that causes a queue overflow, the control unit 21 proceeds to step S109 (NO side).

  Step S105: The control unit 21 allocates a band to preferentially transmit untransmitted data to the ONU 5-5 that is predicted to cause a queue overflow. At the same time, the control unit 21 changes and sets the length of one DBA cycle to the shortest length such as 400 μsec. That is, the control unit 21 preferentially transmits untransmitted data to the ONU 5-5 in the shortest DBA cycle, thereby avoiding queue overflow.

  On the other hand, since the untransmitted frame length of the ONU 5-4 becomes equal to the queue capacity in the next DBA cycle, the control unit 21 gives priority to the untransmitted data to the ONU 5-4 together with the ONU 5-5. Bands may be allocated so as to be transmitted. Alternatively, since the ONU 5-4 has a flow control function, the control unit 21 determines that flow control is performed between the UNI 10 of the ONU 5-4 and the user terminal 6-4. , Bandwidth allocation similar to ONUs other than the ONU 5-5 may be performed.

  Further, in the case shown in FIG. 5, the control unit 21 preferably allocates a smaller bandwidth to the ONUs 5-1 and 5-2 than the ONU 5-5 and the ONU 5-4. Further, since the ONU 5-3 has an untransmitted frame length of 0 bytes, the control unit 21 determines that there is no data transmission / reception between the ONU 5-3 and the user terminal 6-3. It is preferable to allocate a bandwidth for only the report frame.

  Note that the length of the shortest DBA cycle is preferably determined as appropriate based on the configuration of the GE-PON system, the processing capability of the OLT 3, and the like.

  Step S106: The control unit 21 changes the transmission order of the ONUs 5-1 to 5-5 in order to more effectively avoid the queue overflow. For example, the control unit 21 normally transmits burst signals of Ethernet frames in the order of ONU 5-1 to ONU 5-5, but if a queue overflow is predicted, ONU 5-5, ONU 5-4, ONU 5-5 1 and ONU5-2, ONU5-3, etc., are set in such a manner that they are exchanged in this order.

  Step S107: Based on the bandwidth of ONU5-1 to ONU5-5, the length of the DBA cycle, the order of transmission, etc., set in step S105 and step S106, or step S109 and step S110, which will be described later, in step S107. , Ethernet frames that are GATE frames addressed to ONU 5-1 to ONU 5-5 are generated and transmitted. Note that the control unit 21 may simultaneously generate and transmit a discovery GATE frame for determining whether or not a new ONU is connected.

  Step S108: The GE-PON terminator 13 of the ONU 5-1 to ONU 5-5 receives the GATE frame addressed to itself from the OLT 3. The MAC chip 11 sets the transmission band and timing of data and report frames based on the received GATE frame. The transmission frame processing unit 16 reads an amount of data corresponding to the set bandwidth from the buffer memory 12. The GE-PON terminator 13 transmits the Ethernet frame of the read data to the OLT 3 as a burst signal together with the report frame. The control unit 21 of the OLT 3 receives Ethernet frames of data from the ONUs 5-1 to ONU 5-5 via the GE-PON termination unit 20 and via the SNI 22 the terminal 1a arranged at the upper level of the network 2 Or to the server 1b or the like.

  Then, the control unit 21 proceeds to step S101, and performs processing of the next DBA cycle based on the received new report frame until an operation end instruction of the OLT 3 due to maintenance or the like is received from the outside.

  Step S109: The control unit 21 determines whether or not the number N of ONUs 5 has increased or decreased because a new ONU 5 is connected to the OLT 3 or any of the ONUs 5-1 to 5-5 is disconnected. When the number N of ONUs 5 increases or decreases, the control unit 21 proceeds to step S110 (YES side). On the other hand, if the number N of ONUs 5 does not change, the control unit 21 proceeds to step S107 and is based on the bandwidth of the ONUs 5-1 to 5-5, the length of the DBA cycle, the order of transmission, etc. set so far. Then, GATE frames addressed to the ONUs 5-1 to 5-5 are generated and transmitted.

  The increase / decrease in the ONUs 5 connected to the OLT 3 is based on the response signal from the newly connected ONU 5 to the discovery GATE frame transmitted in Step S101 or Step S107, or the report frame received in Step S102 or Step S108. Judgment.

  Step S110: The control unit 21 controls and sets the length of one DBA cycle according to the number N of ONUs 5 connected to the OLT 3. For example, when the control unit 21 uses two threshold values α and β (α and β are natural numbers, α <β) for the number N of ONUs 5 and the number N of ONUs 5 is equal to or less than the threshold value α, the length of the DBA cycle The length is set as long as 700 μsec. When the number N of ONUs 5 is α <N ≦ β, the control unit 21 sets the length of the DBA cycle to 600 μs, and when the number N is larger than the threshold β, the control unit 21 sets the DBA cycle to 500 μs. Then, the control unit 21 proceeds to step S107, and generates and transmits a GATE frame addressed to each ONU 5 based on the newly set DBA cycle length. As a result, by setting the length of the DBA cycle according to the number N of ONUs 5 connected to the OLT 3, the degree of freedom in allocating bandwidth to each ONU 5 is increased and efficient while avoiding queue overflow. The data from the user terminal 6 can be transmitted to the OLT 3.

