JP2013123111A - Packet multiplex transmission device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a packet multiplex transmission device and method which, while preventing packets from being discarded, can reduce a delay in signal transmission.SOLUTION: In a packet multiplex transmission device and method, determination is made to see if congestion has occurred, and when congestion is determined to have not occurred, the oldest of first packets stored in buffer memory which temporarily retains first packets before multiplexing is capsulated before being output. On the other hand, when congestion is determined to have occurred, a number of the first packets to be combined is calculated, and a number of the first packets equal to the calculated packet count are combined and capsulated in order from the oldest of the first packets stored in the buffer memory before being output.

Description

  The present invention relates to a packet multiplex transmission apparatus and method, for example, a packet multiplex transmission apparatus that encapsulates a packet communication signal represented by Ethernet (registered trademark) defined in IEEE (Institute of Electrical and Electronic Engineers) 802.3. It is suitable for application to.

  In recent years, broadband lines such as the Internet have become widespread. Along with this, the demand for circuits is increasing mainly for IP (Internet Protocol) traffic, and so far, SDH / SONET (Synchronous Digital Hierarchy / Synchronous Optical NETwork) and ATM (Asynchronous Optical NETwork), which have been the mainstream of WAN (World Wide Name). Instead of Transfer Mode, etc., Ethernet (registered trademark) with large capacity and low cost is rapidly spreading in the market.

  The Ethernet signal is composed of a MAC (Media Access Control) frame defined by IEEE 802.3 and data of 12 bytes or more representing a no-signal state called IFG (Inter Frame Gap) between the MAC frames. The MAC is a protocol belonging to the second layer (layer 2) of the OSI (Open Systems Interconnection) reference model, and its role is to transfer the protocol and data of the third layer (layer 3) and higher of the OSI reference model to the MAC packet. By storing them in the data area, it is possible to reliably transmit these protocols and data to the target terminal.

  Furthermore, in recent years, based on the backbone network based on the SDH / SONET technology using the time-division multiplexing technology that has existed for a long time, and the IP / Ethernet (registered trademark) technology that transmits information in the form of a packet packet that has started to appear. It is in a situation where the backbone network to coexist.

  Under these circumstances, the communication carrier is required for SDH / SONET signals and IP / Ethernet (registered trademark) frames to eliminate the inefficiency of maintenance because of the installation of these backbone networks. We are investigating aggregating the packet communication based backbone network by adding the same standard header and footer to encapsulate. As a result of this study, for example, ITU-T Y.1370.1 and Y.1371 define the T-MPLS (Transport-MPLS) technology. Such a packet multiplex transmission apparatus to which T-MPLS is applied has a feature that it can accommodate signals of various communication standards and can have a flexible network configuration.

  As a technique related to a packet combination transmission method applicable to such a packet multiplex transmission apparatus, for example, in Patent Document 1, a packet combination process is executed even at a predetermined packet transmission timing even when the packet combination number is less than a specified number. Thus, a method for reducing the packet combining processing delay is disclosed. Patent Document 2 discloses a method for reducing delay time by constantly measuring the traffic volume per unit time of traffic, predicting a waiting time in packet combination, and changing the number of packet combinations based on the prediction result. Is disclosed.

JP 2008-66817 A JP-A-2-295256

IEEE802.3 ITU-T Y.1370.1 ITU-T Y.1371

  However, according to the packet combination transmission methods disclosed in Patent Document 1 and Patent Document 2, there is a problem in that a waiting time is generated during packet combination processing and a signal transmission is delayed as described later.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose a packet multiplex transmission apparatus and method capable of reducing signal transmission delay while preventing packet discarding.

  In order to solve this problem, in the present invention, a plurality of types of transmission signals are accommodated, non-packet signals are packetized, packet signals are accommodated as packet signals, and each packet signal is multiplexed and output. In the packet multiplex transmission apparatus, the transmission signals are sequentially packetized or accommodated as packet signals and the first packets are sequentially generated, and the first packets are encapsulated to generate second packets of the same standard. A multiplexing pre-processing unit that sequentially generates, and a multiplexing unit that multiplexes the second packet generated by each of the multiplexing pre-processing units, wherein the multiplexing pre-processing unit outputs each of the transmission signals A signal processing unit that sequentially generates packets and sequentially generates the first packet; and temporarily stores the first packet and stores the first packet A standby buffer unit that encapsulates packets and sequentially generates the second packet, the standby buffer unit temporarily storing the first packet, and the first buffer in the buffer memory A buffer monitoring unit that monitors the staying amount of the packet, and a packet combination processing unit that encapsulates the first packet into the second packet based on a monitoring result of the buffer monitoring unit, wherein the buffer monitoring unit includes: And determining whether or not congestion has occurred based on the amount of staying of the first packet in the buffer memory. If it is determined that congestion has occurred, the number of packets of the first packet to be combined And the packet combination processing unit stores the buffer memory when the buffer monitoring unit determines that congestion has not occurred. If the buffer monitoring unit determines that congestion has occurred while encapsulating and outputting the oldest first packet among the first packets being stored, the buffer memory stores The first packets corresponding to the number of packets calculated by the buffer monitoring unit in order from the oldest packet among the first packets are combined, encapsulated, and output.

