JP3903840B2 - Packet forwarding system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packet transfer system, and more particularly, to a packet transfer system in which, for example, when a packet is switched by switch means such as an edge router, the amount of packet outflow is limited by a contract.
[0002]
[Prior art]
An IP (Internet Protocol) network has become a base for providing services for all communication applications such as telephone and video streaming as well as conventional data communication. Further, with an increase in services that use IP networks, there are cases where transfer of packets that exceed the capacity of the transmission path as a total amount is required. In preparation for such a case, it is considered to preferentially transfer a packet within a traffic volume secured in advance according to the characteristics and service level of a communication application, that is, QoS (Quality of Service).
[0003]
An example of a technique for providing a service for preferentially transferring packets in this way is Diffserv (Differentiated service). Diffserv is defined by "RFC (Request For Comment) 2475" of the Internet Engineering Task Force. In general, when using Diffserve, a contract for service contents is made in advance between a provider providing this service and a user using the service. Next, taking a differential serve as an example, a packet transfer system for transferring packets preferentially will be described.
[0004]
FIG. 12 is a simplified representation of a network in which Diffserve is applied as a packet transfer system. The network 11 includes a core router 12 that transfers packets, and first and second edge routers 13 that transfer packets input to the network 11 to the core router 12.₁, 13₂Is arranged. These first and second edge routers 13₁, 13₂Each includes a packet identification unit 14 that identifies a QoS class of the input packet (Classifier).₁, 14₂And a policer 15 for determining whether or not the traffic volume is within the contracted volume.₁, 15₂And a marker 16 for changing the packet identification value according to the discrimination result of the corresponding policer.₁, 16₂Is provided. Here, the contract amount indicates the traffic amount predetermined in the contract.
[0005]
An operator of this network 11 and a user who wishes to use this network 11 make a service contract (SLA: Service Level Agreement) in advance. This service contract includes the QoS class that the user contracts and the traffic amount that is the amount of packets per unit time transmitted to the network 11. The operator of the network 11 stipulates that for each contracted QoS class, the service quality of transfer including delay, jitter, packet loss rate, etc. is provided. Further, the service provider of the network 11 provides the quality of service as long as the user sends a packet of the traffic amount up to the contract amount to the network 11.
[0006]
Next, a description will be given of operations related to a packet transmitted from a user who has a service contract. After the user makes a service contract with the operator of the network 11, the user sends the packet to the network 11 from a packet sending device (not shown). The packet sent to the network 11 is sent to the first or second edge router 13.₁, 13₂To be input. Here, the first edge router 13₁The packet sent to is described. First, the packet identification unit 14₁Thus, a DSCP (Diffserv Code Point) value, which is an identification value for identifying the contracted QoS class, is added to the packet header. This packet is then sent to policer 15₁And the traffic volume is measured to determine whether or not the traffic volume is within the contract volume as policing. If the traffic volume exceeds the contract volume, the marker 16₁In addition, a value indicating a policing violation is added to the DSCP value added to the packet header of the packet in excess of. A packet to which a value indicating a policing violation is not added becomes a policing success. A packet to which a value indicating a policing violation is added is preferentially discarded when congestion occurs in the network 11. In this way, the core router 12 is the first edge router 13.₁The packet transfer control is performed in accordance with the priority according to the QoS class indicated by the DSCP value assigned in.
[0007]
FIG. 13 shows an example of the traffic volume input to and output from the conventional router. The switch 21 that distributes packets has first and second input ports 22 on the input side.₁, 22₂However, an output port 23 is arranged on the output side. The switch 21 provided in the router has each input port 22₁, 22₂In addition, it is assumed that scheduling is performed in a round-robin manner in which opportunities for switch connection are equally provided to the output ports 23. The first input port 22₁It is assumed that the first user connected to the terminal has a service contract with a contract amount of 1.8 Gbps while the maximum traffic amount is 2.4 Gbps (Giga byte per second).₂It is assumed that the second user connected to the network has a service contract with a contract amount of 0.6 Gbps, while the maximum traffic amount is 2.4 Gbps. Further, it is assumed that the maximum traffic volume that can be output from the output port 23 is 2.4 Gbps.
[0008]
Here, from the first user to the first input port 22₁Packets with a traffic volume 24 of 1.8 Gbps are continuously input from the second user to the second input port 22.₂Suppose that packets with a traffic volume 25 of 1.2 Gbps are continuously input. In this case, a packet having a total amount of 3.0 Gbps is input toward the output port 23. Of the packets input from the second user, 0.6 Gbps within the contracted amount is a packet that passes the policing, and 0.6 Gbps shown as the remaining traffic amount 26 is a packet that violates the policing.
[0009]
However, the switch 21 is a round robin method and includes the first and second input ports 22.₁, 22₂Are assigned to the output ports 23, the respective input ports 22₁, 22₂Thus, a packet of 1.2 Gbps is output to the output port 23. As a result, among the packets input from the first user, the 0.6 Gbps policing pass packet indicated as the traffic volume 27 is blocked by the 0.6 Gbps policing violation packet input from the second user. The As a result, there arises a problem that it becomes impossible to guarantee the transfer of the packet with the contract amount defined in the service contract for the first user.
[0010]
In order to solve such a problem, a technique for adjusting the scheduling of the switch is required so that a packet that passes the policing is preferentially connected to the policing violation packet. For this purpose, there is a technique described in Japanese Patent Laid-Open No. 2000-324168 or Japanese Patent Laid-Open No. 2001-298477.
[0011]
FIG. 14 is for explaining the conventional core router disclosed in these publications. The core router 31 includes first to Pth input buffers 32 respectively corresponding to packets input from first to Pth (not shown) input ports (P is an integer of 2 or more).₁~ 32_PAnd first to Qth output ports 33 (Q is an integer of 2 or more).₁~ 33_QIs provided. Also, the first to Pth input buffers 32₁~ 32_PAnd first to Qth output ports 33₁~ 33_QAre connected to each other, and a scheduler 35 for adjusting the connection relationship is provided.
[0012]
First to Pth input buffers 32₁~ 32_PHave the same circuit configuration. Therefore, as a representative, the first input buffer 32.₁Will be described.
