JP2018117270A - Processing unit and method of processing packet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that, in a processing unit including a plurality of communication ports, if a storm occurs in one communication port and packets cannot be transmitted and received, the processing load of a CPU in the processing unit rapidly increases, so that other communication ports also cannot transmit and receive packets.SOLUTION: On a communication port where a storm occurs, a threshold is provided to at least one of the total number and the total data capacity of packets received for each prescribed cycle time, and, when received packets exceed the threshold, the transmission and reception of packets are stopped so that the processing load of a CPU in a processing unit is reduced and the transmission and reception of packets are continued on other communication ports.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a processing apparatus on a network having a plurality of communication ports and a packet processing method.

  When a processing device or switching hub connected to the network fails, a large number of packets may be erroneously transmitted on the network by broadcast. If another processing device on the network that continues control receives the large number of packets, the load of reception processing increases rapidly, and control may not be continued.

  As a countermeasure, Patent Document 1 discloses a technique for discarding a received packet from a communication partner and continuing control of a control device without causing a system down when there is excessive communication due to a Dos attack or the like. Yes. Therefore, the technique disclosed in Patent Document 1 is to continue control by thinning out received packets when a storm occurs.

JP 2010-154576 A

When a broadcast storm (hereinafter abbreviated as “storm”) occurs, a large number of packets are broadcast on the network to a processing device with multiple communication ports, and the processing devices on that network receive a large number of packets. As a result, the processing load of the processing device increases rapidly, delaying the processing operation, and packet reception omission occurs, so that the control operation is finally stopped and the control becomes impossible.
As a countermeasure, even if a processing device having a plurality of communication ports receives a large number of packets at one communication port, a method of blocking the reception of the packets and continuing control at another communication port is considered.

  In order to solve the above-described problems, the present invention is a processing device having a plurality of communication ports, wherein the plurality of communication ports are connected to different networks, and for each communication port, packets received at a certain period of time are received. A threshold is set for at least one of the total number and the total packet capacity, and the threshold is exceeded when it is detected that a packet per fixed period time received by any one of the plurality of communication ports exceeds the threshold. During the period, transmission / reception of packets by the communication port is stopped.

  According to the present invention, when a storm occurs, the reception of the packet from the communication port that received the storm is cut off, and the reception of the packet from the communication port that does not generate the storm is continued. Control can be continued.

FIG. 1 is a diagram showing the configuration of a system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an architecture configuration of software according to the embodiment of the present invention. FIG. 3 is a diagram illustrating the flow of detection, continuation, and cancellation of a storm. FIG. 4 is a diagram illustrating a method for detecting and canceling a storm from the viewpoint of a software area and a hardware area. FIG. 5 is a diagram showing whether to process or discard the packet depending on the type of packet.

  As embodiments for carrying out the present invention, embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating a configuration of a system using a processing apparatus according to an embodiment of the present invention.
Each processing device has a plurality of communication ports, and in the embodiment, the processing device A 101 and the processing device B 102 have two communication ports 108 and 109, 110 and 111, respectively.

  The processing device A 101 and the processing device B 102 are connected to different networks 106 and 107, respectively. The two communication ports 108 and 109 of the processing apparatus A 101 are connected to the network 106 and the network 107, respectively, and the two communication ports 110 and 111 of the processing apparatus B 102 are connected to the network 106 and the network 107, respectively. Similarly, the processing device C103, the processing device D104, and the processing device E105 are connected to different networks 106 and 107, respectively.

  The processing apparatus A 101 transmits and receives the same data as a packet to and from different networks 106 and 107 through different communication ports 108 and 109. Similarly, the other processing devices (B102, C103, D104, and E105) transmit and receive the same data as packets on different networks 106 and 107 through different communication ports. That is, by transmitting the same data to different networks 106 and 107, even if the packet does not reach one communication port, if the packet arrives at the other communication port, it can be controlled as a processing device. . As an example of adopting such a system configuration, there is a case where the network is made redundant (duplex) as in a railway signal system, for example.

  However, when a broadcast storm (hereinafter abbreviated as “storm”) occurs, each processing device receives a large amount of packets, and due to a decrease in hardware performance, a large amount of packets cannot be processed and the processing device stops. Fall into a situation. Therefore, even if a storm occurs on one network, it is a separate network so that it does not affect the other network, but there are also communication ports where the processing device itself cannot process and a storm has not occurred. It cannot be processed.

  Therefore, in order to deal with such a situation, the communication port connected to the network where the storm has occurred is blocked so that the packet does not flow, and the other communication port can be controlled.