  Further, in the present invention, a packet multiplex transmission method for accommodating a plurality of types of transmission signals, packetizing non-packet signals, accommodating packet signals as packet signals, and multiplexing and outputting each packet signal In the above, each of the transmission signals is sequentially packetized or accommodated as it is to generate a first packet sequentially, and the first packet is encapsulated to sequentially generate second packets of the same standard A preprocessing unit, and a multiplexing unit that multiplexes the second packet generated by each of the multiplexing preprocessing units, wherein the multiplexing preprocessing unit sequentially packetizes or transmits each transmission signal A signal processing unit that accommodates the signal as it is and sequentially generates the first packet, and temporarily stores the first packet A standby buffer unit that encapsulates a first packet and sequentially generates the second packet, the standby buffer unit temporarily storing the first packet; and a buffer memory in the buffer memory A buffer monitoring unit that monitors the first retention amount; and a packet combination processing unit that encapsulates the first packet into the second packet based on a monitoring result of the buffer monitoring unit, The buffer monitoring unit determines whether congestion has occurred based on the retention amount of the first packet in the buffer memory, and when determining that congestion has occurred, the first buffer to be combined When the buffer monitoring unit determines that the first step of calculating the number of packets of the packet and the packet combination processing unit is not congested, When the buffer monitoring unit determines that congestion has occurred while encapsulating and outputting the oldest first packet among the first packets stored in the buffer memory, A second packet that is combined with the first packets for the number of packets calculated by the buffer monitoring unit in order from the oldest packet stored in the buffer memory is encapsulated and output. The steps are provided.

  In this packet multiplex transmission apparatus and method, a second packet including a plurality of first packets is generated only when congestion occurs in the standby buffer unit, and no congestion occurs in the standby buffer unit Generates a second packet in which only one first packet is stored.

  According to the present invention, when congestion occurs, transmission efficiency can be increased by combining the first packets. Therefore, the first packet is caused by excessive accumulation of the first packets in the standby buffer unit when congestion occurs. On the other hand, when congestion does not occur, a certain amount of first packets are stored in the buffer memory to combine a plurality of first packets. Since there is no need to wait, signal transmission delay can be reduced. Accordingly, it is possible to realize a packet multiplex transmission apparatus and method that can reduce signal transmission delay while preventing packet discarding.

It is a block diagram which shows the structure of the network system by this Embodiment. It is a conceptual diagram which shows the structure of a MAC frame. It is a block diagram which shows schematic structure of a 1st packet multiplexing transmission apparatus. It is a characteristic curve figure which shows the relationship between packet length and transmission efficiency. It is a conceptual diagram which shows the structure of the encapsulated packet produced | generated at the time of occurrence of congestion in the standby buffer unit. It is a conceptual diagram which shows the structure of the encapsulated packet produced | generated when congestion does not generate | occur | produce in a standby buffer part. It is a block diagram which shows schematic structure of a standby buffer part. It is a conceptual diagram with which it uses for description of the 1st and 2nd threshold value. It is a flowchart which shows the process sequence of an encapsulated packet transmission process.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of Network System According to this Embodiment In FIG. 1, reference numeral 1 denotes a network system according to this embodiment as a whole. The network system 1 includes a first client device 2, a first packet multiplex transmission device 3, a transmission path 4, a second packet multiplex transmission device 5, and a second client device 6.

  The first client device 2 is a network node composed of a router or an L2 switch having an Ethernet (registered trademark) interface, an SDH / SONET interface, etc., and various communication standards transmitted from a personal computer (not shown). Is transferred to the first packet multiplexing transmission apparatus 3.

