JP6553538B2 - Data transmission apparatus, data transmission method and data transmission program - Google Patents

Description

  The present invention relates to a data transmission apparatus, a data transmission method, and a data transmission program.

  FIG. 14 is a diagram showing an example of a configuration of a communication network system in a content distribution service using an IP (Internet Protocol) communication technology. The distribution server transmits data frames in content distribution. In the communication network system, the upstream transfer device regarding the signal flow transmits the data frame of the other service transmission network and the data frame transmitted from the distribution server to the downstream communication network regarding the signal flow.

  In the communication network system, the transmission section of the PON (Passive Optical Network) on the downstream side of the signal flow is an Optical Distribution and Transmission Unit (OLT: Optical Line Terminal), an Optical Distribution and Termination Unit (ONU: Optical Network Unit), and Optical And a splitter.

  The optical distribution / transmission apparatus transmits an optical signal to the optical branching unit via an optical fiber shared by a plurality of optical distribution termination apparatuses. The optical branching unit transmits the same optical signal to all connected optical distribution termination devices regardless of the destination of the optical signal (Non-patent Documents 1 and 2).

  The transfer apparatus transmits the data frame based on the priority assigned to the data frame when the data frame is congested. The optical distribution transmission apparatus transmits an optical signal based on the priority assigned to the data frame when the data frame is congested.

  The priority is a fixed value for each communication service. Data frames with high priority are transmitted prior to data frames with low priority. In communication services such as content distribution using IP communication technology, it may be possible to prevent occurrence of data frame loss and delay by assigning the highest priority to data frames.

“NTT Technical Journal 2005.8 Basic Technology Course [GE-PON Technology] The 1st PON”, [online], [December 25, 2015 search], Internet <URL: http://www.ntt.co .jp / journal / 0508 / files / jn200508071.pdf> IEEE Std 802.3 (TM)-2012 56.1.2 Summary of P2MP sublayer, [online], [Search on December 25, 2015], Internet <URL: http://standards.ieee.org/getieee802/download/802.3 -2012_section5.pdf> RFC2474 Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers, December 1998. ARIB STD-B10 Program information used in digital broadcasting, The Japan Radio Industry Association, [online], [December 25, 2015 search], Internet <URL: http://www.arib.or.jp /english/html/overview/doc/2-STD-B10v5_6.pdf>

  The transfer device discards low priority data frames when the data frames are congested. When the priority of the video / audio data is lower than the priority of the other data frame, the video / audio data frame is lost due to the loss of the IP packet or the transmission delay accompanying the retransmission. When the priority of the video / audio data frame is higher than the priority of other data frames, the quality of communication services other than the content distribution service is deteriorated instead of the loss of the IP video / audio data frame.

  FIG. 15 is a diagram illustrating an example of transmission capacity when a low-priority data frame is discarded. The priority is indicated by, for example, a value based on DSCP (Differentiated Services Code Point) (Non-Patent Document 3). The priority includes, for example, highest priority (EF: Expedited Forwarding), medium priority (AF: Assured Forwarding), and low priority (BE: Best Effort).

  The maximum value (upper limit value) of the transmission capacity (allocated capacity) allocated to the data frame of each priority does not change in principle. For example, when the highest priority data frame increases, the maximum value of the transmission capacity allocated to the medium priority data frame or the low priority data frame may decrease.

  In FIG. 15, the data frame of the video D is newly transmitted. Low priority (BE) is assigned to the data frame of the video D. By newly transmitting the data frame of the image D, the transmission capacity of the low priority data frame exceeds the allocation capacity (maximum value) of the transmission capacity of the low priority data frame. The low priority data frames are lost by an amount exceeding the allocated capacity if the allocated capacity of the low priority data frames does not increase. Which data frame is lost to what extent is determined according to the data frame transmission setting. Multiple data frames with the same priority and handling are probabilistically dropped equally. By pre-assigning the highest priority to the data frame of the highest priority video, loss (loss) of the data frame of the highest priority video can be prevented.

  FIG. 16 is a diagram illustrating a first example of the transmission capacity when the data frame is not discarded. When medium priority is assigned to the data frame of video A and the capacity for sending the data frame of video D remains in the allocated capacity of the data frame of low priority, loss of the data frame of each video can be prevented. it can.

  In content distribution services such as video and audio, it is not always necessary to assign the highest priority to the data frames of the same service stream (CH). For example, since loss of video / audio data frames including emergency broadcast data is not allowed, the highest priority needs to be assigned to video / audio data frames including emergency broadcast data. In FIG. 16, regularly assigning the highest priority to the data frame of video A consumes the assigned capacity of the data frame with the highest priority even when the highest priority need not be assigned.

  In the conventional communication network system, information for the transfer apparatus, the optical distribution transmission apparatus, and the like to determine the priority of the data frame is included in the parameters including the information necessary for transmission. Parameters containing information necessary for transmission are, for example, an IP header and an Ether frame header.

  FIG. 17 is a diagram illustrating a second example of the transmission capacity when the data frame is not discarded. In FIG. 17, the allocated capacity fluctuates. Data frame loss can be prevented by increasing the allocated capacity of low priority data frames and decreasing the allocated capacity of medium priority data frames.

