JP2008227623A - Packet transfer device and packet transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a receiver side to select a packet without instantaneous disconnection without processing a packet to be transmitted, in a technique for transmitting packets to a plurality of paths and allowing the receiver side to select one packet. <P>SOLUTION: A packet transfer device on a transmitter side sequentially forms packet frames composed of a predetermined number of packets or packets for a predetermined time in the packets to be sequentially inputted, inserts a synchronous packet including order identification information into each of the packet frames, and duplicates the packet frames and transmits them to a plurality of systems of transmission paths. A packet transfer device on a receiver side identifies the same packet frames among a plurality of systems by using the order identification information of the synchronous packet included in each of the packet frames to be received from the plurality of systems of transmission paths, determines the difference in delay among the plurality of systems, and uses the difference in delay to select the packet frame in one system from among the plurality of packet frames adjusted in delay using the difference in delay and outputs the selected packet frame to a lower side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention transmits an input packet through a plurality of transmission lines in a packet transfer network such as an IP network or an Ethernet network, and selects a packet on one transmission line without interruption in the receiving side. The present invention relates to a technique for transmitting downstream in the order of packets.

  In a conventional packet transfer network, as a failure detection / recovery technique for achieving high reliability of packet transfer, for example, STP (Spanning Tree Protocol) (Non-Patent Document 1), RSTP (Rapid Spanning Tree Protocol) (Non-Patent Document 2) ), Link Aggregation (Non-Patent Document 3) and the like. Further, there are FRR (Fast ReRoute), RPR (Resilient Packet Ring) (Non-patent Document 4) and the like as techniques for performing failure detection and recovery at higher speed.

  These technologies determine the packet transfer path from multiple transmission paths based on the priority of primary, secondary, etc., and restore the communication by switching from the transfer path that failed at the time of failure detection to another transfer path. Technology.

  Further, there is a technique described in Patent Document 1 as a packet transfer technique for the purpose of failure recovery without packet loss. In this technology, an order identifier for identifying the order is inserted into a packet, the packet is copied, a plurality of packets are generated, these are sent to a plurality of paths, and the reception side receives from a plurality of paths. The order and identity of the packets are identified based on the order identifier, and one of the same packets is transferred downstream according to the order of the packets.

In the specification and claims of the present application, the term “packet” is used in a broad sense including the meaning of “frame” transferred in the layer 2 network.
IEEE 802.1D Spanning Tree Protocol (STP) IEEE 802.1w Rapid Spanning Tree (RSTP) Link Aggregation IEEE802.17 Resilient Packet Ring (RPR) JP 2006-174406 A

  The time required for failure detection and recovery by conventional STP, RSTP, FRR, RPR, etc. is about 50 msec at the shortest. Therefore, for applications that require highly reliable lines that do not allow packet loss, such as video communication. There's a problem.

  In addition, in the technique described in Patent Document 1, an order area such as a sequence number or a time stamp is added to a packet, so an overhead area is required, and a maximum transferable packet length (MTU: Maximum Transfer Unit) is limited. There is a problem that it cannot be applied to a transmission line.

  Also, especially in IP networks, etc., when packets are transferred, packet arrival timing fluctuations and packet arrival order may be reversed, which may affect downstream applications that use packets. It is desired to suppress such fluctuations and correct order inversion.

  The present invention has been made in view of the above points. In the technique of sending a packet to a plurality of routes and selecting a packet of one route on the receiving side, the receiving side does not process the packet to be sent. It is an object of the present invention to provide a technique that enables packet selection by instantaneous interruption. A further object of the present invention is to provide a technique for transmitting packets downstream according to the input order on the packet transmission side without processing the packets to be transmitted. A further object of the present invention is to provide a technique for absorbing fluctuations in packet arrival timing and transferring each packet downstream at the timing when the packet is input on the transmission side.

  The above-described problems include a packet transmission unit that duplicates an input packet and sends the packet to a plurality of transmission paths, and receives a packet from a plurality of transmission paths. A packet transfer device comprising: a packet receiving means for selecting and sending downstream; wherein the packet transmission means sequentially sends a packet corresponding to a predetermined number of predetermined packets or a predetermined time in a packet frame Synchronization packet generation / insertion means for inserting a synchronization packet including sequence identification information in each packet frame, and packet frame transmission means for duplicating the packet frame and transmitting the packet frame to a plurality of transmission paths. The receiving means uses a plurality of synchronization packet sequence identification information included in each packet frame received from a plurality of transmission paths. A delay difference determining means for identifying the same packet frame between the systems and determining a delay difference of the same packet frame between a plurality of systems; and a plurality of systems using the delay difference obtained by the delay difference determining means. Delay adjusting means for adjusting the delay of the packet frame between them, packet frame selecting means for selecting one packet packet from a plurality of packet frames adjusted in delay by the delay adjusting means, and the packet This is solved by a packet transfer device comprising: packet frame sending means for sending the packet frame selected by the frame selecting means downstream.

  The synchronization packet generation / insertion means in the packet transmission means may include an error detection code calculated from a packet included in the packet frame in the synchronization packet. In this case, the packet reception means is included in the synchronization packet. Error detection means for detecting an error of the packet frame using an error detection code to be detected, and the packet frame selection means selects a packet frame of a system other than the packet frame system in which an error is detected by the error detection means. select.

  Further, the packet frame selection means may include an early arrival determination means for determining the earliest arrival packet frame among the same packet frames among a plurality of systems. The determined packet frame is sent downstream.