  The first packet multiplex transmission device 3 receives a non-packeted transmission signal (non-packet signal) such as SDH / SONET among a plurality of types of transmission signals transferred from the first client device 2 In the second packet multiplexing, the transmission signals are sequentially encapsulated, and the obtained individual packets (hereinafter referred to as encapsulated packets) are used as encapsulated packet signals via the transmission path 4 such as the Internet. Transmit to the transmission device 5. Further, when a transmission signal (packet signal) already packetized such as Ethernet (registered trademark) is given from the first client device 2, the first packet multiplex transmission device 3 uses the transmission signal as it is. The packet is sent to the second packet multiplex transmission device 5.

  The second packet multiplex transmission device 5 is a network node having the same configuration as the first packet multiplex transmission device, and separates the encapsulated packet from the encapsulated packet signal transmitted from the first packet multiplex transmission device 3. The original transmission signal is reconfigured by extracting and decapsulating the separated and encapsulated packet, and this is transmitted to the second client device 6 corresponding to the destination of the transmission signal. When the second packet multiplex transmission device 5 receives a transmission signal (packet signal) already packetized such as Ethernet (registered trademark) from the first packet multiplex transmission device 3, the second packet multiplex transmission device 5 directly transmits it. The data is sent to the second client device 6 corresponding to the destination of the transmission signal.

  The second client device 6 is a network node having the same configuration as that of the first client device 2, and transfers a transmission signal transmitted from the second packet multiplexing transmission device 5 to a destination node.

  When the network connecting the first client device 2 and the first packet multiplex transmission device 3 is Ethernet (registered trademark), the data is transmitted from the first client device 2 to the first packet multiplex transmission device 3. FIG. 2 shows the configuration of the MCA frame to be performed.

  As shown in FIG. 2, the MAC frame 7 includes an 8 [Byte] preamble 7A representing the beginning of the frame, a 6 [Byte] destination address 7B indicating the MAC address of the destination terminal of the MAC frame 7, and the MAC frame. 7 [Source] address 7C indicating the MAC address of the source terminal 7; 2 [Byte] Type / Length 7D indicating the frame length of the MAC frame 7; and variable in the range of 46 to 1500 [Byte] It consists of a long data area 7E and a checksum value 7F of 4 [Bytes]. The portion excluding the normal preamble 7A is counted in the effective packet range, and the frame length is 64 to 1518 [Byte].

(2) Configuration of First Packet Multiplexing Device FIG. 3 is a schematic diagram of a portion related to packet multiplexing in the first packet multiplex transmission device 3 (hereinafter referred to as a packet multiplexing portion). The configuration is shown. As is clear from FIG. 3, the first packet multiplex transmission apparatus 3 includes a plurality of low-speed interface units 10, a packet switch unit 11, and a plurality of transmission path interface units 12 as the packet multiplexing parts. Configured.

  The low-speed interface unit 10 includes a plurality of pre-multiplexing processing units 23 including a signal processing unit 20, a band control unit 21, and a standby buffer unit 22, and is transmitted from the first client device 2. The non-packet signal among the signals is packetized by the signal processing unit 20 of the corresponding pre-multiplexing processing unit 23. The packet thus obtained (hereinafter referred to as the original packet) is adjusted to a predetermined band by the band control unit 21 and then stored in the standby buffer unit 22.

  The standby buffer unit 22 has a role of temporarily storing original packets. The original packet stored in the standby buffer unit 22 is then encapsulated by adding the header and footer of the same standard, and then given to the multiplexing unit 24 as the above-described encapsulated packet. In 24, the packet is multiplexed with the encapsulated packet read from the other standby buffer unit 22 and then transmitted to the packet switch unit 11.

  The encapsulated packet transmitted to the packet switch unit 11 is then distributed to the transmission path interface unit 12 according to the destination by the packet switch unit 11 and transmitted as an encapsulated packet signal via the transmission path interface unit 12. It is output to the path 4 (FIG. 1).

  Here, in the first packet multiplexing transmission device 3 having such a configuration, traffic exceeding the transmission capacity may be concentrated in the standby buffer unit 22 and the multiplexing unit 24. When a traffic load exceeding the transmission capacity is applied to the standby buffer unit 22 and the multiplexing unit 24 (hereinafter, this state is referred to as congestion), the output waiting time of each original packet in the standby buffer unit 22 increases, The amount of original packets stored in the buffer unit 22 increases. In this case, the storage allowable amount of the standby buffer unit 22 is eventually exceeded, and the original packet is discarded.