  In FIG. 17, since it is easy to calculate the necessary buffer capacity when the transmission capacity of the data frame is fixed, the method of changing the allocated capacity is effective. When the highest priority or medium priority data frame allocation capacity is available, increase the low priority data frame allocation capacity and receive the highest priority or medium priority data frame. Data frame is lost.

  When the highest priority or medium priority data frame is received by reducing the allocated capacity of the highest priority or medium priority data frame to the same level as the capacity of the data frame being transmitted, the highest priority is received. Data frame is lost.

  In the state shown on the right side of FIG. 17, when the medium priority data frame is received and the allocation capacity of the medium priority data frame is exceeded, the low priority data frame is not discarded, and the medium priority data is not discarded. The frame is discarded. The conventional data transmission apparatus has a problem that it can not prevent the loss of data frames.

  In view of the above circumstances, the present invention has an object to provide a data transmission device, a data transmission method, and a data transmission program that can prevent the loss of data frames.

  One aspect of the present invention is a first communication unit that acquires a data frame to which a priority related to transmission is assigned, and whether or not congestion of the data frame has occurred in the transmission section of the data frame for each priority A congestion detecting unit for detecting the data frame, a change unit for changing the priority assigned to the data frame when the congestion occurs, and transmitting the data frame with the changed priority to the transmission section. And a second communication unit.

  One embodiment of the present invention is the above data transmission apparatus, wherein the frame determination unit determines whether or not the priority of the data frame is a change target based on an identifier included in the data frame. The change unit may change the priority assigned to the data frame when the priority of the data frame is a change target.

  One aspect of the present invention is the above-described data transmission apparatus, further comprising: a prediction unit that predicts, for each priority, the occurrence time of congestion of the data frame in the transmission section, and the change unit includes the data frame The priority assigned to is changed to be earlier than the predicted occurrence time.

  One aspect of the present invention is a data transmission method executed by a data transmission apparatus for transmitting a data frame, which comprises: obtaining a data frame to which a priority related to transmission is assigned; and the data in a transmission section of the data frame Detecting for each priority whether or not congestion of a frame is occurring; changing the priority assigned to the data frame if the congestion is occurring; and And D. transmitting the modified data frame to the transmission section.

  One aspect of the present invention is a procedure for acquiring, in a computer, a data frame to which a priority related to transmission is assigned, and whether or not congestion of the data frame occurs in a transmission section of the data frame. A procedure of detecting the delay, a procedure of changing the priority assigned to the data frame when the congestion occurs, a procedure of transmitting the data frame with the priority changed to the transmission section, and Is a data transmission program for executing.

  The present invention makes it possible to prevent the occurrence of data frame loss.

FIG. 1 is a diagram illustrating an example of a configuration of a communication network system in an embodiment. It is a figure which shows the 1st example of a structure of an optical distribution transmission apparatus in embodiment. It is a figure which shows the example of flame | frame information in embodiment. It is a figure which shows the example of connection area information in embodiment. It is a figure which shows the example of the process which determines a data frame in embodiment. It is a figure which shows the example of congestion notification and cancellation | release notification in embodiment. It is a figure which shows the example of the change rule of a priority in embodiment. It is a figure which shows the example of the change process of a priority in embodiment. It is a figure which shows the 2nd example of a structure of an optical distribution transmission apparatus in embodiment. It is a figure which shows the example of the process in which a priority determination process part determines whether the priority of a data frame is a priority of a change object in embodiment. It is a figure which shows the 3rd example of a structure of an optical distribution transmission apparatus in embodiment. It is a figure which shows the example of generation | occurrence | production prediction of congestion in embodiment. It is a figure which shows the example of the transmission capacity before changing a priority in embodiment, and the transmission capacity after changing a priority. It is a figure which shows the example of a structure of a communication network system in the content delivery using IP communication technology. It is a figure which shows the example of transmission capacity in, when discard of the data frame of low priority generate | occur | produces. It is a figure which shows the 1st example of transmission capacity in, when discard of a data frame does not generate | occur | produce. It is a figure which shows the 2nd example of transmission capacity in, when discard of a data frame does not generate | occur | produce.

Embodiments of the present invention will be described in detail with reference to the drawings.
First Embodiment
FIG. 1 is a diagram showing an example of the configuration of the communication network system 1. The communication network system 1 is a system that provides a communication service using IP communication technology. The communication service is, for example, a content distribution service. The communication network system 1 includes a multicast transmission section such as PON. In FIG. 1, a communication network system 1 includes a distribution server 2, a transfer device 3 on the upstream side with respect to the flow of data frames, a transfer device 4 on the downstream side with respect to the flow of data frames, an optical distribution transmission device 5, and an optical branch. And a distribution device 8, a distribution device 8, and a reception terminal 9. Each of the transfer device 4, the optical distribution and transmission device 5, the optical branching device 6, the optical distribution and termination device 7, the distribution device 8 and the reception terminal 9 may be plural.