  The synchronization packet generation / insertion unit in the packet transmission unit may calculate a feature value of each packet included in the packet frame, and include the feature value in the synchronization packet in the order of the packets included in the packet frame. In this case, the packet frame sending means in the packet receiving means calculates the feature value of each packet in the received packet frame, and compares the feature value with the feature value included in the synchronization packet, thereby Means are provided for sending each packet downstream in the order of the feature values included in the packet.

  The synchronous packet generation / insertion unit in the packet transmission unit calculates a packet interval time between the packet and the previous packet for each packet included in the packet frame, and is included in the packet frame. Each packet interval time may be included in the synchronization packet in the order of the packets. In this case, the packet frame sending means in the packet receiving means, for each packet included in the received packet frame, And means for sending the packet to be sent downstream after a packet interval corresponding to the packet to be sent after sending the previous packet.

  The packet frame sending means in the packet sending means may include means for adding a delay to the packet frame of one of the plurality of systems.

  In addition, according to the present invention, there is provided a packet transfer apparatus comprising: a packet transmission unit that transmits an input packet to a transmission line; and a packet reception unit that receives a packet from the transmission line and transmits the received packet downstream. The packet transmission means sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, calculates a feature value of each packet included in the packet frame, and Synchronous packet storing each feature value in the order of packets included in the packet frame, generating synchronous packet for inserting the synchronous packet into the packet frame, and packet frame transmission for transmitting the packet frame to the transmission path Means for receiving the packet frame received from the transmission path. Means for acquiring a synchronization packet including a feature value from, and calculating a feature value of each packet in the packet frame, and comparing the feature value with a feature value included in the synchronization packet, thereby including the synchronization packet And a means for sending each packet downstream in the order of the feature values to be provided.

  Furthermore, according to the present invention, there is provided a packet transfer apparatus comprising: a packet transmission unit that transmits an input packet to a transmission line; and a packet reception unit that receives a packet from the transmission line and transmits the received packet downstream. The packet transmitting means sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, and for each packet included in the packet frame, the packet is immediately preceding the packet. Synchronous packet generation / insertion that calculates a packet interval time between each packet, generates a synchronization packet storing each packet interval time in the order of packets included in the packet frame, and inserts the synchronization packet into the packet frame Means, and packet frame sending means for sending the packet frame to a transmission line; The packet receiving means includes means for obtaining a synchronization packet including a packet interval time from a packet frame received from a transmission path, and for each packet included in the packet frame, a packet preceding the packet to be transmitted. And a means for sending the packet to be sent downstream after a packet interval time corresponding to the packet to be sent after sending the packet.

  According to the present invention, in a technique for sending a packet to a plurality of routes and selecting a packet of one route on the receiving side, it is possible to select a packet without interruption without processing the packet to be sent. Technology can be provided. Further, according to the present invention, it is possible to provide a technique for transmitting packets downstream according to the input order on the packet transmission side without processing the packets to be transmitted. Furthermore, according to the present invention, it is possible to provide a technique for absorbing fluctuations in packet arrival timing and transferring each packet downstream at the timing when the packet is input on the transmission side.

  Embodiments of the present invention will be described below with reference to the drawings.

(Overview)
FIG. 1 is a schematic configuration diagram of a packet transfer system according to the present embodiment. As shown in FIG. 1, the packet transfer system according to the present embodiment has a configuration in which a packet transfer device 1 and a packet transfer device 3 are connected to a packet transfer network 5. The packet transfer network 5 is a network for transferring packets such as an IP network and an Ethernet network.

  Each of the packet transfer apparatuses 1 and 3 has a function part for transmitting a packet and a function part for receiving a packet. In the following description, the packet transfer apparatus 1 is a transmission side and the packet transfer apparatus 2 is a reception side. explain. For example, a user network is connected to each of the packet input side (referred to as upstream) of the packet transfer apparatus 1 and the packet output side (referred to as downstream) of the packet transfer apparatus 3.

  In this packet transfer system, a packet of a predetermined number of packets or a packet for a predetermined time is sequentially transmitted as virtual frames (hereinafter referred to as packet frames) for packets that the packet transfer apparatus 1 sequentially receives from upstream. ) And a synchronization packet with sequence identification information (sequence number or the like) for identifying the sequence of the packet frame is generated and inserted into the packet frame. Note that various information such as a packet characteristic value and a packet interval time is attached to the synchronization packet. Details will be described later.

  The packet transfer apparatus 1 duplicates the packet frame in which the synchronization packet is inserted, and sends out the same two packet frames to different transmission paths 7 and 9, respectively. The transmission paths 7 and 9 are preferably physically different transmission paths, but may be physically the same but logically different transmission paths. Hereinafter, the system corresponding to the transmission path 7 is referred to as 0 system, and the system corresponding to the transmission path 9 is referred to as 1 system. In the present embodiment, the case of two systems of system 0 and system 1 will be described, but the present invention can be applied to systems with more than two systems.

  The packet transfer apparatus 3 on the receiving side receives the packet frame transmitted via the transmission path 7 and the packet frame transmitted via the transmission path 9. Then, the packet transfer apparatus 3 adjusts the delay difference between the systems using the sequence identification information attached to the synchronization packet included in the packet frame, selects one system packet without interruption, and sends it downstream. To do. In addition, using the feature value and packet interval time information included in the synchronization packet, the packet transfer apparatus 1 can send the packet downstream in the same order and timing as the order and timing of the packet received from the upstream. It is.