  As a method of reducing the original packet discard due to such congestion, a method of increasing the storage capacity of the standby buffer unit 22 can be considered. However, this method increases hardware resources and is disadvantageous in terms of cost.

  As another method for reducing packet discard due to congestion, there is a method of transmitting a plurality of original packets combined.

  That is, in packet communication represented by Ethernet (registered trademark) or the like, it corresponds to a minimum no-communication section between packets (for example, at least 12 [Byte] called IFG (Inter Frame Gap) in Ethernet (registered trademark)). It is specified that a non-communication section) is provided. As the packet length is shorter, the ratio of the non-communication section in the transmission path increases, so that the transmission efficiency decreases. Conversely, the longer the packet length, the higher the transmission efficiency.

This transmission efficiency represents the ratio of effective data in the transmission path. The transmission efficiency is TE, and the total data amount of packets transmitted per predetermined time (hereinafter referred to as effective data amount) is D1 and IFG. The amount of data that can be transferred (hereinafter referred to as invalid data amount as appropriate) is D2, and
Is a numerical value calculated by.

  FIG. 4 shows an example of transmission efficiency in Ethernet (registered trademark). The effective data amount D1 is the effective packet length (64 [Byte] to 1518 [Byte]), and the invalid data amount D2 is the number of IFG data (12 [Byte]). ) As a graph. As is apparent from FIG. 4, there is a difference of about 22% in transmission efficiency between a 64 [Byte] long packet and a 1518 [Byte] long packet. That is, it can be seen that transmission efficiency can be improved by combining and transmitting a plurality of packets at the time of packet transmission.

  In relation to such a packet combination transmission method, the above-described Patent Document 1 discloses that the packet combination processing delay is reduced by executing the packet combination process even when the packet transmission timing is equal to or less than the prescribed number of packet combinations. Patent Document 2 discloses a method of constantly measuring the amount of traffic per unit time of traffic, predicting a waiting time in packet combination, and changing the number of packet combinations based on the prediction result. A method for reducing time is disclosed.

  However, even if any of these methods is adopted, there is a problem that a delay time of packet transmission cannot be eliminated because a waiting time is generated at the time of packet combining processing.

  In this case, in such a packet combining method, it is only necessary to increase transmission efficiency only when congestion occurs, and it is not always necessary to combine original packets. In addition, when congestion occurs, the amount of original packets stored in the standby buffer unit 22 increases. Therefore, it is determined that congestion has occurred when the retention amount of the original buffer in the standby buffer unit 22 increases. Can do. Therefore, only in this case, by performing a packet combining process for combining a plurality of original packets, it is possible to increase transmission efficiency and reduce the amount of original packets remaining in the standby buffer unit 22.

  Therefore, in the case of the present embodiment, in the standby buffer unit 22 of the first packet multiplex transmission device 3, when the retention of original packets exceeding a preset threshold (hereinafter referred to as the first threshold) occurs. One of the features is that the packet combining process is performed only on the packet buffer and the packet combining process is not performed when the retention amount of the original packet in the standby buffer unit 22 is less than the first threshold value.

  FIG. 5 shows a format example of the encapsulated packet 25 generated by combining a plurality of original packets OP (OP1 to OP3) by such packet combining processing. In the case of this embodiment, the encapsulated packet 25 has an encapsulated header 25A disposed at the beginning, and a combined presence / absence flag 25B disposed after the encapsulated header 25A. The combined presence / absence flag 25B is a flag indicating whether or not the encapsulated packet 25 includes a plurality of original packets OP. When the encapsulated packet 25 includes a plurality of original packets OP, “ When the encapsulated packet 25 includes only one original packet OP, it is set to “0”.

  A plurality of combined original packets OP are sequentially arranged after the combined presence / absence flag 25B. At this time, a combined header 25C is arranged at the head of each original packet OP. This combined header 25C is composed of a combined continuation flag 25CA indicating whether or not the original packet OP is the last original packet OP in the encapsulated packet 25, and information 25CB indicating the packet length of the original packet OP. Information. The combined continuation flag 25CA is set to “1” when the corresponding original packet OP is not the last original packet OP in the encapsulated packet 25, and the original packet OP is the last original packet in the encapsulated packet 25. If it is a packet OP, it is set to “0”. An encapsulation footer 25D is arranged at the end of the encapsulation packet 25.