  The distribution server 2 transmits the data frame to which the priority is assigned to the transfer device 3. The transfer device 3 transmits the data frame acquired from the distribution server 2 to the transfer device 4. The transfer device 3 may transmit the data frame acquired from the other service transmission network (NW) to the transfer device 4. The transfer device 4 transmits the data frame acquired from the transfer device 3 to the optical distribution and transmission device 5. The transfer device 4 may transmit the data frame acquired from the other service transmission network (NW) to the optical distribution transmission device 5.

  The optical distribution and transmission apparatus 5 (OLT) acquires a data frame from the transfer apparatus 4. The optical distribution and transmission apparatus 5 transmits an optical signal based on a data frame to the optical splitter 6 via a common optical fiber. The optical splitter 6 transmits an optical signal to the optical distribution and termination device 7 via an optical fiber. The optical splitter 6 may transmit optical signals to the plurality of optical distribution and termination devices 7 via an optical fiber.

  The optical distribution termination device 7 (ONU) transmits a data frame based on the optical signal to the distribution device 8. The distribution device 8 transmits the data frame to the receiving terminal 9 based on the destination assigned to the data frame. The receiving terminal 9 acquires a data frame from the distribution device 8.

The configuration of the optical distribution transmission apparatus 5 will be described.
FIG. 2 is a diagram illustrating a first example of the configuration of the optical distribution / transmission apparatus 5. In the following, the flow of the video / audio data frame is represented by a solid line arrow. The flows of data frames other than video and audio (other data frames) are represented by dashed arrows.

  The optical distribution transmission device 5 (data transmission device) includes a frame information registration processing unit 501, a frame information storage unit 502, an upstream transmission / reception processing unit 503, a connection area information storage unit 504, and a data frame determination processing unit 505. And a congestion determination processing unit 506, a priority setting change processing unit 507, and a downstream transmission / reception processing unit 508.

  For example, part or all of the frame information registration processing unit 501, the upstream transmission / reception processing unit 503, the data frame determination processing unit 505, the congestion determination processing unit 506, the priority setting change processing unit 507, and the downstream transmission / reception processing unit 508 A processor such as a CPU (Central Processing Unit) is a software function unit that functions by executing a program stored in a storage unit. Further, some or all of these functional units may be hardware functional units such as LSI (Large Scale Integration) and ASIC (Application Specific Integrated Circuit).

  A part or all of the data frame determination processing unit 505, the congestion determination processing unit 506, and the priority setting change processing unit 507 may be included in another device in the communication network system 1. For example, part or all of the data frame determination processing unit 505, the congestion determination processing unit 506, and the priority setting change processing unit 507 are relays used in an IP network system such as a router, L3SW, L2SW, or optical distribution transmission apparatus. The transmission device may be provided. Some or all of the data frame determination processing unit 505, the congestion determination processing unit 506, and the priority setting change processing unit 507 may be provided in a plurality of devices in the communication network system 1.

  The frame information registration processing unit 501 acquires frame information. The frame information is information for determining whether the data frame is a target whose priority is to be changed. The frame information registration processing unit 501 causes the frame information storage unit 502 to store frame information.

  FIG. 3 is a diagram showing an example of frame information. In the frame information, parameters included in the video / audio data frame are associated with each other. In FIG. 3, the data frame number, the source IP address (IP src), the destination IP address (IP dst), the normal priority, and the distributable area information are associated with each other. Frame information may include many more items.

  In FIG. 3, the format of the source IP address is the IPv6 format. The format of the destination IP address is a multicast format in the IPv6 format. The format of the source IP address and the destination IP address may be, for example, an IPv4 format or a MAC address (Media Access Control address) format used in Ethernet (registered trademark).

  The format of the transmission source IP address and the transmission destination IP address may be a format in which a plurality of addresses are expressed together. For example, the transmission source IP address may be written as “2015: 1032: 1001: 8001 :: / 64”. The destination IP address may be expressed as “ff33: 1000 :: 110F :: / 120”.

  The priority in the case where congestion does not occur (normal time) is represented by the value (identifier) included in the data frame. The value (identifier) included in the data frame is, for example, a DSCP value. The values included in the data frame are, for example, values included in the IP header of the data frame. For example, when the DSCP value included in the IP header of the data frame is “34”, “36” or “38”, the value representing the priority is defined as “AF 4”. For example, when the DSCP value included in the IP header of the data frame is “0”, the value indicating the priority is defined as “BE”.

  The distributable area information is information representing an area where it is possible to distribute the data frame of the associated number. In FIG. 3, it is acceptable to deliver a data frame whose source IP address is “2015: 1031 :: 1001” and whose destination IP address is “ff 33: 1000 :: 1001” to the Kanto wide area (010110100101). It is done. The distributable area information may be a value based on the area code defined in Article 9-3, No. 5 of the Radio Equipment Rules, Article 138 of the Radio Station Operation Rules, and the Ministry of Posts and Telecommunications Notification No. 405 of 1985. In FIG. 3, a plurality of distributable area information may be determined for each data frame number.