(About synchronous packets)
Next, the concept of synchronous packet generation will be described with reference to FIG. FIG. 2 shows a concept in which packets are sequentially input from the upstream to the packet transfer apparatus 1 and a synchronous packet (hatched) is inserted.

  In the example shown in FIG. 2, a packet frame is generated every three packets, and a synchronization packet is generated and inserted for each packet frame. That is, the synchronization packet 2 is generated for the packets 1 to 3 and inserted between the packets 3 and 4, the synchronization packet 3 is generated for the packets 4 to 6 and inserted between the packets 6 and 7. Has been.

  The synchronization packet is given its own sequence number. Further, the synchronization packet stores the feature value of each packet of the packet frame corresponding to the synchronization packet and the time interval between the packets in the order of each packet as necessary. The characteristic value of the packet is, for example, a value obtained by performing a hash operation on the packet. The interval time between packets is a so-called interframe gap (IFG). For example, in FIG. 2, the packet interval time 1 is the time interval between the packet 0 and the packet 1 that precedes the packet 1. Here, the time interval is before the synchronization packet is inserted. For example, the packet interval time 1 is the time from the arrival of the packet 0 from the upstream until the arrival of the packet 1 from the upstream. .

  FIG. 3 is a diagram showing an example of the synchronization packet in detail. FIG. 3 shows an example in which the synchronization packet is an IP packet.

  “Type” shown in FIG. 3 is information indicating the type of the synchronization packet. For example, the type is classified depending on whether or not the feature value and the packet interval are included. The synchronization frame sequence number is the above-described order identification information. The time information is an absolute time when the synchronization packet is generated. By using this absolute time, the receiver can grasp the absolute delay.

  The number of packets in the frame is the number of packets included in the packet frame (received from upstream), and the byte length in the frame is the total byte length of these packets. The user frame error detection code is an error detection code calculated from the packet in the packet frame. The transmission ID is, for example, user identification information, and the information type is, for example, the type of information (video or the like) carried by the packet. Various information can be set for the transmission ID and information type as needed for operation.

  The feature value and the packet interval are as described above. In the example of FIG. 3, the packet interval is added after the feature value, but the feature value and the packet interval may be alternately arranged. The frame payload error detection code is an error detection code of the synchronization packet itself.

(About device configuration)
FIG. 4 shows a configuration example of the packet transfer apparatus 10 in the present embodiment. The packet transfer apparatus 10 is assumed to be connected to the 0-system transmission path 7 and the 1-system transmission path 9 shown in FIG. As shown in FIG. 4, the packet transfer apparatus 10 according to the present embodiment includes a transmission function unit 12 that transmits a packet input from upstream to two transmission paths, and one of the packets received from the two transmission paths. And a reception function unit 14 for selecting and sending downstream packets. When viewed from one packet transfer apparatus 10, the upstream indicates the user network side when receiving a packet from the user network, and the downstream indicates the user network side when transmitting the packet to the same user network.

(About the transmission function part)
The transmission function unit 12 includes a packet reception unit 21, a synchronous packet generation / insertion unit 23, a packet copy unit 25, and packet transmission units 27A and 27B.

  The packet receiving unit 21 receives a packet transmitted from upstream, and sequentially sends the packet to the synchronous packet generation / insertion unit 23. The synchronization packet generation / insertion unit 23 inserts a synchronization packet in packet frame units and passes the packet frame to the packet copy unit 25. The packet copy unit 25 copies the packet, generates two identical packets, and passes them to the packet transmission units 27A and 27B. Each of the packet transmission units 27A and 27B sends the packet to the transmission lines 7 and 9. At this time, a route identifier is appropriately assigned.

  Next, the synchronization packet generation / insertion unit 23 in the transmission function unit 12 will be described in more detail. FIG. 5 shows a configuration diagram of the synchronization packet generation / insertion unit 23. As shown in FIG. 5, the synchronization packet generation / insertion unit 23 includes a timing extraction unit 231, a packet feature extraction unit 233, a synchronization information recording unit 235, a synchronization information generation unit 237, and a synchronization packet insertion unit 239.

  The timing extraction unit 231 is a functional unit that measures the packet interval time described above. That is, the interval time between the Nth packet and the (N + 1) th packet is counted and stored in the synchronization information recording unit 235 as the packet interval time of the (N + 1) th packet. The packet feature extraction unit 233 extracts the feature value of the packet and records it in the synchronization information recording unit 235.

  Since the synchronization packet is inserted / transmitted between packets at a constant number of packets or at a constant time, the packet interval and feature value stored in the synchronization packet are stored in the synchronization information recording unit 235 for a certain period.

  The synchronization information generation unit 237 acquires the packet interval time and the packet characteristic value from the synchronization information recording unit 235 and generates other information (time information, sequence number, packet error detection code, etc.) to be stored in the synchronization packet. Then, a synchronization packet is generated using them. The generated synchronization packet is inserted between packets corresponding to the synchronization packet by the synchronization packet insertion unit 239.

  In synchronization packet generation, if the synchronization packet exceeds the maximum packet length that can be transferred, the synchronization packet may be divided and inserted. On the receiving side, the divided synchronization packets are combined and processed as one synchronization packet.

(Reception function part)
The reception function unit 14 includes packet reception units 31A and 31B, a failure detection unit 33, a delay difference determination unit 35, a delay difference adjustment unit 37, a packet frame selection unit 39, and a packet transmission unit 41.