  Accordingly, the second packet multiplex transmission apparatus 5 (FIG. 1) that has received the encapsulated packet 25 refers to the combined presence / absence flag 25B to determine whether or not the encapsulated packet 25 includes a plurality of original packets OP. When it is determined that the encapsulated packet 25 includes a plurality of original packets OP, the capsule packet 25 is referred to by referring to the combined header 25C arranged at the head of each original packet OP. Until the last original packet OP included in the combined packet 25, the original packets OP having the packet length included in the corresponding combined header 25C are sequentially separated and extracted.

  FIG. 7 shows a configuration example of the standby buffer unit 22 of the first packet multiplexing transmission apparatus for executing the packet combining process as described above. The standby buffer unit 22 includes a buffer memory 30 that temporarily stores an original packet OP given from the bandwidth control unit 21 and a packet combination that combines a plurality of original packets OP stored in the buffer memory 30 as necessary. Unit 31, a buffer monitoring unit 32 that monitors the total data amount of the original packet OP stored in the buffer memory 30, and a packet combination control unit 33 that controls the packet combination unit 31. Further, the packet combining unit 31 outputs a header / footer generating unit 34 that generates the encapsulation header 25A, the encapsulation footer 25D, the combined header 25C, and the like described above with reference to FIG. 5, and outputs of the buffer memory 30 and the header / footer generating unit 34. And a selector 35 that selectively outputs to the subsequent multiplexing unit 24 (FIG. 3).

  When the original packet OP is stored in the buffer memory 30 or the original packet OP is read from the buffer memory 30, the buffer memory 30 notifies the buffer monitoring unit 32 of the data amount of the original packet OP as a buffer monitoring signal. Yes.

  The buffer monitoring unit 32 predicts the retention amount of the original packet OP in the buffer memory 30 based on the buffer monitoring signal, and determines whether congestion has occurred based on the prediction result. Specifically, as shown in FIG. 8, the buffer monitoring unit 32 determines whether or not the retention amount of the original packet OP in the buffer memory 30 is equal to or greater than the above-described first threshold value. Then, the buffer monitoring unit 32 determines that congestion has occurred when the staying amount is greater than or equal to the first threshold, and when such staying amount is less than the first threshold, congestion has occurred. Judge that it is not.

  When the buffer monitoring unit 32 determines that congestion has occurred, the buffer monitoring unit 32 determines the number of original packets OP to be combined. Specifically, the buffer monitoring unit 32 determines the total amount of data when the original packets OP stored in the buffer memory 30 are combined in order from the oldest storage order in the buffer memory 30. The number of packets that is equal to or less than the second threshold value (the second threshold value is smaller than the first threshold value) is determined as the number of packets to be combined.

  For example, in the example of FIG. 8, the oldest original packet OP stored in the buffer memory 30 is first, the next oldest original packet OP is second, the next oldest original packet OP is third, and so on. Then, when the data amount is sequentially added from the first original packet OP, the total data amount is less than or equal to the second threshold until the Nth original packet OP. Therefore, in this case, the number of packets to be combined ( Hereinafter, this is referred to as the number of combined packets), which is “N”.

  Then, the buffer monitoring unit 32 combines the determination result as to whether or not the congestion determined as described above has occurred and the number of combined packets determined when it is determined that the congestion has occurred. To the packet combination control unit 33.

  On the other hand, the packet combining control unit 33 is given a packet transmission permission from the multiplexing unit 24 when the standby buffer unit 22 is ready to transmit the encapsulated packet 25. When receiving the packet transmission permission, the packet combination control unit 33 controls the header / footer generation unit 34, the buffer memory 30, and the selector 35 at predetermined timings based on the combination information given from the buffer monitoring unit 32. .

  Thus, under the control of the packet combination control unit 33, the header / footer generation unit 34, among the encapsulation header 25A, the combination presence / absence flag 25B, the combination header 25C, and the encapsulation footer 25D described above with reference to FIG. Necessary information is generated at a necessary timing and transmitted to the selector 35. Further, under the control of the packet combination control unit 33, the buffer memory 30 reads the oldest original packet OP among the original packets OP stored in the buffer memory 30 at a necessary timing and transmits it to the selector 35. Further, the selector 35 selectively outputs the outputs of the header / footer generation unit 34 and the buffer memory 30 to the subsequent multiplexing unit 24 under the control of the packet combination control unit 33.

  As a result, for example, when congestion occurs, the encapsulated packet 25 in the format described above with reference to FIG. 5 is generated and output to the multiplexing unit 24. When congestion does not occur, as shown in FIG. An encapsulation header 26A and a combined presence / absence flag 26B (the value of the combined presence / absence flag 26B is “0”) are added to the head of one original packet OP, and an encapsulation footer 26C is added to the tail of the original packet OP. The encapsulated packet 26 thus generated is generated and output to the multiplexing unit 24.