  The frame information storage unit 502 shown in FIG. 2 is configured using a storage device having a nonvolatile storage medium (non-temporary recording medium) such as a magnetic hard disk device or a semiconductor storage device. The frame information storage unit 502 may include, for example, a volatile storage medium such as a RAM (Random Access Memory) or a register. The frame information storage unit 502 stores frame information.

  The upstream side transmission / reception processing unit 503 (first communication unit) acquires, from the transfer device 4, a data frame to which a priority related to transmission is assigned. The upstream side transmission / reception processing unit 503 transmits, to the data frame determination processing unit 505, the data frame to which the priority regarding transmission is assigned.

  The connection area information storage unit 504 is configured using a storage device having a nonvolatile storage medium (non-temporary recording medium) such as a magnetic hard disk device or a semiconductor storage device. The connection area information storage unit 504 may include, for example, a volatile storage medium such as a RAM or a register. The connection area information storage unit 504 stores connection area information. The connection area information is information representing an area where the optical distribution termination device 7 connected downstream from the optical distribution transmission device 5 is installed. The connection area information may be determined based on the area code defined in Article 9-3 of the Radio Equipment Rules, Article 138 of the Radio Station Operation Rules and Article 138 of the Ministry of Posts and Telecommunications Notification No. 405 of 1985. .

  FIG. 4 is a diagram showing an example of connection area information. In FIG. 4, the connection area information is defined for each transmission port number of the downstream transmission / reception processing unit 508. A plurality of connection area information may be determined for each transmission port number of the downstream transmission / reception processing unit 508. In FIG. 4, connection area information “Tokyo (101010101100)” is defined for the transmission port “P1”.

  The data frame determination processing unit 505 (frame determination unit) acquires the data frame from the upstream transmission / reception processing unit 503. The data frame determination processing unit 505 determines whether or not the acquired data frame is a data frame whose priority is to be changed based on at least one of the frame information and the connection area information.

  When the acquired data frame is a data frame whose priority is to be changed, the data frame determination processing unit 505 transmits the data frame to the priority setting change processing unit 507. When the acquired data frame is not a data frame whose priority is to be changed, the data frame determination processing unit 505 transmits the data frame to the downstream transmission / reception processing unit 508.

  FIG. 5 is a diagram illustrating an example of processing of determining a data frame. The data frame determination processing unit 505 acquires a data frame (step S101). The data frame determination processing unit 505 determines whether the data frame is video / audio data to be managed by the optical distribution transmission apparatus 5. That is, the data frame determination processing unit 505 determines whether or not the transmission source IP address, the transmission destination IP address, and the distributable area information are included in the frame information (step S102).

  The data frame determination processing unit 505 may determine whether the data frame is a video / audio data frame to be managed by the optical distribution transmission apparatus 5 based on the value of the VLAN-ID.

  When the frame information includes the transmission source IP address, the transmission destination IP address, and the distributable area information (step S102: YES), the data frame determination processing unit 505 refers to the distribution area information of the acquired data frame. . The delivery area information is, for example, “area_code” (see Non-Patent Document 4) included in the emergency information descriptor of the SI information of the video signal of the data frame. The system of the value of "area_code" is the same as the distributable area information in the frame information.

  The data frame determination processing unit 505 determines whether “area_code” is an area common code. The regional common code is a code indicating that the entire region is to be distributed. If the “area_code” is not an area common code (step S103: NO), the data frame determination processing unit 505 determines whether the “area_code” is a code (wide area code) representing a wide area including a distributable area. If "area_code" is not a code representing a wide area including a distributable area (is a prefectural area code) (step S104: NO), the data frame determination processing unit 505 determines whether "area_code" matches distributable area information It is determined (step S105).

  When the result of step S103, step S104, or step S105 is “YES”, the data frame determination processing unit 505 determines whether the priority of the data frame is a change target for the acquired data frame. That is, when the result of step S103, step S104 or step S105 is "YES", the data frame determination processing unit 505 determines, for the acquired data frame, whether or not the priority of the data frame needs to be changed. Do.

  For example, when the data frame includes information (urgent broadcast data) indicating urgency, the data frame determination processing unit 505 determines that the priority of the data frame is to be changed. For example, when the value of “start_end_flag” (see Non-Patent Document 4) in the emergency information descriptor (identifier) of the SI information of the video signal included in the data frame is data It is determined that the priority of the frame is to be changed (step S106).

  The data frame determination processing unit 505 transmits the data frame to the priority setting change processing unit 507 (step S107) when the priority of the data frame is to be changed (step S106: YES).

  When the result of step S102, step S105, or step S106 is “NO”, the data frame determination processing unit 505 transmits the data frame to the downstream transmission / reception processing unit 508 (step S108).

  The congestion determination processing unit 506 shown in FIG. 2 has information (hereinafter “transmission capacity information”) indicating the capacity of the data frame (hereinafter referred to as “transmission capacity”) transmitted by the downstream transmission / reception processing unit 508 to the optical splitter 6. Is acquired from the downstream transmission / reception processing unit 508 for each data frame priority. The congestion determination processing unit 506 determines, for each priority, whether or not the downstream side of the downstream transmission / reception processing unit 508 is in a congestion state with respect to the data frame flow based on the transmission capacity information. That is, the congestion determination processing unit 506 (congestion detection unit) determines, on the basis of the transmission capacity information, whether or not congestion of data frames occurs in the downstream transmission section of the downstream transmission / reception processing unit 508. To detect.