[0013]
First input buffer 32₁Includes a first output port 33.₁The first output port-destined high priority queue 36 for queuing packets with high output priority among packets sent from_1HAnd a low priority queue 36 for the first output port that queues packets with low output priority._1LIs provided. Thus, the first to Qth output ports 33₁~ 33_QA queue corresponding to each of the priority levels is provided. Further, for these queues, a packet distribution unit 37 that distributes packets input from the first input port, and a packet transmission unit 38 that extracts packets from each queue and sends them to the switch 35 are provided. Thus, the packet input to the core router 31 is sent from the first to Pth input buffers 32.₁~ 32_PAre queued in queues respectively corresponding to combinations of output ports and priorities.
[0014]
In the technique disclosed in Japanese Patent Laid-Open No. 2000-324168, a request 39 indicating the output priority of a packet stored from each queue that requests switch connection to the scheduler 34.₁~ 39_PWill be notified. The scheduler 34 makes a request 39₁~ 39_PBased on the above, scheduling is performed so as to preferentially connect a switch with a high priority queue.
[0015]
In the technique disclosed in Japanese Patent Laid-Open No. 2001-298477, the first to Pth input buffers 32 are used.₁~ 32_PWhen a certain number of packets addressed to the same output port are accumulated for each request 39, a request 39 for requesting switch connection₁~ 39_PIs notified to the scheduler 34. The scheduler 34 performs scheduling so that output ports do not overlap, and grant 40 indicating output permission.₁~ 40_PIs notified to the corresponding input buffer. First to Pth input buffers 32₁~ 32_PThis grant 40₁~ 40_PAccordingly, packets are preferentially read from the corresponding high priority queue for the output port. A policing pass packet can be preferentially transmitted by queuing a policing pass as a priority packet and queuing a policing violation packet as a non-priority packet according to priority.
[0016]
[Problems to be solved by the invention]
[0017]
By the way, the packet that passed the policing and the packet that violated the policing are the packets received from the same user and sent to the predetermined destination, simply distinguished from each other in relation to the contract amount. Therefore, considering a case where a user transfers a series of data constituting one application program as a packet, a part of the data is distributed to a packet that passes policing, and the remaining data is transferred to a packet that violates policing. The situation that it is distributed occurs. In the technique described in Japanese Patent Application Laid-Open No. 2000-324168 or Japanese Patent Application Laid-Open No. 2001-298477, policing packets and policing violation packets are queued in different queues, so that the contract amount Packets can be transferred with priority. For this reason, if these techniques are simply applied, the packet in violation of the policing may be transferred later than the packet that has passed the policing. As a result, a situation occurs in which part of the application program that should be received as a series of data is sent to the destination before the remaining part.
[0018]
When the packet transfer order is changed in this way, data is reproduced after the packet receiving side receives a packet with a policing violation transferred late. Therefore, the received application program does not work well. For data that requires real-time performance, such as telephone and video streaming, if the packet transfer order is changed, the quality of the data to be reproduced will be reduced or meaningless as data.
[0019]
Therefore, an object of the present invention is such that when a plurality of users send packets to the same destination, their own packets are sent to the destination in order in time regardless of the existence of other users' packets. Is to provide a packet transfer system.
[0022]
[Means for Solving the Problems]
  Claim 1In the described invention, (a) the amount of packet inflow per unit time isIndividuallyMultiple specified inflow transmission linesArranged in eachPacket outflow per unit timeEach specified separatelyPacket receiving means for receiving each packet destined for the outflow transmission path, and (b)Arranged corresponding to each of the plurality of inflow transmission lines described above,Received by packet receiving meansCorrespondingOf the packets that have passed through the inflow side transmission path, the outflow amount per unit time is preliminarily determined for each inflow side transmission path.RegulationThe amount that exceeds the amountRegulationIdentifier adding means for selectively adding an identifier to a packet that has flowed in so as to distinguish it from the received packet;Arranged corresponding to each of the plurality of inflow transmission lines described above,Each packet after the identifier is selectively added by the identifier adding means is stored on a first-come-first-served basis,As described abovepluralOutflow transmission linePacket storage means provided for each of them, and (d)Arranged corresponding to each of the plurality of inflow transmission lines described above,Each stored in these packet storage meansFirst positionPacket retrieval means for checking packets and preferentially retrieving packets whose outflow amount per unit time is secured by the identifier per unit time within the range of packet outflow amount per unit time of the outflow side transmission path; (E)Each of the plurality of inflow transmission lines described abovePackets extracted by the packet extraction meansA plurality of the aboveOutflow transmission lineCorresponding toThe packet transfer system is provided with a packet transmission means for transmitting to the packet.
[0023]
  Claims1In the described invention, when receiving packets directed to the same outflow side transmission path common to these from a plurality of inflow side transmission paths,Arranged corresponding to each of the multiple inflow transmission linesThe identifier adding means determines the amount of outflow per unit time in advance for each inbound transmission line.RegulationAn identifier is added to the packet so as to distinguish the amount that has been used from the others.thisEach packet after the identifier is selectively added by the identifier adding means is composed of a plurality of inflow transmission paths.A plurality of outflow side transmission lines arranged corresponding to each of the above-mentionedEach packet is stored in a first-come-first-served basis in the corresponding packet storage means. Then, the packet extracting means checks the packet at the next extraction position stored in each of these packet storing means, and within the range of the packet outflow amount per unit time of the outflow side transmission path, the identifier per unit time is determined by the identifier. A packet for which the outflow amount is secured is preferentially taken out every unit time. Therefore, the packet extracting means preferentially extracts packets from the respective packet storage means within the range of the packet outflow amount per unit time of the outflow side transmission path, as much as there is an arrangement for securing. A packet in which the outflow amount per unit time is secured is preferentially taken out. At this time, if attention is paid to the respective packet storage means, the packet is taken out by the so-called first-in first-out principle. For this reason, inflow packets are taken out in order in time in each inflow side transmission path and sent out to the outflow side transmission path, thereby avoiding the inconvenience of out of order.