  The packet receiving units 31A and 31B receive packets from the transmission paths 7 and 9, respectively. Each system packet is input to the failure detection unit 33.

  The failure detection unit 33 identifies the packet frame using the packet number information of the synchronization packet in each system, performs error detection on a packet frame basis using the error detection code, and sends the detection result to the packet frame selection unit 39. Notice. The failure detection unit 33 has a function of detecting a failure in the transmission path by a method other than the method using the error detection code of the synchronization packet. It is good also as notifying.

  The delay difference determination unit 35 determines the packet frame delay difference between the systems using the arrival times of the synchronization packets having the same order identification information. Then, the delay difference adjustment unit 37 adjusts the delay between the systems using the delay difference determination result in the delay difference determination unit 35, and sends the packet frame in which the delay is adjusted to the packet frame selection unit 39. The packet frame selection unit 39 selects one of the two systems in which no error is detected in the packet frame, and transmits the packet of that system to the packet transmission unit 41.

  The packet transmitting unit 41 corrects the order of packets and adjusts so that the time interval of packets to be transmitted is the time interval when packets are input from upstream, if necessary, and transmits the packets.

  FIG. 6 shows a configuration example of the delay difference determination unit 35. As illustrated in FIG. 6, the delay difference determination unit 35 includes a time recording unit 351 and a time difference calculation unit 353. The time recording unit 351 records the arrival time of the synchronization packet in each system in association with the order identification information. Then, the time difference calculation unit 353 calculates the difference between the arrival time in the 0 system and the arrival time in the 1 system for the same order identification information, and outputs it as a delay difference. In addition, the arrival time and the sequence number are recorded in the time recording unit 351 for a predetermined number of synchronization packets in each system, and the time difference calculation unit 353 calculates the average arrival time difference for the same synchronization packet. It may be output as a delay difference. The determination of the delay difference by the delay difference determination unit 35 may be performed for each synchronization packet or may be performed at regular time intervals.

  Note that the delay difference determination unit 35 may not use the synchronization packet of the packet frame having the error in the delay difference determination by using the packet frame error detection result in the failure detection unit 33.

  FIG. 7 shows a configuration example of the delay difference adjustment unit 37. As shown in FIG. 7, the delay difference adjusting unit 37 includes a packet storage unit 371A (memory or the like) that temporarily stores 0-system packets, a packet storage unit 371B that temporarily stores 1-system packets, and a system with a smaller delay. A delay insertion unit 373 that inserts a delay (referred to as an early arrival system). The delay amount inserted by the delay insertion unit 373 is the delay difference notified from the delay difference determination unit 35, but a smaller delay may be inserted or no delay may be inserted. These can be changed by setting.

  By inserting the delay difference notified from the delay difference determination unit 35 into the early arrival system, there is no delay difference between the 0 system and the 1 system, and both systems are synchronized. Further, by using the average value of the delay differences using a plurality of synchronization packets, it is possible to avoid the delay from fluctuating greatly in a short time due to fluctuations in the packet frame.

  FIG. 8 shows a configuration example of the packet frame selection unit 39. The packet frame selection unit 39 includes a selection instruction unit 391, a selection unit 393, and an early arrival determination unit 395. Upon receiving the error detection information from the failure detection unit 33, the selection instruction unit 391 sends an instruction to the selection unit 393 to select the system that has no abnormality. The selection unit 393 selects and outputs one system packet frame in accordance with an instruction from the selection instruction unit 391.

  If synchronization is established between the systems in the packet frame output from the delay difference adjustment unit 37, the system can be switched without packet loss by switching the system to the normal system when an abnormality is detected in the selected system. .

  The switching timing based on the error detection of the packet frame is the timing at which the same packet frame in the other system is output from the packet frame selection unit 39 at the timing when the failure detection unit 33 determines that the packet frame has an error. It is only necessary to calculate and use the timing. The timing can be obtained from the delay difference.

  When the delay difference adjustment unit 37 does not adjust the delay difference, or when the delay difference is set so as not to insert a delay in the early arrival system so that both systems can be synchronized (when the delay difference between both systems is larger than a predetermined value, etc.) ) Causes a time difference for the same packet frame to arrive at the packet frame selector 39. For example, in such a case, from the viewpoint of reducing the delay, an early arrival determination unit 395 is provided as shown in FIG. 8, the early arrival determination unit 395 determines an early arrival packet frame, and selects the packet frame system. The selection unit 393 is instructed. In this way, by combining the delay difference adjustment and the early arrival system selection, it becomes possible to perform system switching without greatly changing the delay.

  There are various methods for determining early arrival. For example, the following method can be used. The early arrival determination unit 395 has a function of recording the order identification information (sequence number) of synchronization packets sent downstream, and whether or not the order identification information of synchronization packets sequentially received from each system has already been recorded. If it is already recorded, the packet frame of the synchronization packet is not transmitted. If it is not recorded, it is determined that the packet frame corresponding to the synchronization packet is early arrival, and it is output and its order Record identification information. In addition, it is possible to perform early arrival determination for each packet by using feature values for early arrival determination.

  When the early arrival system is selected, if an abnormality is detected in the early arrival system packet frame, for example, the early arrival system determination unit 395 is notified together with the order identification information, and the early arrival system determination unit In step S395, the selection unit 393 is instructed to select the next received packet frame of the same order identification information without selecting the packet frame including the abnormality.

  Further, in the case of an abnormality such that the early arrival packet frame itself does not arrive, since the late arrival packet frame arrives early, the early arrival determination unit 395 selects the system packet frame.