  The congestion determination processing unit 506 compares the transmission capacity with the upper limit (hereinafter referred to as “transmission capacity upper limit”) of the transmission capacity allocated on the downstream side of the downstream transmission / reception processing unit 508. When the transmission capacity is equal to or more than the transmission capacity upper limit value, the congestion determination processing unit 506 determines that the downstream side of the downstream transmission / reception processing unit 508 is in a congested state regarding the flow of the data frame. When the congestion determination processing unit 506 determines that the downstream side of the downstream side transmission / reception processing unit 508 is in a congested state, the congestion determination processing unit 506 transmits a congestion notification to the priority setting change processing unit 507.

  When the transmission capacity is less than the transmission capacity upper limit value, the congestion determination processing unit 506 determines that the congestion state has been eliminated on the downstream side of the downstream transmission / reception processing unit 508 regarding the flow of the data frame. If the congestion determination processing unit 506 determines that the congestion state has been eliminated on the downstream side of the downstream transmission / reception processing unit 508, the congestion determination processing unit 506 transmits a cancellation notification to the priority setting change processing unit 507.

  FIG. 6 is a diagram showing an example of congestion notification and cancellation notification. In the congestion notification, the priority and the congestion state are associated. In the congestion notification, when the congestion state is “congested”, the congestion state is associated with the data loss capacity. Data loss capacity is the capacity of a missing data frame. In the congestion notification, when the congestion state is “no congestion”, the congestion state is associated with the free capacity. In the cancellation notification, the priority, the congestion state, and the free space are associated with each other. In the cancellation notification, the congestion state is "no congestion".

  When the priority setting change processing unit 507 (change unit) illustrated in FIG. 2 obtains the congestion notification from the congestion determination processing unit 506, the downstream side transmission / reception processing unit for the data frame having the priority “congested”. It is determined that the downstream side of 508 is in a congested state. When the priority setting change processing unit 507 acquires the cancellation notification from the congestion determination processing unit 506, the congestion state on the downstream side of the downstream transmission / reception processing unit 508 is obtained for the data frame of the priority of "no congestion". It is determined that it has been resolved.

  FIG. 7 is a diagram showing an example of a setting rule of priority setting. The priority setting change processing unit 507 acquires the data frame of the priority determined to be “congested”, and changes the priority of the acquired data frame when there is free space that can transmit the data frame. Data frames that need to be changed in priority are highly important data frames.

  The priority setting change processing unit 507 acquires a priority one level higher than the priority of the acquired data frame when the data frame with a priority higher by one level than the priority of the acquired data frame is not congested. Change the priority of data frame. When the priority setting change processing unit 507 is in a congestion state where the priority is one step higher than the priority of the acquired data frame, the priority setting change processing unit 507 is a data frame having a priority two steps higher than the priority of the acquired data frame Is determined whether or not it is in a congested state. The priority setting change processing unit 507 acquires a priority that is two levels higher than the priority of the acquired data frame when the data frame having a priority that is two levels higher than the priority of the acquired data frame is not congested. Change the priority of data frame.

  The priority setting change processing unit 507 may not change the priority when data frames having all the priority levels including the highest priority level are in a congestion state. The priority setting change processing unit 507 may change the priority of the data frame to a relatively low priority according to the content of the communication service.

  FIG. 8 is a diagram showing an example of priority change processing. The priority setting change processing unit 507 acquires a data frame whose priority is to be changed (step S201). The priority setting change processing unit 507 determines whether or not a data frame having the same priority as that of the acquired data frame is not congested (step S202).

  The priority setting change processing unit 507 determines not to change the priority of the acquired data frame when the data frame having the same priority as the acquired data frame is not congested (step S202: YES) (step S202: YES). Step S203). The priority setting change processing unit 507 transmits the data frame to the downstream transmission / reception processing unit 508 (step S204).

  If the data frame having the same priority as the priority of the acquired data frame is in a congested state (step S202: NO), the priority setting change processing unit 507 has a priority one step higher than the priority of the acquired data frame. It is determined whether or not there is free space which can transmit the acquired data frame in the transmission capacity of the data frame (step S205).

  The priority setting change processing unit 507 increases the priority of the acquired data frame by one level (step S206) when there is a free capacity capable of transmitting the acquired data frame (step S205: YES). The priority setting change processing unit 507 advances the process to step S204.

  If there is no free space available to transmit the acquired data frame (step S205: NO), the priority setting change processing unit 507 sets the transmission capacity of the data frame having a priority one step higher than the priority of the acquired data frame. It is determined whether there is free space available to transmit the acquired data frame (step S207). The priority setting change processing unit 507 may repeat step S207 n times (n is the number of divisions of priority).

  The priority setting change processing unit 507 sets the priority of the acquired data frame to the highest priority when there is a free space to which the acquired data frame can be transmitted at the highest priority which is n steps higher priority (step S207: YES). (Step S208). The priority setting change processing unit 507 advances the process to step S204.