[0024]
  Claim2In the described invention, (a) the amount of packet inflow per unit time isIndividuallyMultiple specified inflow transmission linesArranged in eachPacket outflow per unit timeEach specified separatelyPacket receiving means for receiving each packet destined for the outflow transmission path, and (b)Arranged corresponding to each of the plurality of inflow transmission lines described above,Received by packet receiving meansCorrespondingOf the packets that have passed through the inflow side transmission path, the outflow amount per unit time is preliminarily determined for each inflow side transmission path.RegulationThe amount that exceeds the amountRegulationIdentifier adding means for selectively adding an identifier to a packet that has flowed in so as to distinguish it from the received packet;Arranged corresponding to each of the plurality of inflow transmission lines described above,Each packet after the identifier is selectively added by the identifier adding means is stored on a first-come-first-served basis,As described abovepluralOutflow transmission linePacket storage means provided corresponding to each, (d) extraction priority registration means for registering the priority when packets taken out from these packet storage means for each inflow-side transmission path compete for extraction; (E)Arranged corresponding to each of the plurality of inflow transmission lines described above,The packet at the head position stored in the packet storage means is checked, and the packet for which the outflow amount per unit time is secured by the identifier within the range of the packet outflow amount per unit time on the outflow side transmission path A packet extraction means for preferentially extracting packets with a high extraction priority registered in the extraction priority registration means between packets for which the outflow amount per unit time is ensured when each packet is preferentially extracted; )Each of the plurality of inflow transmission lines described aboveThe packet extracted by the packet extracting means ofpluralOutflow transmission lineCorresponding toThe packet transfer system is provided with a packet transmission means for transmitting to the packet.
[0025]
  Claims2In the described invention, when receiving packets directed to the same outflow side transmission path common to these from a plurality of inflow side transmission paths,Arranged corresponding to each of the multiple inflow transmission linesThe identifier adding means determines the amount of outflow per unit time in advance for each inbound transmission line.RegulationAn identifier is added to the packet so as to distinguish the amount that has been used from the others.thisEach packet after the identifier is selectively added by the identifier adding means is composed of a plurality of inflow transmission paths.A plurality of outflow side transmission lines arranged corresponding to each of the above-mentionedEach packet is stored in a first-come-first-served basis in the corresponding packet storage means. By the way, in the present invention, the extraction priority registration means registers the high priority of extraction from the packet storage means of the packet stored via the inflow side transmission path corresponding to each inflow side transmission path. Yes. Then, the packet extracting means checks the packet at the next extraction position stored in each of these packet storing means, and within the range of the packet outflow amount per unit time of the outflow side transmission path, the identifier per unit time is determined by the identifier. A packet for which the outflow amount is secured is preferentially taken out every unit time. However, there may be a competition for extraction among a plurality of packet storage means in relation to the outflow amount per unit time. At this time, a high priority registered in the extraction priority registration means is preferentially extracted.
[0028]
  Claim 3In the described invention,Claim 1 or claim 2In the packet transfer system described above, the identifier adding means includes an outflow amount per unit time that exceeds the amount reserved in advance for each inflow side transmission path among the packets that have passed through each inflow side transmission path received by the packet receiving means. It is characterized in that an identifier is added for each part.
[0029]
  IeClaim 3In the described invention, identifiers are added to packets for the amount of outflow per unit time exceeding the amount reserved in advance for each inflow side transmission path.
[0030]
  Claim 4In the described invention,Claim 1 or claim 2In the packet transfer system described above, the identifier adding means identifies the amount of outflow per unit time that is secured in advance for each inflow side transmission path among the packets that have passed through each inflow side transmission path received by the packet reception means. It is characterized by adding.
[0031]
  IeClaim 4In the described invention, identifiers are added to packets for which the amount of outflow per unit time is secured in advance for each inflow side transmission path.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
[0033]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[0034]
First embodiment
[0035]
FIG. 1 shows an outline of an IP network constituting a packet transfer system in a first embodiment of the present invention. The IP network 101 includes first to third access networks 102 that are networks in a relatively narrow range.₁~ 102_ThreeThese first to third access networks 102₁~ 102_ThreeIs connected to the core network 103. First to third access networks 102₁~ 102_ThreeIndicates a network that connects to terminals in each home using, for example, a CATV (cable television) distribution network. The core network 103 refers to a network created by a telephone company or the like using a high-speed line connecting cities. First to third access networks 102₁~ 102_Three1st to 3rd customer premises equipment (CPE) 104 for transmitting and receiving packets to and from the core network 103, respectively.₁~ 104_ThreeIs provided. In the core network 103, first to third customer premises equipment 104 are provided.₁~ 104_ThreeThe first to third edge routers 105 that directly transmit / receive packets to / from₁~ 105_ThreeAnd the first and second core routers 106 that perform packet transfer processing in the core network 103₁, 106₂Is provided.
[0036]
FIG. 2 shows the structure of the core router arranged in the core network shown in FIG. Here, the first core router 106₁The second core router 106 will be described.₂Since the configuration is the same, the description thereof is omitted. First core router 106₁The first to Nth input ports 111 (N is an integer of 2 or more) connected to the transmission path through which the packet flows.₁~ 111_NAnd the first to Nth preprocessing units 112 that perform preprocessing on the input packet₁~ 112_NAnd the first to Nth input buffers 113₁~ 113_NIs provided. The switch 114, the scheduler 115 that performs scheduling of the switch 114, and the first to Mth output ports 116 (M is an integer of 1 or more) connected to the transmission path on the packet outflow side.₁~ 116_MIs provided. First core router 106₁Is further provided with a control unit 127. The control unit 127 includes a CPU (Central Processing Unit) (not shown). The processing unit 127 also includes a first core router 106 according to a program stored in a storage medium (not shown).₁Control of each part is performed. The control unit 127 is supplied with the clock signal 129 from the clock signal generator 128. First core router 106₁In this way, the first to Nth input buffers 113 are arranged in front of the switch 114.₁~ 113_NIt is configured as an input buffer type switch provided with.
[0037]
First to Nth input buffers 113₁~ 113_NHave the same circuit configuration. Therefore, as a representative, the first input buffer 113 is used.₁Will be described. First input buffer 113₁Includes first to Mth output port-addressed queues 117 provided corresponding to the respective output ports.₁~ 117_MAnd queues 117 for these output ports₁~ 117_MA packet distribution unit 118 that distributes packets to the output port, and an output port-destined queue 117.₁~ 117_MIs provided with a packet sending unit 119 for taking out the packet from the head of the packet and sending it to the switch 114. The first to Mth output port queues 117₁~ 117_M1st to Mth header inspection units 120 corresponding one-to-one₁~ 120_MAnd the first to Mth output port queues 117₁~ 117_MIs provided with a buffer control unit 121 for selecting one of them. First to Mth output port queues 117₁~ 117_MAre the first to Mth output ports 116, respectively.₁~ 116_MThis is a first-in first-out (FIFO) virtual output port queue (Virtual Output Queue: VOQ) for storing packets sent from the network.
[0038]
The packet distribution unit 118 includes a first input buffer 113.₁1st to Mth output port-addressed queues 117 corresponding to the destinations of the packets input to₁~ 117_MIt is supposed to be queued. At this time, if the destination is the same, the queue 117 for the same output port regardless of whether the policing has passed or the policing violation has occurred.₁~ 117_MAre queued in the order of input. In this embodiment, the first to Mth output port queues 117 are also provided.₁~ 117_MWhen the packet distributor 118 queues up to the limit of the storage amount, no more packets are input and discarded.