  Note that the length of the DBA cycle corresponding to the number of thresholds and the number N of ONUs 5 is preferably determined as appropriate based on the configuration of the GE-PON system, the processing capability of the OLT 3, and the like.

  As described above, in this embodiment, the control unit 21 of the OLT 3 overflows the queue within one DBA cycle based on the queue capacity, the untransmitted frame length, the UNI link speed, and the like of each of the connected ONUs 5-1 to 5-5. By predicting whether or not there is an ONU 5-k that causes the ONU 5-k, and setting the DBA cycle length to the shortest, even if the ONU 5-k does not have a flow control function, the ONU 5-k queue overflows. While avoiding this, data can be transmitted with high accuracy without being retransmitted.

  Further, the control unit 21 can transmit data more efficiently and with high accuracy by changing the length of the DBA cycle to the shortest and changing the order of transmission of each ONU 5 based on the prediction. it can.

Further, when there is no ONU 5-k that causes a queue overflow in one DBA cycle, the control unit 21 controls the length of the DBA cycle according to the number N of connected ONUs 5, for example, from each ONU 5. The ratio of the burst header in the transmission bandwidth of 1 DBA cycle in the burst signal can be relatively reduced, and data can be transmitted more efficiently.
<< Additional items of embodiment >>
In the above embodiment, only the ONU 5-5 has no flow control function. However, the present invention is not limited to this, and all the ONUs 5-1 to 5-5 may not have the flow control function. . Further, the present invention can be applied even when the UNI 10 of the ONU 5-k has a flow control function and the user terminal 6-k connected thereto does not support flow control.

  When two or more ONUs 5 are predicted to cause a queue overflow, the control unit 21 may allocate a bandwidth so that the predicted ONUs 5 transmit data preferentially according to the queue overflow amount. preferable.

  In the above embodiment, the PON line communication speed between each of the ONU 5-1 to ONU 5-5 and the OLT 3 is mixed with 1 Gbps and 10 Gbps. However, the present invention is not limited to this, and a single Gbps such as 1 Gbps or 10 Gbps is used. One PON line communication speed may be used.

  In the above embodiment, the queue capacities of the ONUs 5-1 to 5-5 are all 125 Mbytes. However, the present invention is not limited to this, and the queue capacities of the ONUs 5-k depend on the specifications of the ONUs 5-k, the usage environment, and the like. Therefore, it is preferable to determine appropriately.

  From the above detailed description, features and advantages of the embodiments will become apparent. It is intended that the scope of the claims extend to the features and advantages of the embodiments as described above without departing from the spirit and scope of the right. Further, any person having ordinary knowledge in the technical field should be able to easily come up with any improvements and modifications, and there is no intention to limit the scope of the embodiments having the invention to those described above. It is also possible to use appropriate improvements and equivalents within the scope disclosed in.

1a terminal, 1b server, 2 network, 3 OLT, 4 optical splitter, 5-1 to 5-N ONU, 6-1 to 6-N user terminal, 10 UNI, 11 MAC chip, 12, 14 buffer memory, 13, 20 GE-PON termination unit, 15, 17, received frame processing unit, 16, 18 transmission frame processing unit, 21 control unit, 22 SNI

Claims (5)

A communication system comprising a plurality of terminal devices each accommodating a user terminal and a termination device arranged on a network and controlling data transmission between the plurality of terminal devices and the network,
The terminator is
The storage capacity of the storage unit of the terminal device and the amount of untransmitted data stored in the storage unit among the data received from the user terminal are acquired from the terminal device, and the acquired storage capacity and the untransmitted data are acquired . Based on the estimated time until the storage unit calculated from the difference between the amount of data and the communication speed between the terminal device and the user terminal accommodated with the untransmitted data, the terminal device A communication system comprising: a bandwidth allocation process for data transmission to a termination device ; and a control unit that controls a time interval of the allocation process. The communication system according to claim 1,
The said control part controls the order of the data transmission by the said several terminal device to the said termination | terminus apparatus based on the said difference or the said estimated time . The communication system according to claim 1 or 2,
The control unit controls the time interval according to the number of the plurality of terminal devices . The communication system according to any one of claims 1 to claim 3,
The terminal device performs data transmission with the terminal device at a communication speed different from that of other terminal devices . A termination device that is arranged on a network and controls data transmission between a plurality of terminal devices each accommodating a user terminal and the network ,
The storage capacity of the storage unit of the terminal device and the amount of untransmitted data stored in the storage unit among the data received from the user terminal are acquired from the terminal device, and the acquired storage capacity and the untransmitted data are acquired. Based on the estimated time until the storage unit calculated from the difference between the amount of data and the communication speed between the terminal device and the user terminal accommodated with the untransmitted data, the terminal device An allocation process of a band for data transmission to a termination device and a control unit for controlling a time interval of the allocation process are provided.
Termination device comprising a call.

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