  If there is no free space available to transmit the acquired data frame in the highest priority which is n levels higher than the priority setting change processing unit 507 (step S207: NO), the priority setting change processing unit 507 has one more priority than the acquired data frame priority. It is determined whether the transmission capacity of the low-priority data frame has a vacant capacity capable of transmitting the acquired data frame (step S209).

  When the transmission capacity of the data frame having a priority level one step lower than the acquired data frame priority has a free space to which the acquired data frame can be transmitted (step S209: YES), the priority setting change processing unit 507 The priority of the acquired data frame is set to one step lower priority (step S210). The priority setting change processing unit 507 advances the process to step S204.

  If there is no free space to which the acquired data frame can be transmitted, the priority setting change processing unit 507 does not have the transmission capacity of the data frame having a priority level one step lower than the acquired data frame priority (step S209: NO) It is determined whether or not there is free space that can transmit the acquired data frame in the transmission capacity of the data frame having a priority n steps lower than the acquired data frame priority (step S211).

  If the priority setting change processing unit 507 determines that the transmission capacity of the data frame having a priority n steps lower than the priority of the acquired data frame has free space to transmit the acquired data frame (YES in step S211), The priority of the acquired data frame is set to n steps lower than the priority (step S212). The priority setting change processing unit 507 advances the process to step S204.

  When there is no free space to transmit the acquired data frame in the transmission capacity of the data frame having a priority n steps lower than the acquired data frame priority (step S211: NO), the priority setting change processing unit 507 It is decided not to change the priority of the acquired data frame (step S213). The priority setting change processing unit 507 advances the process to step S204.

  The downstream side transmission / reception processing unit 508 (second communication unit) acquires a data frame from the data frame determination processing unit 505 or the priority setting change processing unit 507. The downstream transmission / reception processing unit 508 transmits the acquired data frame to the optical distribution and termination device 7 via the optical splitter 6. The downstream transmission / reception processing unit 508 transmits transmission capacity information to the congestion determination processing unit 506 for each priority of the transmitted data frame.

  As described above, the optical distribution transmission apparatus 5 according to the first embodiment includes the upstream transmission / reception processing unit 503, the congestion determination processing unit 506, the priority setting change processing unit 507, and the downstream transmission / reception processing unit 508. . The upstream transmission / reception processing unit 503 acquires a data frame to which a priority related to transmission is assigned. The congestion determination processing unit 506 detects, for each priority level, whether or not data frame congestion occurs in the data frame transmission section. The priority setting change processing unit 507 changes the priority assigned to the data frame when congestion occurs. The downstream transmission / reception processing unit 508 transmits the data frame whose priority has been changed to the transmission section.

  As a result, the optical distribution / transmission apparatus 5 of the first embodiment can prevent data frame loss.

  The optical distribution / transmission apparatus 5 of the first embodiment further includes a data frame determination processing unit 505. The data frame determination processing unit 505 determines whether or not the priority of the data frame is a change target based on the identifier included in the data frame. The priority setting change processing unit 507 changes the priority assigned to the data frame when the priority of the data frame is a change target.

  Thereby, the optical distribution / transmission apparatus 5 of the first embodiment can determine the priority of the data frame based on the characteristics of the video / audio content. The characteristics of the contents of video and audio are, for example, whether or not emergency broadcast data (emergency alert signal) is included in a data frame. The optical distribution transmission apparatus 5 of the first embodiment can dynamically change the value of the priority included in the header or the like of the data frame based on the content of the data frame.

Second Embodiment
The second embodiment is different from the first embodiment in that the optical distribution transmission apparatus includes a priority determination processing unit. In the second embodiment, only differences from the first embodiment will be described.

  FIG. 9 is a diagram showing a second example of the configuration of the optical distribution transmission apparatus 5. As shown in FIG. The optical distribution transmission apparatus 5 includes a frame information registration processing unit 501, a frame information storage unit 502, an upstream transmission / reception processing unit 503, a connection area information storage unit 504, a data frame determination processing unit 505, and a congestion determination processing unit. 506, a priority setting change processing unit 507, and a downstream transmission / reception processing unit 508. The optical distribution and transmission apparatus 5 further includes a priority determination processing unit 509 between the data frame determination processing unit 505 and the downstream transmission / reception processing unit 508.

  The data frame determination processing unit 505 determines whether or not the data frame is video / audio data to be managed by the optical distribution transmission apparatus 5 based on the value representing the priority included in the header of the data frame. . The priority setting change processing unit 507 may not have to change the priority of the data frame.

  The priority determination processing unit 509 (priority determination unit) acquires, from the data frame determination processing unit 505, a value representing the priority included in the header of the data frame. The priority determination processing unit 509 determines whether the priority of the acquired data frame is to be changed or not based on a value representing the priority included in the header of the data frame. That is, the priority determination processing unit 509 determines whether to change the priority of the acquired data frame based on the value indicating the priority included in the header of the data frame. For example, the priority determination processing unit 509 determines whether the priority of the acquired data frame is to be changed or not when congestion occurs in the transmission section.