(3) Encapsulated packet transmission process FIG. 9 is a specific example of a series of processes (hereinafter referred to as encapsulated packet transmission process) executed in the standby buffer unit 22 in connection with the encapsulation of the original packet OP. A processing procedure is shown.

  This encapsulated packet transmission process is started when the transmission of the encapsulated packets 25 and 26 is given from the multiplexing unit 24 (FIG. 3) to the packet combination control unit 33 (FIG. 7). Based on the buffer monitoring signal given from the buffer memory 30, the retention amount of the original packet OP in the buffer memory 30 is acquired (SP1), and it is determined whether or not the acquired retention amount is equal to or greater than the first threshold (SP2). ).

  Obtaining a negative result in this determination means that congestion has not occurred. Thus, at this time, the buffer monitoring unit 32 notifies the packet combination control unit 33 of combination information indicating that congestion has not occurred.

  When the packet combination control unit 33 receives the combination information, the packet combination control unit 33 controls the header / footer generation unit 34 (FIG. 7), and the encapsulation header 26A and the combination presence / absence flag 26B (the combination presence / absence flag 26B described above with reference to FIG. And the selector 35 is controlled so that the encapsulation header 26A and the combined presence / absence flag 26B output from the header / footer generation unit 34 are sent to the multiplexing unit 24 (SP3). .

  Subsequently, the packet combination control unit 33 controls the buffer memory 30 to read out the oldest original packet OP among the original packets OP stored in the buffer memory 30 and controls the selector 35 to control the buffer. The original packet output from the memory is sent to the multiplexing unit (SP).

  Further, the packet combination control unit 33 controls the header / footer generation unit 34 to generate the encapsulation footer 26C described above with reference to FIG. 6, and also controls the selector 35 to output the header / footer generation unit 34. The encapsulation footer 26C is sent to the multiplexing unit 24 (SP).

  Through the above processing, an encapsulated packet 26 (FIG. 6) in which only the oldest original packet OP among the original packets OP stored in the buffer memory 30 is encapsulated is generated, and this is output from the selector 35 to the multiplexing unit 24. Will be.

  Then, the standby buffer unit 22 ends this encapsulated packet transmission process.

  On the other hand, obtaining a positive result in the determination at step SP2 means that congestion has occurred. Thus, at this time, the buffer monitoring unit 32 notifies the packet combination control unit 33 of information indicating that congestion has occurred and the number of packets to be combined (number of combined packets) at this time as combined information.

  The packet combination control unit 33 that has acquired the combination information acquires the number of combined packets from the combination information (SP6), and then controls the header / footer generation unit 34 to control the encapsulation header described above with reference to FIG. 25A and the combined presence / absence flag 25B (the value of the combined presence / absence flag 25B is “1”), and controls the selector 35 to output the encapsulated header 25A and the combined header output from the header / footer generating unit 34. The presence / absence flag 25B is sent to the multiplexing unit 24 (SP7).

  Further, the packet combination control unit 33 controls the header / footer generation unit 34 to generate the combined header 25C (FIG. 5) in which the combination continuation flag 25CA (FIG. 5) is set to “1”, and the selector 35 The combined header 25C is output to the multiplexing unit 24 (SP8). Further, the packet combination control unit 33 controls the buffer memory 30 to read out the oldest original packet OP among the original packets OP stored in the buffer memory 30 and controls the selector 35 to control the original packet OP. The packet OP is output to the multiplexing unit 24 (SP9).

  Thereafter, the packet combination control unit 33 determines whether or not the processing of step SP8 and step SP9 has been completed for the number of original packets OP that is one less than the number of combined packets notified as combination information (SP10). If the packet combination control unit 33 obtains a negative result in this determination, it returns to step SP8, and thereafter repeats the processing of step SP8 to step SP10.

  When the packet combination control unit 33 eventually obtains a positive result in step SP10 by completing the processing of step SP8 and step SP9 for the number of original packets OP that is one less than the number of combined packets notified as combination information, The header / footer generation unit 34 is controlled to generate a combined header 25C (FIG. 5) in which the combined continuation flag 25CA (FIG. 5) is set to “0”, and the selector 35 is controlled to perform this combination. The header 25C is sent to the multiplexing unit 24 (SP11).