  Now, after selecting the late arrival system due to an early arrival system abnormality, if the early arrival system recovers and a packet frame arrives, there is a possibility that a burst output corresponding to the path delay may occur or the order of the packet frames may be changed. is there.

  In addition, when packet order changes occur in both systems, an error in the packet frame is detected in both systems. In such a case, for example, an early arrival system is used without switching the systems. Leave selected.

  As described above, a packet whose order has been changed may arrive at the packet transmission unit 41. In addition, fluctuation may occur in the arrival timing of the packet, which may be undesirable for downstream applications.

  The packet transmission unit 41 includes means for solving such a problem. FIG. 9 shows a configuration example of the packet transmission unit 41.

  The packet transmission unit 41 in the example illustrated in FIG. 9 includes a storage calculation unit 411, a synchronization packet acquisition unit 413, a feature value acquisition unit 415, a packet interval time acquisition unit 417, a packet / feature value storage unit 419, a packet search unit 421, and A packet interval time adjustment unit 423 is provided.

  The storage calculation unit 411 calculates a feature value for each packet included in the packet frame received from the packet frame selection unit 39 by the same method as the feature value calculation at the time of synchronization packet generation, and stores the packet / feature value in association with the packet. Stored in the unit 419. In addition, the synchronization packet acquisition unit 413 acquires a synchronization packet from the received packet frame, and the feature value acquisition unit 415 acquires feature values in order from the synchronization packet acquired by the synchronization packet acquisition unit 413. The packet interval time acquisition unit 417 acquires a packet interval time corresponding to the feature value acquired by the feature value acquisition unit 415. That is, the packet interval time acquired here is a time interval between the packet immediately before the packet corresponding to the feature value acquired by the feature value acquisition unit 415 and the packet corresponding to the feature value.

  The feature value acquisition unit 415 inputs the feature value to the packet search unit 421. The packet search unit 421 searches the packet / feature value storage unit 419 and acquires a packet corresponding to the input feature value. The packet interval time adjustment unit 423 receives the packet interval time corresponding to the feature value input to the packet search unit 421 from the packet interval time acquisition unit 417. The packet interval time adjustment unit 423 outputs the packet searched by the packet search unit 421 after the packet interval time after outputting the previous packet. When a packet can be searched after the packet interval time after outputting the previous packet, the packet is output immediately.

  FIG. 10 is a diagram for explaining a specific example of the operation of the packet transmission unit 41. As shown in FIG. 10, it is assumed that packet 1, feature value storage unit 419 stores packet 1, feature value 1, packet 3, feature value 3, packet 2, and feature value 2 in this order. Assume that packet 0 is output before packet 1. The synchronization packet acquired by the synchronization packet acquisition unit 413 includes feature values 1, 2, and 3 and packet interval times 1, 2, and 3 shown in FIG.

  First, the packet / feature value storage unit 419 is searched based on the feature value 1 included in the synchronization packet, the packet 1 is extracted, and the packet 1 is transmitted after “packet interval time 1” time of the packet 0 output. Similarly, the packet / feature value storage unit 419 is searched based on the feature value 2 included in the synchronous packet, the packet 2 is output, and the packet 2 is output after “packet interval time 2” time of the packet 1 output. . Then, the packet / feature value storage unit 419 is searched based on the feature value 3 included in the synchronization packet, the packet 3 is output, and the packet 3 is output after “packet interval time 3” time of the packet 3 output. Thus, even if the order of the packets is changed, the packets can be output in the correct order by sequentially using the feature values included in the synchronization packet. Also, by using the packet interval time, packets can be output at the same interval as the packet interval input from the upstream, and the influence of fluctuations in the network and the like can be absorbed. Since the synchronization packet includes an order identification number, the packet order can be corrected even if the packet order is changed between packet frames.

  The packet transmission unit 41 may have any configuration as long as the operation shown in FIG. 10 can be performed. For example, a configuration as shown in FIG. 11 is also possible.

  In this example, the packet transmission unit 41 includes a storage calculation unit 431, a synchronous packet acquisition unit 433, a feature value acquisition unit 435, a packet interval time acquisition unit 437, a packet storage memory 439, a feature value / address storage search unit 441, and a packet An interval time adjustment unit 443 is provided.

  The storage calculation unit 431 stores each packet included in the packet frame received from the packet frame selection unit 39 in the packet storage memory 439, calculates a feature value of the packet, and corresponds the feature value to the feature value. The packet is stored in the feature value / address storage search unit 441 together with the address of the packet storage memory 439 storing the packet.

  Further, the synchronization packet acquisition unit 433 acquires a synchronization packet from the received packet frame, and the feature value acquisition unit 435 acquires feature values in order from the synchronization packet acquired by the synchronization packet acquisition unit 433. Further, the packet interval time acquisition unit 437 acquires a packet interval time corresponding to the feature value acquired by the feature value acquisition unit 435.

  The feature value acquisition unit 435 inputs the feature value to the feature value / address storage search unit 441. The feature value / address storage search unit 435 outputs an address corresponding to the input feature value. The address is input to the packet interval time adjustment unit 443. The packet interval time adjustment unit 443 also acquires the packet interval time from the packet interval time acquisition unit 437. The packet interval time adjustment unit 443 outputs the packet immediately before the packet corresponding to the address input from the feature value / address storage search unit 441, and then sets the address after the packet interval time to the packet storage memory. To output a packet corresponding to the address. For example, an associative memory can be used as the feature value / address storage search unit 441.