  FIG. 10 is a diagram illustrating an example of processing in which the priority determination processing unit 509 determines whether or not the priority of the data frame is a change target. The priority determination processing unit 509 acquires a candidate data frame whose priority is to be changed from the data frame determination processing unit 505 (step S301). The priority determination processing unit 509 determines whether or not the priority of the acquired data frame is a change target (step S302).

  In FIG. 10, the priority to be changed is, for example, the highest priority. When the priority of the acquired data frame is the highest priority (step S302: YES), the priority determination processing unit 509 transmits the acquired data frame to the priority setting change processing unit 507 (step S303). When the priority of the acquired data frame is not the highest priority (step S302: NO), the priority determination processing unit 509 transmits the acquired data frame to the downstream transmission / reception processing unit 508 (step S304).

  The data frame determination processing unit 505 may determine whether the priority of the acquired data frame is to be changed, instead of the priority determination processing unit 509.

  The downstream transmission / reception processing unit 508 illustrated in FIG. 9 acquires a data frame from the data frame determination processing unit 505, the priority setting change processing unit 507, or the priority determination processing unit 509. The downstream transmission / reception processing unit 508 transmits the acquired data frame to the optical distribution and termination device 7 via the optical splitter 6. The downstream transmission / reception processing unit 508 transmits transmission capacity information to the congestion determination processing unit 506 for each priority of the transmitted data frame.

  As described above, the priority determination processing unit 509 according to the second embodiment determines whether the priority of the acquired data frame is the change target, as a value representing the priority included in the header of the data frame. Determine based on.

  As a result, the optical distribution transmission apparatus 5 of the second embodiment can prevent the loss of data frames even when the priority of data frames is not changed with respect to the predetermined priority.

Third Embodiment
The third embodiment is different from the second embodiment in that the light distribution transmission apparatus includes a congestion prediction determination processing unit. In the third embodiment, only differences from the second embodiment will be described.

  FIG. 11 is a diagram illustrating a third example of the configuration of the optical distribution transmission apparatus 5. The optical distribution transmission apparatus 5 includes a frame information registration processing unit 501, a frame information storage unit 502, an upstream transmission / reception processing unit 503, a connection area information storage unit 504, a data frame determination processing unit 505, and a congestion determination processing unit. 506, a priority setting change processing unit 507, a downstream transmission / reception processing unit 508, and a priority determination processing unit 509. The optical distribution and transmission apparatus 5 further includes a transmission capacity information storage unit 510 and a congestion prediction determination processing unit 511.

  The downstream side transmission / reception processing unit 508 acquires a data frame from the data frame determination processing unit 505, the priority setting change processing unit 507, or the priority determination processing unit 509. The downstream transmission / reception processing unit 508 transmits the acquired data frame to the optical distribution and termination device 7 via the optical splitter 6. The downstream transmission / reception processing unit 508 transmits transmission capacity information to the congestion prediction determination processing unit 511 for each priority of the transmitted data frame.

  The transmission capacity information storage unit 510 is configured using a storage device having a non-volatile storage medium (non-temporary storage medium) such as a magnetic hard disk drive or a semiconductor storage device. The transmission capacity information storage unit 510 may include, for example, a volatile storage medium such as a RAM or a register. The transmission capacity information storage unit 510 stores transmission capacity information accumulated as a history of transmission capacity.

  The congestion prediction determination processing unit 511 stores the transmission capacity information in the transmission capacity information storage unit 510. The congestion prediction determination processing unit 511 executes a congestion determination process in the same manner as the congestion determination processing unit 506.

  The congestion prediction determination processing unit 511 (prediction unit) predicts the occurrence time of congestion of the data frame on the downstream side of the downstream transmission / reception processing unit 508 with respect to the flow of the data frame based on the transmission capacity information for each priority. The congestion prediction determination processing unit 511 predicts the congestion occurrence time of the data frame by analyzing the congestion occurrence period based on the transmission capacity information.

  The congestion prediction determination processing unit 511 may periodically predict the timing of occurrence of data frame congestion. For example, the congestion prediction determination processing unit 511 may predict the occurrence timing of data frame congestion every week by executing an analysis process every week.

  FIG. 12 is a diagram showing an example of congestion occurrence prediction. The horizontal axis shows time (one week). The vertical axis indicates the transmission capacity of the low priority data frame. In FIG. 12, “BE allocated capacity” indicates the allocated capacity of the low priority data frame. The time when the transmission capacity of the low priority data frame exceeds the allocated capacity of the low priority data frame is the time when congestion occurs.

In Figure 12, T ₁ indicates the predicted time which congestion occurs (predicted occurrence time). The congestion prediction determination processing unit 511 sends a congestion occurrence prediction notification to the priority setting change processing unit 507 at the time T ′ (= T ₁ −T _M ) before the prediction time T ₁ by the prediction margin time T _M. Send every. When the congestion state is resolved, the congestion prediction determination processing unit 511 transmits a cancellation notification to the priority setting change processing unit 507 for each priority. The prediction margin time _TM is determined in advance. For example, when the prediction margin time T _M is 5 seconds and the prediction time T ₁ is 10:00, the congestion prediction determination processing unit 511 sends a congestion occurrence prediction notification at time T ′ (9:59:55). It transmits to the priority setting change processing unit 507 for each priority.