[0039]
First to Mth header inspection units 120₁~ 120_MAre the corresponding first to Mth output port queues 117 respectively.₁~ 117_MThe header of the packet stored at the beginning of the packet is inspected. First to Mth header inspection units 120₁~ 120_MThe first to Mth test result information 122 is obtained from each test result.₁~ 122_MIs notified to the buffer control unit 121. Inspection result information 122₁~ 122_MIncludes information indicating whether or not the packet is queued, and information indicating whether or not an identifier indicating a policing violation is incorporated in the header of the first packet if the packet is queued. Yes. The buffer control unit 121 requests the scheduler 115 to request connection to the switch 114 and the request 123 indicating the connection priority.₁To be notified. Here, the information on the connection priority indicates information on either a policing pass or a policing violation incorporated in the header of the packet. Also, this request 123₁Grant 124 indicating the output port that permits connection to₁, And the output port-addressed queue 117 corresponding to this₁~ 117_MIs sent to the packet sending unit 119.
[0040]
The scheduler 115 includes first to Nth input buffers 113.₁~ 113_NRequest 123 notified from₁~ 123_NTo receive. The received request is sent to the first to Mth output ports 116.₁~ 116_MSeparately, a grant indicating an output port that permits connection is notified to the input buffer that has notified the request having the highest connection priority. Here, the connection priority is two stages of policing pass and policing violation, and the policing pass is set to a higher priority. Request 123₁~ 123_NWhen a plurality of messages having the highest priority are sent to the same output port, one is selected by the round robin method. The output port is selected at a timing according to a time slot based on the clock signal 129. First to Nth input buffers 113₁~ 113_NAnd the first to Mth output ports 116₁~ 116_MIs determined, the switch 114 is notified of connection setting information 126 indicating this connection relationship. The switch 114 performs the first to Nth input buffers 113 according to the received connection setting information 126.₁~ 113_NAnd the first to Mth output ports 116₁~ 116_MSet to connect.
[0041]
FIG. 3 shows the configuration of the first preprocessing unit shown in FIG. First to Nth pre-processing units 112₁~ 112_NHave the same circuit configuration. Therefore, as a representative, the first preprocessing unit 112.₁Will be described. First preprocessing unit 112₁Are provided with a packet identification unit 131 for giving QoS class identification information to a packet, and a policer 132 for determining whether or not the inflow amount of a packet as a traffic amount is within a contract amount. In addition, a marker 133 that incorporates the determination result of the policer 132 into the packet, and an output port 116 that transmits the packet.₁~ 116_MAn output port discrimination unit 134 and a packet division unit 135 that divides a packet into a predetermined length or less. The policer 132 includes a storage medium (not shown) for storing the contract amount.
[0042]
Input port 111₁First, the packet identifier 131 determines a corresponding QoS class, and a DSCP value for identifying the determined QoS class is added to the header of the packet. Next, the policer 132 checks whether or not the inflow amount of packets received as policing is within the contract amount. For example, the packets are stored in the first-in first-out buffer that discharges all the packets stored per unit time in the order of input, and the check is made by distinguishing the number of packets from the beginning up to the number corresponding to the contract amount and the number exceeding that I do. If the amount exceeds the contract amount, a marker 133 is attached to the exceeding amount of packets, and an identifier indicating a policing violation is added to the DSCP value, resulting in a policing violation packet. A packet in which an identifier indicating a policing violation is not attached to the DSCP value by the marker 133 is a policing pass packet. The packet reflecting the policing result is output from the first core router 106 by the output port discrimination unit 134.₁Output port 116 of₁~ 116_MFrom which the packet is transmitted, and information indicating this is added to the packet header. Finally, the packet dividing unit 135 divides the packet so as to be a predetermined length or less, and the first preprocessing unit 112 is divided.₁To send from. When this division is performed, the information incorporated in the packet header is copied and incorporated in each divided packet.
[0043]
FIG. 4 shows the configuration of the buffer control unit provided in the first input buffer shown in FIG. The buffer control unit 121 includes the inspection result information 122.₁~ 122_MAnd the request 123 based on the received inspection result information.₁A request creating unit 142 for creating a request and a created request 123₁Is provided to the scheduler 115. The buffer control unit 121 also receives a grant 124 sent from the scheduler 115.₁Grant receiver 144 and grant 124₁Queue selection unit 145 for selecting a queue destined for an output port that transmits a packet based on the packet, and selection queue information notifying unit 146 for notifying packet sending unit 119 of selection queue information 125 indicating the queue destined for the output port. It has been.
[0044]
The request creation unit 142 displays the inspection result information 122.₁~ 122_MA request 123 incorporating a desired connection destination output port indicating an output port to which a packet queued in the queue and a connection priority indicating the priority of the packet are incorporated.₁Create If there are a plurality of queues for output ports where packets are queued, information corresponding to the number is incorporated into one request 123.₁May be created. In this case, the connection priority is indicated for each desired connection destination output port. Further, the queue selection unit 145 has the grant reception unit 144 that grant 124.₁, The first to Mth output port queues 117 are received.₁~ 117_MThe one corresponding to this is selected. Suppose this is the first output port queue 117.₁Then, the packet sending unit 119 sends the first output port-addressed queue 117.₁The packet is extracted from the head of the packet and sent to the switch 114. The scheduler 115 notifies the connection setting information 126 so as to set the connection between the corresponding input buffer and the output port in time for the packet sending unit 119 to send the packet to the switch 114. Therefore, the packet 147 sent from the packet sending unit 119 to the switch 114.₁Is sent from the corresponding output port via the switch 114.
[0045]
Next, the core router 106₁The manner in which a packet is input and transmitted is described. First input port 111 shown in FIG.₁Includes the first edge router 105 shown in FIG.₁Via the first access network 102₁Packets are input from. Also, the second input port 111, not shown in FIG.₂Includes the second edge router 105 shown in FIG.₂Via the second access network 102₂Packets are input from. The operator of the core network 103 is the first access network 102₁And a service contract with a contract amount of 1.8 Gbps is assumed. The second access network 102₂And a service contract with a contract amount of 0.6 Gbps is assumed. First output port 116₁It is assumed that a maximum of 2.4 Gbps packets can be transmitted from. Here, the first output port 116₁Packets transmitted from the first and second access networks 102₁, 102₂It is assumed that there are only packets input from each operator. Thereby, the first and second access networks 102₁, 102₂As long as packets are input from each carrier with a total traffic amount of 2.4 Gbps, all the input packets are output to the first output port 116 regardless of the contract amount.₁Is sent from.