  Further, the packet combination control unit 33 controls the buffer memory 30 to read out the oldest original packet OP among the original packets OP stored in the buffer memory 30 and controls the selector 35 to control the original packet OP. The packet OP is sent to the multiplexing unit 24 (SP12).

  Thereafter, the packet combination control unit 33 controls the header / footer generation unit 34 to generate the encapsulation footer 25D (FIG. 5), and also controls the selector 35 to transfer the encapsulation footer 25D to the multiplexing unit 25. Send out (SP13).

  Through the above processing, the encapsulated packet 25 described above with reference to FIG. 5 including the original packet OP of the number of combined packets acquired in step SP6 is generated, and this is sent from the selector 35 to the multiplexing unit 24.

  Then, the standby buffer unit 22 ends this encapsulated packet transmission process.

(4) Effects of this Embodiment As described above, in the network system 1 according to this embodiment, the original packet OP equal to or higher than the first threshold set in advance in the standby buffer unit 22 of the first packet multiplex transmission apparatus 3. When packet retention processing is performed only when congestion occurs (when congestion occurs), the retention amount of the original packet OP in the standby buffer unit 22 is less than the first threshold (when congestion does not occur). No packet combining process is performed for.

  Therefore, according to the present network system 1, when the congestion occurs, the transmission efficiency can be increased by combining the original packets OP. Therefore, the original packets OP are excessively accumulated in the standby buffer unit 22 when the congestion occurs. On the other hand, when congestion does not occur, it is necessary to wait for a certain amount of original packets OP to be accumulated in the buffer memory 30 for packet combining processing. Therefore, signal transmission delay can be reduced.

  Further, in the present network system 1, it is determined whether congestion has occurred based on the retention amount of the original packet OP in the standby buffer unit 22 without measuring the inflow and outflow amount of the original packet OP to the standby buffer unit 22. Therefore, the configuration of the first packet multiplex transmission device 3 can be simplified.

(5) Other Embodiments In the above-described embodiment, the case where the present invention is applied to the first packet multiplex transmission apparatus 3 configured as shown in FIG. 3 has been described. The present invention is not limited to this, and can be widely applied to packet multiplex transmission apparatuses having various configurations.

  In the above embodiment, the case where the first and second threshold values described above with reference to FIG. 8 are set to different values (first threshold value <second threshold value) has been described. For example, the first and second threshold values may be set to the same value.

  Further, in the above-described embodiment, the packet combination processing unit that encapsulates the original packet OP into the encapsulated packet based on the monitoring result of the buffer monitoring unit 32 includes the packet combination control unit 33, the header / footer generation unit 34, and Although the case where it is configured by the selector 35 has been described, the present invention is not limited to this, and various other configurations can be widely applied.

  The present invention relates to a packet multiplex transmission apparatus and method, and can be widely applied to packet multiplex transmission apparatuses having various configurations for encapsulating transmission signals.

  DESCRIPTION OF SYMBOLS 1 ... Network system, 3, 5 ... Packet multiplexing transmission apparatus, 4 ... Transmission path, 22 ... Standby buffer part, 23 ... Multiplexing pre-processing part, 24 ... Multiplexing part, 25, 26 ... Capsule Packet, 25B, 26B ... combined presence / absence flag, 25C ... combined header, 25CA ... combined continuation flag, 30 ... buffer memory, 31 ... packet combining unit, 32 ... buffer monitoring unit, 33 ... Packet combination control unit, 34... Header / footer generation unit, 35... Selector, OP.

Claims (12)