  It should be noted that a function related to packet interval time adjustment in the packet transmission unit 41 may be provided as necessary. When a packet whose packet order is adjusted is received and there is no need to correct the order, the packet interval time adjusting unit 50 can be used as the packet transmitting unit 41 as shown in FIG.

  The packet interval time adjustment unit 50 illustrated in FIG. 12 includes a feature value calculation unit 52, a packet interval time acquisition unit 54, and an adjustment unit 56. The feature value calculation unit 52 calculates the feature value of each packet in the input packet frame and sequentially passes it to the packet interval time acquisition unit 54. The packet interval time acquisition unit 54 acquires a synchronization packet corresponding to the packet frame, acquires a packet interval time corresponding to the feature value passed from the feature value calculation unit 52, and passes it to the adjustment unit 56. The adjustment unit uses the packet interval time corresponding to the input packet, outputs the packet immediately before the packet, and then outputs the packet after the packet interval time.

  Note that the feature value may not be used if there is another means for identifying the packet and the corresponding packet interval.

(About time diversity)
In the present embodiment, it is possible to realize time diversity by adding a delay to the packet of one of the packet transmission units in the packet transfer apparatus 10. In this case, the packet transmission unit is provided with a buffer memory, and a delay is added by delaying the reading of the buffer memory. A case where time diversity is possible in this way will be described with reference to the system configuration diagram of FIG.

  In this embodiment, two transmission lines 7 and 9 are used, but these may be physically the same. For example, this is a case where two paths are logically provided in one optical fiber and used as two transmission lines. Even in such a case, the optical fiber often has a working system and a standby system that are physically different, and this case is assumed in this example.

  As shown in FIG. 13, the packet transfer device 1 and the packet transfer device 3 are connected by a 0-system transmission line 7 and a 1-system transmission line 9. The 0-system transmission line 7 and the 1-system transmission line 9 are normally set to the physical transmission line 100 which is the active system. However, when the physical transmission line 100 fails, it is switched to the physical transmission line 200, and the packet transfer device The 0-system transmission line 7 and the 1-system transmission line 9 connecting the 1 and the packet transfer apparatus 3 pass through the physical transmission line 200.

  Assume that the switching time from the physical transmission path 100 to the physical transmission path 200 is, for example, 50 ms. In addition, a delay of, for example, 100 ms is inserted into the 1-system packet transmission unit in the packet transfer apparatus 1 on the transmission side. By doing so, as shown in FIG. 14, for example, there is a failure in the physical transmission path 100 before and after the timing at which the packet frame 1 is output from the 0 system, and the packet frame 1 from the 0 system packet transmitting unit. Even after loss, the packet frame 1 from system 1 output after 100 ms is transmitted after switching to the physical transmission path 200 after 50 ms.

  In this case, if the packet transfer apparatus 3 on the receiving side selects the 0-system packet frame before the failure of the physical transmission line 100, the packet loss is performed by switching to the 1-system by the system selection process described so far. Packets can be output.

  Note that the function of the packet transmission unit 41 in the packet reception function unit 14 described in the present embodiment can be applied not only to the packet transfer device 10 as long as it is a device that receives a packet frame including a synchronization packet. is there. As an apparatus including such a function of the packet transmission unit 41, for example, there is the following packet transfer apparatus.

  The packet transfer apparatus is a packet transfer apparatus including a packet transmission unit that transmits an input packet to a transmission path, and a packet reception unit that receives a packet from the transmission path and transmits the received packet downstream. The packet transmitting means sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, calculates a feature value of each packet included in the packet frame, and adds the packet frame to the packet frame. Generating a synchronization packet storing each feature value in the order of included packets, inserting the synchronization packet into the packet frame, and a packet frame sending unit for sending the packet frame to a transmission path; Prepare.

  Further, the packet receiving means calculates a feature value of each packet in the packet frame, and obtains a synchronization packet including a feature value from a packet frame received from a transmission path, and includes the feature value and the synchronization packet. Means for transmitting each packet downstream in the order of the feature values included in the synchronization packet by comparing the feature values with each other. Also, the following packet transfer apparatus can be used.

  The packet transfer apparatus includes a packet transmission unit that transmits an input packet to a transmission path, and a packet reception unit that receives a packet from the transmission path and transmits the received packet downstream.

  The packet transmission means sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, and for each packet included in the packet frame, the packet and the previous packet A synchronization packet generation / insertion means for generating a synchronization packet storing each packet interval time in the order of packets included in the packet frame, and inserting the synchronization packet into the packet frame; A packet frame sending means for sending the packet frame to the transmission path, wherein the packet receiving means is included in the packet frame; means for acquiring a synchronization packet including a packet interval time from the packet frame received from the transmission path; For each packet, the packet to be sent The packet to be the delivery after delivering preceding packet after the packet interval time corresponding to the packet to be the delivery of Tsu bets and means for sending to the downstream. Details of each means in the two packet transfer apparatuses are as described in the present embodiment.

  In addition, each packet transfer apparatus described in the present embodiment may be used alone or may be used as a circuit component incorporated in the transmission apparatus.

(Effect of embodiment)
According to the packet transfer apparatus according to the present embodiment as described above, the packet input from the user network is sent without being processed, so there is no need for a transmission path in which the maximum packet length that can be transferred is limited. Instantaneous interruption switching is possible.