[0046]
FIG. 5 shows an example of a state in which a packet to be sent to the first output port has a contention for sending in the core router shown in FIG. First input port 111₁The first access network 102₁The packet of 1.8 Gbps indicated by the traffic amount 151 from is continuously input. Since this traffic amount 151 is within the contracted amount, these packets are all policing packets. Second input port 111₂Has a second access network 102₂The packet of 1.2 Gbps indicated by the traffic amount 152 from is continuously input. Since the traffic amount 152 exceeds the contract amount, the excess traffic amount of 0.6 Gbps packet is a policing violation packet and is given an identifier. A packet with a traffic amount of 0.6 Gbps within the contract amount is a packet that has passed policing.
[0047]
Core router 106₁In this case, a packet that passes policing is sent to the switch in preference to a packet that violates policing. Thus, the first input port 111₁Since all the packets input from are packets that have passed the policing, these are the first output ports 116.₁Will be sent preferentially. Also, the second input port 111₂Packets received from the first output port 116 by 0.6 Gbps, including policing pass and policing violation.₁Is sent from. Also, the second input port 111₂Among packets input from, a packet with a traffic amount of 0.6 Gbps indicated by an arrow 153 is discarded. Since packets within the traffic amount 152 queue policing pass packets and policing violation packets in the same queue in the order of input, the discarded packets may include policing pass packets. However, at least a packet with a traffic volume of 152 is transmitted to the second input port 111.₂Without changing the input order from the first output port 116₁Can be sent from. In this example, the first and second access networks 102₁, 102₂As described above, a case where a packet with a fixed traffic amount is input is described. However, for example, the first access network 102₁When the traffic volume of the packet input from fluctuates, the output port 116₁The amount of packets indicated by the traffic amount 153 can be transmitted by the margin of the traffic amount on the side.
[0048]
Thus, the core router 106₁Then, when a policing pass packet is preferentially transferred when it conflicts with a policing violation packet, a contract amount packet composed of only the policing pass packet can be transferred preferentially. Thereby, the policing violation packet of the other input port does not block the policing pass packet of its own input port, and the unfairness of the output opportunity between the input ports can be reduced. When the output ports are the same, the policing pass packet and the policing violation packet are queued in the same queue in the order of input. As a result, the order of packets transmitted from the same output port among the packets input from the same input port is not changed. Even when packet discarding occurs, packets that cannot be queued in the queue are discarded, so that the sequence is not changed even if a series of packets are lost.
[0049]
Second embodiment
[0050]
FIG. 6 shows a part of the core router constituting the packet transfer system in the second embodiment of the present invention. In this figure, the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. Also in this embodiment, FIG. 1 of the first embodiment is appropriately used. First core router 106A₁Includes first to Nth input ports 111 to which packets are input.₁~ 111_NAnd first to Nth pre-processing units 201 for adding identifiers indicating connection priorities to the input packets.₁~ 201_NAnd first to Nth input buffers 202 for temporarily storing input packets.₁~ 202_NIs provided. The switch 114 selectively connects the input side and the output side, and the first to Mth output ports 116 serving as packet destinations.₁~ 116_MAnd the first to Nth input buffers 202₁~ 202_NIs provided with a scheduler 203 that schedules connection of the switch 114 according to the connection priority of the packet stored in. Further, the first to Nth input buffers 202₁~ 202_NAre the first to Nth requests 204 incorporating information indicating the connection priority.₁~ 204_NIs notified to the scheduler 203. In the second embodiment, description will be made assuming that 103 operators of the core network support a plurality of QoS classes of class 1 to class X (X is an integer of 2 or more) like Diffserve.
[0051]
FIG. 7 shows the configuration of the first preprocessing unit shown in FIG. In this figure, the same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. First preprocessing unit 201₁Includes a first input port 111₁A user class identification unit 211 for adding a DSCP value identifying a user who is a transmission source of a packet input from the user and a QoS class contracted with the user to the packet, and a first policing of the traffic amount corresponding to each user -Fourth policer 212₁~ 212_FourAnd the first to fourth markers 213 that selectively incorporate policing violation identifiers in the packet header corresponding to these.₁~ 213_FourIs provided. First to fourth policers 212₁~ 212_FourAnd the first to fourth markers 213₁~ 213_FourAre provided corresponding to the first to fourth users, respectively. In addition, the first preprocessing unit 201₁Are provided with an output port discriminating unit 134 for discriminating an output port as a packet transmission destination and a packet dividing unit 135 for dividing the packet into a predetermined length or less. First input port 111₁Are sent from the first to fourth users who have signed a service contract with the provider of the core network 103 in advance. First to fourth policers 212₁~ 212_FourAnd the first to fourth markers 213₁~ 213_FourPolices whether or not the traffic volume from the first to fourth users is within the contract amount, and an identifier indicating a policing violation is given to the packet exceeding the contract amount.
[0052]
FIG. 8 shows the configuration of the first input buffer shown in FIG. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. First input buffer 113₁Includes 11th to XMth queues 221 storing packets prepared for each combination of output port and supported QoS class.₁₁~ 221_XMA packet distribution unit 118 that distributes packets to these queues, and a packet transmission unit 119 that takes out the packets stored at the heads of these queues and sends them to the switch 114. Here, the first place value of the subscript number assigned to the queue 221 represents the corresponding output port, and the ten place value represents the corresponding QoS class. Also, the 11th to XMth queues 221₁₁~ 221_XM11 to XM header inspection units 222 that inspect the head packet in a one-to-one correspondence with each other.₁₁~ 222_XMAnd the 11th to XMth queues 221₁₁~ 221_XMIs provided with a buffer control unit 223 for selecting one of them.
[0053]
The packet distribution unit 118 receives packets input from the first to fourth users from the first preprocessing unit 201.₁11 to XM queues 221 prepared for each output port and for each QoS class based on the processing result of₁₁~ 221_XMIt is supposed to be queued. 11th to Xth header inspection units 222₁₁~ 222_XMAre the corresponding first to XM queues 221.₁₁~ 221_XMIt checks for the presence of packets that are queued to. If the packet is queued, it is checked whether an identifier indicating policing violation is added to the head packet. Header inspection unit 222₁₁~ 222_XMThe inspection result is referred to as inspection result information 122.₁₁~ 122_XMIs notified to the buffer control unit 223. The buffer control unit 223 receives the inspection result information 122.₁₁~ 122_XMA request 204 which is a connection request to the switch 114 created based on₁Is notified to the scheduler 203. On the other hand, the output port 116 that is permitted to connect.₁~ 116_NGrant 124 indicating either₁Is received, the selection queue information 125 is notified to the packet transmission unit 119.