In a packet multiplex transmission apparatus that accommodates multiple types of transmission signals, performs packetization for non-packet signals, accommodates packet signals as they are, multiplexes and outputs each packet signal,
Multiplexing pre-processing for sequentially generating the first packet by sequentially packetizing the transmission signal or accommodating the packet signal as it is, and sequentially generating the second packet of the same standard by encapsulating the first packet And
A multiplexing unit that multiplexes the second packet generated by each of the multiplexing preprocessing units, and
The multiplexing preprocessing unit includes:
A signal processing unit that sequentially generates the first packet by sequentially packetizing each transmission signal or accommodating the packet signal as it is;
A standby buffer unit that temporarily stores the first packet and encapsulates the stored first packet to sequentially generate the second packet;
The standby buffer unit
A buffer memory for temporarily storing the first packet;
A buffer monitoring unit for monitoring the first retention amount in the buffer memory;
A packet combination processing unit that encapsulates the first packet into the second packet based on a monitoring result of the buffer monitoring unit;
The buffer monitoring unit
It is determined whether congestion has occurred based on the retention amount of the first packet in the buffer memory, and when it is determined that congestion has occurred, the number of packets of the first packet to be combined is determined. Calculate
The packet combining processing unit
When the buffer monitoring unit determines that no congestion has occurred, the oldest first packet of the first packets stored in the buffer memory is encapsulated and output. When the buffer monitoring unit determines that the packet has occurred, among the first packets stored in the buffer memory, the number of packets calculated by the buffer monitoring unit in order from the oldest packet A packet multiplex transmission apparatus characterized in that the first packets of minutes are combined and encapsulated for output. The buffer monitoring unit
Based on the data amount of the first packet stored in the buffer memory and the data amount of the first packet read from the buffer memory, the retention amount of the first packet in the buffer memory The packet multiplex transmission apparatus according to claim 1, wherein: The buffer monitoring unit
3. The packet multiplexing according to claim 2, wherein congestion is determined when a retention amount of the first packet in the buffer memory exceeds a predetermined first threshold value. Transmission equipment. The buffer monitoring unit
The number of packets in which the total amount of data when the storage order in the buffer memory is combined in order from the oldest is determined to be the number of packets to be combined is determined as the number of packets to be combined. Item 4. The packet multiplex transmission device according to Item 3. The packet combining processing unit
When combining a plurality of the first packets, a flag indicating whether the first packet is the last first packet in the second packet at the head of the first packet; The packet multiplexing transmission apparatus according to claim 1, wherein a header including a packet length of the first packet is added. The second packet is:
The packet multiplex transmission apparatus according to claim 1, further comprising a second flag indicating whether or not the second packet includes a plurality of first packets. In a packet multiplex transmission method that accommodates multiple types of transmission signals, performs packetization on non-packet signals, accommodates packet signals as they are, multiplexes and outputs each packet signal,
Multiplexing pre-processing for sequentially generating the first packet by sequentially packetizing the transmission signal or accommodating the packet signal as it is, and sequentially generating the second packet of the same standard by encapsulating the first packet And
A multiplexing unit that multiplexes the second packet generated by each of the multiplexing preprocessing units, and
The multiplexing preprocessing unit includes:
A signal processing unit that sequentially generates the first packet by sequentially packetizing each transmission signal or accommodating the packet signal as it is;
A standby buffer unit that temporarily stores the first packet and encapsulates the stored first packet to sequentially generate the second packet;
The standby buffer unit
A buffer memory for temporarily storing the first packet;
A buffer monitoring unit for monitoring the first retention amount in the buffer memory;
A packet combination processing unit that encapsulates the first packet into the second packet based on a monitoring result of the buffer monitoring unit;
The buffer monitoring unit determines whether congestion has occurred based on the retention amount of the first packet in the buffer memory, and determines that the congestion has occurred, the first to be combined A first step of calculating the number of packets of
If the packet monitoring unit determines that no congestion has occurred, the packet combination processing unit encapsulates the oldest first packet among the first packets stored in the buffer memory. When the buffer monitoring unit determines that congestion has occurred, the buffer monitoring unit sequentially starts with the oldest one of the first packets stored in the buffer memory. A second step of combining, encapsulating, and outputting the first packets for the number of packets calculated in step (1). In the first step, the buffer monitoring unit includes:
Based on the data amount of the first packet stored in the buffer memory and the data amount of the first packet read from the buffer memory, the retention amount of the first packet in the buffer memory The packet multiplexing transmission method according to claim 7, wherein the packet multiplexing transmission method is predicted. In the first step, the buffer monitoring unit includes:
9. The packet multiplexing according to claim 8, wherein congestion is determined when a retention amount of the first packet in the buffer memory is equal to or greater than a predetermined first threshold value. Transmission method. In the first step, the buffer monitoring unit includes:
The number of packets in which the total amount of data when the storage order in the buffer memory is combined in order from the oldest is determined to be the number of packets to be combined is determined as the number of packets to be combined. Item 10. A method for controlling a packet multiplexing transmission apparatus according to Item 9. In the second step, the packet combination processing unit includes:
When combining a plurality of the first packets, a flag indicating whether the first packet is the last first packet in the second packet at the head of the first packet; The packet multiplex transmission method according to claim 7, wherein a header including a packet length of the first packet is added. The second packet is:
The packet multiplex transmission method according to claim 7, further comprising a second flag indicating whether or not the second packet includes a plurality of first packets.