Congestion prediction determination processing unit 511, if the congestion has not occurred between the predicted time T ₁ until the congestion determination completion time T '', and transmits the cancellation notification for each priority in the priority setting change processing unit. Therefore, when congestion has not occurred between the predicted time T ₁ until the congestion determination completion time T '', waiting time until the congestion prediction determination processing unit 511 transmits the cancellation notification (congestion prediction determination time) I Is the difference between the time T ″ and the predicted time T ₁ . The congestion prediction judgment processing unit 511 transmits the cancellation notification at the time when the waiting time has elapsed, so that the congestion prediction judgment processing unit 511 changes the priority even though no congestion has actually occurred. This situation can be avoided early.

  FIG. 13 is a diagram illustrating an example of the transmission capacity before the priority is changed and the transmission capacity after the priority is changed. In FIG. 13, a low priority (BE) is assigned to the data frame of the video D.

  When the emergency broadcast data is not attached to the data frame of the video A, a low priority (BE) is assigned to the data frame of the video A. When the emergency broadcast data is added to the data frame of video A, the data frame of video A is assigned the highest priority (EF). Since the highest priority is assigned to the data frame of video A, there is a margin in the transmission capacity of the low priority data frame.

  By this, even when the data frame of the video D is newly transmitted, the transmission capacity of the low priority data frame does not exceed the allocation capacity (maximum value) of the transmission capacity of the low priority data frame. .

  As described above, the optical distribution / transmission apparatus 5 according to the third embodiment further includes the congestion prediction determination processing unit 511. The congestion prediction determination processing unit 511 predicts the occurrence time of data frame congestion in the transmission section for each priority. The priority setting change processing unit 507 changes the priority assigned to the data frame before the predicted occurrence time.

  As a result, the optical distribution / transmission apparatus 5 of the third embodiment can prevent data frame loss.

  You may make it implement | achieve at least one part of data transmission apparatuses, such as the optical distribution transmission apparatus in embodiment mentioned above, with a computer. In that case, a program for realizing this function may be recorded in a computer readable recording medium, and the program recorded in the recording medium may be read and executed by a computer system. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be for realizing a part of the functions described above, or may be realized in combination with the program already recorded in the computer system. You may implement | achieve using programmable logic devices, such as FPGA (Field Programmable Gate Array).

  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 design and the like within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Communication network system, 2 ... Distribution server, 3 ... Transfer apparatus, 4 ... Transfer apparatus, 5 ... Optical distribution transmission apparatus, 6 ... Optical branching device, 7 ... Optical distribution termination apparatus, 8 ... Distribution apparatus, 9 ... Reception terminal 501: frame information registration processing unit 502: frame information storage unit 503: upstream transmission / reception processing unit 504: connection area information storage unit 505: data frame determination processing unit 506: congestion determination processing unit 507: priority Degree setting change processing unit 508: Downstream transmission / reception processing unit 509: priority determination processing unit 510: transmission capacity information storage unit 511: congestion prediction determination processing unit

Claims (4)

A first communication unit that acquires a data frame to which a priority related to transmission is assigned;
A congestion prediction unit that predicts, for each priority , occurrence time of congestion of the data frame in the transmission section of the data frame;
If congestion of said data frame Ru is predicted, and a changing unit for changing the priority assigned to the data frame, prior to the predicted the occurrence time,
A second communication unit configured to transmit the data frame whose priority has been changed to the transmission section ;
The data transmission device , wherein the change unit stops changing the priority when congestion does not occur between the predicted occurrence time and a time when a predetermined waiting time elapses . A frame determination unit for determining whether the priority of the data frame is a change target based on an identifier included in the data frame;
The data transmission apparatus according to claim 1, wherein the changing unit changes the priority assigned to the data frame when the priority of the data frame is a change target. A data transmission method executed by a data transmission apparatus for transmitting a data frame,
An acquisition step for acquiring a data frame assigned a priority for transmission;
A prediction step of predicting the time of occurrence of congestion of the data frame for each of the priority in the transmission section of the data frame,
If congestion of said data frame Ru is predicted, a changing step of changing the priority assigned to the data frame, prior to the predicted the occurrence time,
Look including a transmission step of transmitting the data frame to the priority is changed to the transmission section,
The data transmission method , wherein, in the changing step, the priority change is stopped when congestion does not occur between the predicted occurrence time and a time when a predetermined waiting time elapses . On the computer
An acquisition procedure for acquiring a data frame assigned a priority for transmission;
A prediction procedure for predicting, for each priority , occurrence time of congestion of the data frame in a transmission section of the data frame;
If congestion of said data frame Ru is predicted, the priority assigned to the data frame, a change procedure for changing before the predicted the occurrence time,
A data transmission program for executing a transmission procedure for transmitting the data frame with the changed priority to the transmission section ,
In the change procedure, the priority change is stopped when congestion does not occur between the predicted occurrence time and a time when a predetermined waiting time has elapsed .

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