[0054]
FIG. 9 shows the configuration of the buffer control unit shown in FIG. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The buffer control unit 223 includes the inspection result information 122.₁₁~ 122_XMThe test result information receiving unit 141 that receives the request 204 and the request 204 based on this₁Request creation unit 231 for creating request 204 and request 204₁Is notified to the scheduler 203. Also, grant 124 from scheduler 203₁And the 11th to XM queues 221 based on this.₁₁~ 221_XMA queue selection unit 232 for selecting a queue from which a packet to be transmitted to the switch 114 is extracted, and a selection queue information notification unit 146 for notifying the packet transmission unit 119 of selection queue information 125 indicating the selected queue. Further, a priority order table 233 is stored which stores the priority order of connection priorities according to the combination of the QoS class and policing pass or policing violation. The request creation unit 231 and the queue selection unit 232 refer to the priority order stored in the priority order table 233 when determining whether the connection priority is high or low.
[0055]
Unlike the first embodiment, the request creation unit 231 considers not only the policing pass or policing violation but also the priority order between QoS classes.₁Is supposed to create. For example, output port 116₁The policing packets addressed to the 11th and 21st queues 221₁₁221_{twenty one}Are stored, and the combination of the second QoS class and the policing pass is set higher in priority than the combination of the first QoS class and the policing pass. In this case, since the combination of the second QoS class and the policing pass has a higher priority, the output port 116 incorporating the connection priority registered in the priority order table 233 accordingly.₁Request 204 to request connection to₁Create The queue selection unit 232 receives the grant 124 received by the grant reception unit 144.₁In accordance with the first to XM queues 221₁₁~ 221_XMThe queue from which the packet to be sent to the switch 114 is taken out is selected. As an example, Grant 124₁Output port 116₁If the connection permission to the output port 116 is indicated, the output port 116₁11th to 1M queues 221 addressed to₁₁~ 221_1MThe queue storing the packet having the highest connection priority among the packets stored at the head position of is selected. The queue selection unit 232 acquires the latest inspection result information from the inspection result information receiving unit 141 for this selection. Then, the queue selection unit 232, for example, the first M queue 221_1MIs selected, the first M queue 221 is selected._1MThe packet is extracted from the head of the packet and sent to the switch 114. The scheduler 203 notifies the corresponding input buffer 202 by notifying the connection setting information 126 in time for the timing at which the packet sending unit 119 sends the packet to the switch 114.₁And output port 116₁It is supposed to set the connection. Therefore, the packet 147 sent from the packet sending unit 119 to the switch 114.₁Corresponds to the corresponding output port 116 via the switch 114.₁To be sent from.
[0056]
FIG. 10 shows the configuration of the scheduler shown in FIG. The scheduler 203 includes first to Nth input buffers 202.₁~ 202_NRequest 204 sent from₁~ 204_NAnd a first to Xth request storage unit 242 for temporarily storing a request for each of the first to Xth QoS classes.₁~ 242_XAnd a class-specific request distribution unit 243 that distributes the received requests to them. In addition, a priority order table 244 storing a priority order of connection priorities according to a combination of a QoS class and policing pass or policing violation, and first to Xth request storage units 242₁~ 242_XEach input buffer 202 based on the priority order of the requests and connection priorities stored in₁~ 202_NOutput port 116 connected to₁~ 116_MAn output port selection unit 245 is provided. Further, each input buffer 202 is selected based on the selection of the output port selection unit 245.₁~ 202_NOutput port 116 which permits connection according to₁~ 116_MAs one of the grants 124₁~ 124_NThe grant creation unit 246 for creating the grant and the grant 124 created by the grant creation unit 246₁~ 124_NFor each input buffer 202₁~ 202_NA connection information creation unit 248 that creates connection information indicating connection settings of the switch 114 based on selection by the output port selection unit 245, and connection information 126 created by the connection information creation unit 248. Is provided with a connection information notification unit 249.
[0057]
The output port selection unit 245 refers to the connection priority stored in the priority order table 244, and the first to Xth request storage units 242 corresponding to the QoS class having a high connection priority.₁~ 242_XOutput port 116 in order from the request stored in₁~ 116_MIs supposed to be selected. The output port selection unit 245 includes the input buffer 202₁~ 202_NList showing output and output port 116₁~ 116_MEach of the input buffers 202 that are not selected in these lists.₁~ 202_NAnd output port 116₁~ 116_MThe connection relationship is determined by selecting one by one. At this time, the input buffer 202₁~ 202_NAnd output port 116₁~ 116_MThe selected one of the output ports 116 is selected for one input buffer.₁~ 116_MCan be prevented from being selected at the same time. The grant creation unit 246 receives the input buffer 202.₁~ 202_NOf the corresponding output ports 116₁~ 116_MGrant 124 for notifying permission of connection to those selected₁~ 124_NIs supposed to create.
[0058]
Of the connection priorities stored in the priority order tables 233 and 244, the packet with the policing violation is given the lowest priority regardless of the priority of the QoS class. Since the connection priority is determined by the priority order stored in the priority order tables 233 and 244, an arbitrary priority order can be set by changing this setting. Next, a case where a plurality of QoS class packets cause contention will be described.
[0059]
FIG. 11 shows an example of a state in which a packet to be transmitted to the first output port has a contention in the core router described in the second embodiment. Here, the first input port 111₁And the second input port 111₂Of the packets input to the first output port 116₁What is sent out to will be described. First input port 111₁Are continuously inputted with a packet for 0.4 Gbps indicated by the traffic amount 251 of the first QoS class and a packet for 1.0 Gbps indicated by the traffic amount 252 of the second QoS class. Second input port 111₂The packet for 0.6 Gbps indicated by the traffic amount 253 of the second QoS class and the packet for 0.8 Gbps indicated by the traffic amount 254 of the third QoS class are continuously input. First output port 116₁Can transmit packets up to a maximum of 2.4 Gbps. The connection priority between QoS classes is highest in the first QoS class, and is in the order of the second and third QoS classes. In addition, the connection priority of the packet with the policing violation identifier indicating the packet exceeding the contract amount determined for each of the first to fourth users is the lowest connection priority regardless of the QoS class. Is set to
[0060]
First input port 111₁The second QoS class packet input from is composed of a policing pass packet for 0.6 Gbps and a policing violation packet for 0.4 Gbps. First input port 111₁Packets of the first QoS class input from the second input port 111₂The packets of the second QoS class and the third QoS class that are input from are configured only by policing pass packets.