  In addition, since the packet interval time is included in the synchronization packet, the packet arrival timing can be transferred from the transmission side to the reception side, which makes it possible to suppress the fluctuation of the packet and suppress the influence of the disturbance generated in the network. And stable communication can be performed. Further, since the packet arrival order is included in the synchronization packet and transferred from the transmission side to the reception side, it is possible to correct the order of packets without an order identifier.

  Furthermore, by using the synchronization packet, it becomes possible to transfer additional information necessary for line operation such as absolute time and line ID. Thereby, for example, the absolute delay time can be grasped by comparing the absolute time when the synchronization packet is generated and transmitted on the transmission side and the absolute time when the synchronization packet is received on the reception side.

  In addition, since diversity in the time direction can be achieved, when a plurality of packet transmission paths are provided on the same physical transmission path, packet loss is reduced even when the physical transmission path is switched. It becomes possible to prevent.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

1 is a schematic configuration diagram of a packet transfer system according to an embodiment of the present invention. It is a figure for demonstrating the concept of a synchronous packet production | generation. It is the figure which showed an example of the synchronization packet in detail. 1 is a configuration diagram of a packet transfer device 10. FIG. 3 is a configuration diagram of a synchronization packet generation / insertion unit 23. FIG. 4 is a configuration diagram of a delay difference determination unit 35. FIG. 4 is a configuration diagram of a delay difference adjustment unit 37. FIG. 4 is a configuration diagram of a packet frame selection unit 39. FIG. 4 is a configuration diagram of a packet transmission unit 41. FIG. 6 is a diagram for explaining a specific example of the operation of a packet transmission unit 41. FIG. 4 is a configuration diagram of a packet transmission unit 41. FIG. 3 is a configuration diagram of a packet interval time adjustment unit 50. FIG. It is a figure for demonstrating time diversity. It is a figure for demonstrating time diversity.

Explanation of symbols

1, 3, 10 Packet transfer device 5 Packet transfer network 7, 9 Transmission path 12 Transmission function unit 14 Reception function unit 21 Packet reception unit 23 Synchronization packet generation insertion unit 231 Timing extraction unit 233 Packet feature extraction unit 235 Synchronization information recording unit 237 Synchronization information generation unit 239 Synchronization packet insertion unit 25 Packet copy unit 27A, 27B Packet transmission unit 31A, 31B Packet reception unit 33 Failure detection unit 35 Delay difference determination unit 351 Time recording unit 353 Time difference calculation unit 37 Delay difference adjustment units 371A, 371B Packet storage unit 373 Delay insertion unit 39 Packet frame selection unit 391 Selection instruction unit 393 Selection unit 395 Early arrival determination unit 41 Packet transmission unit 411, 431 Storage operation unit 413, 433 Synchronization packet acquisition unit 415, 435 Feature value acquisition unit 417, 437 packet interval time acquisition unit 419 Packet / feature value storage unit 421 Packet search unit 423, 443 Packet interval time adjustment unit 439 Packet storage memory 441 Feature value / address storage search unit 50 Packet interval time adjustment unit 52 Feature value calculation unit 54 Packet interval time acquisition unit 56 Adjustment unit

Claims (11)