[0061]
Core router 106A₁In this case, a packet having a high connection priority is sent to the switch 114 with priority. However, the first input port 111₁Packets of the second QoS class inputted from the 21st queue 221_{twenty one}Depending on the connection priority of the packet queued at the head of the packet, the priority may be reversed. Here, to simplify the problem, the first input port 111₁Description will be made assuming two states of the second QoS class packet input from No. 1 when the policing pass packet is biased toward the head of the queue and when it is biased toward the rear.
[0062]
First, the first input port 111₁Among the packets of the second QoS class input from, the policing pass packet is the 21st queue 221._{twenty one}The case where it is biased to the top of will be described. In this case, the first input port 111 having the highest connection priority.₁The first QoS class packet input from is first transmitted. Then, the first and second input ports 111 having the next highest connection priority.₁, 111₂Packets that pass the second QoS class policing that are input from the terminal are equally sent by 0.6 Gbps in a round robin manner. After this, the first input port 111₁And a second QoS port policing violation packet input from the second input port 111₂There remains a packet that has passed the policing of the third QoS class input from. Since the policing violation packet has the lowest connection priority, a packet for 0.8 Gbps of the third QoS class is output first. As a result, a packet corresponding to a total traffic amount of 2.4 Gbps is output, so the first input port 111 indicated by the traffic 255 is displayed.₁The remaining 0.4 Gbps packets of the second QoS class input from are discarded.
[0063]
Next, the first input port 111₁A case will be described in which packets that pass the policing among the packets of the second QoS class input from the above are biased toward the back of the queue. In this case, the first input port 111₁Queue 221 for storing packets of the second QoS class inputted from_{twenty one}Has the lowest connection priority because a policing violation packet is stored at its head. Therefore, the first input port 111₁First, packets other than the second QoS class input from are sequentially transmitted in accordance with the high connection priority. Finally, the first input port 111₁Of the second QoS class packets input from, the output is 0.6 Gbps, and the remaining 0.4 Gbps packets are discarded.
[0064]
Thus, the third QoS class policing pass packet having a lower connection priority than the second QoS class policing pass traffic is sent without being blocked by the second QoS class policing violation packet. Can do. Therefore, the core router 106A of the second embodiment₁Thus, even when a plurality of QoS classes having different connection priorities are supported, the same effect as in the first embodiment can be realized.
[0065]
In the first and second embodiments described above, the core router 106₁Or core router 106A₁Explained that it has a control unit 127, which controls according to the program. However, each unit may be configured by hardware synchronized with the clock signal 129. The first to Mth output port queues 117₁~ 117_MAnd the 11th to XMth queues 221₁₁~ 221_XMMay be provided as physically independent storage media, or may be provided in a form of virtually dividing an appropriate number of storage media.
[0066]
In the first and second embodiments, an identifier for policing violation is selectively incorporated in a packet input from the relationship between traffic volume and contract volume. However, the traffic volume is not particularly defined in the service contract, and a policing violation identifier may always be incorporated in a packet from a specific user. If only the policing violation identifier is incorporated, the packet input from the user will be transferred using the bandwidth after transferring other packets with high transfer priority, regardless of the traffic volume. When congestion occurs, the amount of packets that can be transferred is often limited. For example, instead of providing such a restriction, a service contract that is relatively cheaper than a service contract that defines a contract amount may be concluded with a user who uses the conventional data communication whose transfer speed is not so high.
[0067]
Furthermore, in the second embodiment, for example, if the traffic volume is secured by the same amount as the maximum traffic volume per unit time on the outflow side and the user is contracted to set the highest connection priority, the communication at the time of disaster etc. is maximized. It is also possible to prepare a service contract suitable for securing priority.
[0068]
Potential variations of the invention
[0069]
In the first or second embodiment, the packet input based on the contract amount is divided into either a policing pass or a policing violation. In order to identify this, in the first and second embodiments, an identifier indicating policing violation is incorporated into the packet, but an identifier indicating policing success may be incorporated. Further, the priority may be further divided in this policing pass or policing violation. For example, two traffic volumes, a limit traffic volume (Peak Rate) and an average traffic volume (Committed Rate), are defined in a service contract. A portion that is less than the average traffic amount is a policing pass packet, a portion that is greater than or equal to the average traffic amount and less than the limit traffic amount is a first policing violation packet, and a portion that is more than the limit traffic is a second policing violation packet. Scheduling is performed preferentially in descending order of connection priority as a policing pass packet, a first policing violation packet, and a second policing violation packet in descending order. This makes it possible, for example, to preferentially output packets input from other input ports with a traffic amount slightly exceeding the average value, rather than packets input from a certain input port with a temporarily maximized traffic amount. Services can be provided.
[0070]
Further, in the first embodiment, the first preprocessing unit 112 is used.₁The class identification unit 131, the policer 132, and the marker 133 are provided. However, these are the first input ports 111₁First edge router 105 that inputs a packet to₁May be provided. Also, the first preprocessing unit 201 of the second embodiment.₁User class identification unit 211 and first to fourth policers 212 provided in₁~ 212_FourAnd the first to fourth markers 213₁~ 213_FourThe first edge router 105₁May be provided. In this way, the process of adding the identification value indicating the policing violation is performed across the network by the first edge router 105.₁The first core router 106₁Can reduce the load of packet transfer processing.
[0071]
Further, in the second embodiment, the priority order tables 233 and 244 are provided in the buffer control unit 223 and the scheduler 203, respectively. However, the combination of the QoS class and the policing violation or policing pass is associated with a linear priority, which is referred to as the request 204.₁It may be incorporated as the connection priority of. Thereby, the scheduler 203 makes a request 204.₁~ 204_NPriority scheduling can be performed by simply comparing the connection priorities built in the network. As described above, the scheduler 203 may not include the priority order table 244. At this time, in the case of setting the policing violation packet to the lowest priority order regardless of the QoS class, it is possible to realize preferential scheduling by providing the order of (X + 1) stages as the connection priority. In addition, when setting the priority order of policing violation and policing pass packets for each QoS class, it is possible to realize preferential scheduling by providing (2 × X) stages of connection priorities. .
[0072]
【The invention's effect】
  Claim 1 as described aboveOr claim 2According to the described invention, each inflow side transmission pathCorresponding to each of multiple outflow side transmission linesPlace packet storage meansEtPackets are stored on the first-come-first-served basis, and the packets stored in the packet storage means from each inflow-side transmission path are surely allocated to the inflow-side transmission path by allocating the packets stored in advance. It is sent out to the inflow side transmission path in the storing order, and the order does not go out of order. In addition, by setting the superiority or inferiority when the packet is taken out from each packet storage means, it becomes possible to transmit the packet according to the priority.
[0073]
  MoreClaim 2According to the described invention, since not only the priority of each packet but also the priority between the packet storage means is determined, when a conflict occurs when a packet is extracted from the packet storage means, this is determined according to the priority. Mediation, and a more flexible system can be constructed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of a network in which core routers are arranged in a first exemplary embodiment of the present invention.
FIG. 2 is a block diagram showing an outline of a configuration of a first core router in the first embodiment.
FIG. 3 is a block diagram showing the configuration of a first preprocessing unit in the first embodiment.
FIG. 4 is a block diagram showing a configuration of a buffer control unit provided in the first input buffer.
FIG. 5 is a block diagram conceptually showing the relationship between the input traffic volume and the output traffic volume of the first core router in the first embodiment.
FIG. 6 is a block diagram showing an outline of a configuration of a first core router in the second embodiment.
FIG. 7 is a block diagram showing a configuration of a first preprocessing unit in the second embodiment.
FIG. 8 is a block diagram showing a configuration of a first input buffer in the second embodiment.
FIG. 9 is a block diagram showing the configuration of a buffer control unit provided in the first input buffer in the second embodiment.
FIG. 10 is a block diagram showing the configuration of a scheduler in the second embodiment.
FIG. 11 is a block diagram conceptually showing the relationship between the input traffic volume and the output traffic volume of the first core router in the second embodiment.
FIG. 12 is a block diagram showing an outline of a network in which a conventional core router and edge router are arranged.
FIG. 13 is a block diagram conceptually showing the relationship between the input traffic volume and the output traffic volume of a conventional core router.
FIG. 14 is a block diagram showing a configuration of a conventional core router.
[Explanation of symbols]
101 IP network
102₁~ 102_Three  1st to 3rd access networks
103 Core network
104₁~ 104_Three  First to third customer premises equipment
105₁, 105₂  First and second edge routers
106₁106A₁  First core router
106₂  Second core router
111₁~ 111_N  1st to Nth input ports
112₁~ 112_N201₁~ 201_N  1st to Nth pre-processing units
113₁~ 113_N, 202₁~ 202_N  1st to Nth input buffers
114 switch
115, 203 scheduler
116₁~ 116_M  1st to Mth output ports
117₁~ 117_M  First to Mth output port queues
120₁~ 120_M, 222₁₁~ 222_XM  Header inspection part
121, 223 Buffer control unit
127 control unit
132, 212₁~ 212_Four  Police
133, 213₁~ 213_Four  Marker
221₁₁~ 221_XM  11th to XM queues

Claims (4)

Disposed packets flowing per unit time for each of a plurality of inlet-side transmission path which is defined individually, the packet packet outflow amount per unit time is respectively toward the outflow side transmission path which is defined separately, respectively A packet receiving means for receiving;
Outflow packets per unit time are defined in advance for each inflow side transmission path among packets that are arranged corresponding to each of the plurality of inflow side transmission paths and that have passed through the corresponding inflow side transmission path received by the packet receiving unit. an identifier adding means for selectively adding an identifier to the inflow packets to distinguish between the amount of pre-defining the amount in excess of the amount that is,
Said plurality of arranged corresponding to each of the inlet-side transmission path, stores the selectively added to the after each packet identifier to each order of arrival at the identifier adding means, corresponding to each of the plurality of outlet-side transmission line Packet storage means provided as
The packet is arranged corresponding to each of the plurality of inflow side transmission paths, and the packet at the head position stored in each of these packet storage means is checked, and within the range of the packet outflow amount per unit time of the outflow side transmission path Then, a packet extracting means for preferentially extracting packets for which the outflow amount per unit time is secured by the identifier, per unit time;
A packet transfer system comprising: packet sending means for sending a packet taken out by each packet take-out means of the plurality of inflow side transmission paths to a corresponding one of the plurality of outflow side transmission paths. Disposed packets flowing per unit time for each of a plurality of inlet-side transmission path which is defined individually, the packet packet outflow amount per unit time is respectively toward the outflow side transmission path which is defined separately, respectively A packet receiving means for receiving;
Outflow packets per unit time are defined in advance for each inflow side transmission path among packets that are arranged corresponding to each of the plurality of inflow side transmission paths and that have passed through the corresponding inflow side transmission path received by the packet receiving unit. an identifier adding means for selectively adding an identifier to the inflow packets to distinguish between the amount of pre-defining the amount in excess of the amount that is,
Said plurality of arranged corresponding to each of the inlet-side transmission path, stores the selectively added to the after each packet identifier to each order of arrival at the identifier adding means, corresponding to each of the plurality of outlet-side transmission line Packet storage means provided as
Extraction priority registration means for registering the priority when packets extracted from these packet storage means compete for extraction for each inflow side transmission path;
A packet is placed corresponding to each of the plurality of inflow side transmission paths, and the packet at the head position stored in the packet storage means is checked, and within the range of the packet outflow amount per unit time of the outflow side transmission path Thus, when a packet in which the outflow amount per unit time is secured by the identifier is preferentially taken out every unit time, the packet in which the outflow amount per unit time is secured is registered in this takeout priority registration means. Packet extraction means for preferentially extracting packets with high extraction priority;
A packet transfer system comprising: packet sending means for sending a packet taken out by each packet take-out means of the plurality of inflow side transmission paths to a corresponding one of the plurality of outflow side transmission paths. The identifier adding means assigns identifiers for the amount of outflow per unit time exceeding the amount reserved in advance for each inflow side transmission path among the packets that have passed through each inflow side transmission path received by the packet receiving means. 3. The packet transfer system according to claim 1 , wherein the packet transfer system is added. The identifier adding means adds an identifier for the amount of outflow per unit time that is secured in advance for each inflow side transmission path among the packets that have passed through each inflow side transmission path received by the packet receiving means. The packet transfer system according to claim 1 or 2, characterized in that

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