Packet transmission means that duplicates the input packet and sends it to a plurality of transmission lines, receives the packet from the plurality of transmission lines, selects one of the received packets, and downstream A packet transfer device comprising a packet receiving means for sending,
The packet transmission means includes
Synchronization packet generation and insertion means for inserting a predetermined number of packets in a sequentially input packet or a predetermined time of packets into a packet frame sequentially, and inserting a synchronization packet including sequence identification information into each packet frame;
Packet frame sending means for duplicating the packet frame and sending it to a plurality of transmission lines;
The packet receiving means includes
Identify the same packet frame between multiple systems using the synchronization packet order identification information included in each packet frame received from multiple system transmission paths, and determine the delay difference of the same packet frame between multiple systems A delay difference determining means for determining;
A delay adjusting means for adjusting a delay of a packet frame between a plurality of systems using the delay difference obtained by the delay difference determining means;
Packet frame selection means for selecting one system packet frame from a plurality of system packet frames whose delays have been adjusted by the delay adjustment means;
A packet transfer apparatus comprising: packet frame transmission means for transmitting the packet frame selected by the packet frame selection means downstream. The synchronization packet generation / insertion means in the packet transmission means includes an error detection code calculated from a packet included in the packet frame in the synchronization packet,
The packet receiving means further comprises error detection means for detecting an error of the packet frame using an error detection code included in the synchronization packet,
The packet transfer apparatus according to claim 1, wherein the packet frame selection unit selects a packet frame of a system other than the packet frame system in which an error is detected by the error detection unit.   The packet frame selection means comprises early arrival determination means for determining the earliest packet frame among the same packet frames among a plurality of systems, and the packet frame determined to have arrived earliest by the early arrival determination means The packet transfer device according to claim 1, wherein the packet transfer device is sent downstream. The synchronization packet generation / insertion means in the packet transmission means calculates a feature value of each packet included in the packet frame, includes each feature value in the synchronization packet in the order of packets included in the packet frame,
The packet frame sending means in the packet receiving means calculates the feature value of each packet in the received packet frame, and compares the feature value with the feature value included in the synchronization packet, thereby being included in the synchronization packet. 4. The packet transfer apparatus according to claim 1, further comprising means for sending each packet downstream in the order of feature values. The synchronous packet generation / insertion means in the packet transmission means calculates, for each packet included in the packet frame, a packet interval time between the packet and the previous packet, and the packet included in the packet frame Including each packet interval time in the synchronization packet in order;
The packet frame sending means in the packet receiving means sends, for each packet included in the received packet frame, a packet interval corresponding to the packet to be sent after sending the packet immediately before the packet to be sent. 5. The packet transfer apparatus according to claim 1, further comprising means for transmitting the packet to be transmitted downstream after time.   6. The packet transfer according to claim 1, wherein the packet frame sending means in the packet sending means comprises means for adding a delay to a packet frame of one of the plurality of systems. apparatus. A packet transfer apparatus comprising: packet transmitting means for sending an input packet to a transmission line; and packet receiving means for receiving a packet from the transmission line and sending the received packet downstream,
The packet transmission means includes
A packet corresponding to a predetermined number or a predetermined time in sequentially input packets is sequentially set as a packet frame, a feature value of each packet included in the packet frame is calculated, and the order of the packets included in the packet frame is calculated. A synchronization packet generating and inserting means for generating a synchronization packet storing each feature value and inserting the synchronization packet into the packet frame;
Packet frame sending means for sending the packet frame to a transmission path,
The packet receiving means includes
Means for acquiring a synchronization packet including a feature value from a packet frame received from a transmission path;
By calculating the feature value of each packet in the packet frame and comparing the feature value with the feature value included in the synchronization packet, the packets are sent downstream in the order of the feature value included in the synchronization packet. And a packet transfer apparatus. A packet transfer apparatus comprising: packet transmitting means for sending an input packet to a transmission line; and packet receiving means for receiving a packet from the transmission line and sending the received packet downstream,
The packet transmission means includes
A packet for a predetermined number or a predetermined time in a sequentially input packet is set as a sequential packet frame, and for each packet included in the packet frame, a packet interval time between that packet and the previous packet A synchronization packet generating and inserting means for generating a synchronization packet storing each packet interval time in the order of packets included in the packet frame, and inserting the synchronization packet into the packet frame;
Packet frame sending means for sending the packet frame to a transmission path,
The packet receiving means includes
Means for acquiring a synchronization packet including a packet interval time from a packet frame received from a transmission path;
For each packet included in the packet frame, a packet immediately before the packet to be transmitted is transmitted, and then the packet to be transmitted is transmitted downstream after a packet interval time corresponding to the packet to be transmitted. A packet transfer apparatus comprising: A transmission side packet transfer apparatus that duplicates an input packet and sends it to a plurality of transmission paths, receives a packet from the plurality of transmission paths, and selects one of the received packets. A packet transfer method in a packet transfer system comprising a receiving side packet transfer device for sending downstream,
Synchronous packet generation in which the transmission side packet transfer means sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, and inserts a synchronization packet including sequence identification information in each packet frame An insertion step;
A packet frame sending step in which the sending packet transfer means duplicates the packet frame and sends it to the transmission lines of the plurality of systems;
The receiving side packet transfer apparatus identifies the same packet frame among the plurality of systems using the order identification information of the synchronization packet included in each packet frame received from the transmission paths of the plurality of systems, A delay difference determination step for determining a delay difference of the same packet frame between the systems of
A delay adjusting step in which the receiving side packet transfer apparatus adjusts a delay of a packet frame between the plurality of systems using the delay difference obtained in the delay difference determining step;
A packet frame selecting step in which the receiving side packet transfer apparatus selects one system packet frame from the plurality of system packet frames whose delay is adjusted by the delay adjustment step;
A packet frame sending step in which the receiving side packet transfer device sends the packet frame selected in the packet frame selection step downstream;
A packet transfer method comprising: A packet transfer method in a packet transfer system, comprising: a transmission side packet transfer device for sending an input packet to a transmission line; and a reception side packet transfer device for receiving a packet from the transmission line and sending the received packet downstream. There,
The transmission side packet transfer apparatus sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, calculates a feature value of each packet included in the packet frame, and Generating a synchronization packet storing each feature value in the order of packets included in the frame, and inserting the synchronization packet into the packet frame;
A packet frame sending step in which the transmitting packet transfer device sends the packet frame to a transmission path;
The receiving-side packet transfer device obtaining the synchronization packet including the feature value from a packet frame received from the transmission path;
The receiving-side packet transfer apparatus calculates the feature value of each packet in the packet frame, and compares the feature value with the feature value included in the synchronization packet, thereby ordering the feature value included in the synchronization packet. And sending each packet downstream with
A packet transfer method comprising: A packet transfer method in a packet transfer system, comprising: a transmission side packet transfer device for sending an input packet to a transmission line; and a reception side packet transfer device for receiving a packet from the transmission line and sending the received packet downstream. There,
The transmission side packet transfer apparatus sequentially sets a predetermined number of packets or packets for a predetermined time in sequentially input packets as packet frames, and for each packet included in the packet frame, the packet and the previous packet Synchronous packet generation and insertion step of calculating a packet interval time between packets, generating a synchronization packet storing each packet interval time in the order of packets included in the packet frame, and inserting the synchronization packet into the packet frame When,
A packet frame sending step in which the transmitting packet transfer device sends the packet frame to a transmission path;
The receiving-side packet transfer device obtaining the synchronization packet including the packet interval time from a packet frame received from the transmission path;
For each packet included in the packet frame, the receiving side packet transfer apparatus transmits the packet immediately before the packet to be transmitted and then transmits the packet after the packet interval time corresponding to the packet to be transmitted. Sending a packet to be sent downstream;
A packet transfer method comprising:

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