FIG. 2 is a diagram illustrating an exemplary architecture configuration of software included in each processing apparatus.
Examples of software included in the processing device 201 include an application 202, middleware 203, a protocol manager 204 that processes communication, a driver 205 that controls communication LSIs 208 and 209, and an OS 206 that controls the operation of the CPU 207. Examples of hardware included in the processing device 201 include a CPU 207 and communication LSIs 208 and 209 that control packet transmission and reception. That is, the processing apparatus includes a plurality of communication ports and has as many communication LSIs as the number of communication ports. In the embodiment, it is assumed that the processing apparatus 201 includes two communication LSIs 208 and 209. Note that a memory that should be hardware is omitted.

  When at least one of the total number of packets and the total data capacity exceeds a certain threshold value within a certain period of time on the communication port, the processing device determines that a storm has been detected and stops packet transmission / reception. Further, when the processing device continues to detect a storm within a certain period of time, it continues to transmit and receive packets. Then, when at least one of the total number of packets and the total data capacity falls below a threshold value on the communication port, the processing device determines that the storm has been released and resumes transmission / reception of packets.

FIG. 3 is a diagram showing a flow of detection, continuation, and cancellation when the storm occurs.
The occurrence of a storm is monitored within the cycle time T0. If no storm occurs at the end of the cycle time T0, the presence or absence of the storm is continuously monitored at the cycle time T0. When at least one of the total number of packets and the total data capacity exceeds a certain threshold on a certain communication port, it is determined that a storm has occurred, and transmission / reception of packets on the communication port exceeding the threshold is stopped. Here, the cycle time T0 and the threshold need to be determined according to the hardware performance of the processing device and the number of packets flowing on the system, and are determined individually according to the system.

  Next, storm continuation will be described. After the occurrence of the storm, the continuation of the storm state is monitored using the cycle time T1. When at least one of the total number of packets and the total data capacity continues to exceed the threshold value, it is determined that the storm is continuing, and the presence or absence of the storm is continuously monitored within the cycle time T1. When at least one of the total number of packets and the total data capacity falls below the threshold value, the storm is stopped, it is determined that the storm has been released, and packet transmission / reception is resumed from the end of the cycle time T1. Thereafter, the presence / absence of a storm is continuously monitored at the cycle time T0.

  In this way, the communication port that detects the storm stops sending and receiving packets until the storm is canceled, but the communication port that does not detect the storm is not affected by the communication port that detected the storm, The packet transmission / reception can be continued. Here, the relationship between the cycle period T0 for monitoring the occurrence of a storm and the cycle period T1 for monitoring the continuation of the storm state is T0 ≦ T1, and the reason why T1 is made larger than T0 is that the storm state occurs after the storm occurs. This is a measure for suppressing frequent changes in whether or not there is a change.

FIG. 4 is a diagram showing a storm detection and release method according to the present invention from the viewpoint of the software area 401 and the hardware area 402.
The occurrence of a storm is detected by monitoring the number of received packets stored in the reception buffer 403 managed in the software area 401 and the number of received packets stored in the reception FIFO 404 managed in the hardware area 402.

  In the case of no storm occurrence shown in (1) of FIG. 4, after receiving the packet 405, it is stored in the reception FIFO 404, transferred from the hardware area 402 to the software area 401, and stored in the reception buffer 403. To do. Since no storm has occurred, all packets 405 are stored in the reception buffer 403.

  When a storm occurs as shown in (2) of FIG. 4, a large amount of packets 405 are to be stored in the reception FIFO 404. However, when the reception FIFO 404 overflows, packets corresponding to “A” in (2) of FIG. (Such discard processing is executed, for example, by interrupt processing due to overflow detection). Packets 405 that are not discarded are stored in the reception buffer 403. As the threshold for storm detection, the total number of packets 413 and discard packets 412 stored in the reception buffer 403 (that is, the number of packets received by the reception FIFO 404) is used, or the total data capacity of the reception packets At least one is used.

  When the transmission / reception of the packet is stopped after the storm detection shown in (3) of FIG. 4, the reception FIFO 404 of the hardware 402 receives the packet 405, but is not stored in the reception buffer 403, and is not stored in (3) of FIG. ) Discard all packets 405 indicated as “B”.

  After the storm cancellation shown in (4) of FIG. 4, the received packet 405 is transferred from the reception FIFO 404 to the reception buffer 403.

FIG. 5 is a diagram showing whether to process or discard the packet depending on the type of packet to be received.
The processing device 501 includes a communication LSI 502 and a CPU 503. The communication LSI 502 has a reception FIFO 505 as a memory, and the CPU 503 has a memory 504 and a reception buffer 506 for receiving a packet.

  The packet types include an abnormal packet 507, a packet 508 not addressed to the processing device 501, and a packet 509 addressed to the processing device 501.

  The abnormal packet 507 includes a CRC error packet and a short packet. When the abnormal packet 507 is stored in the reception FIFO 505, the communication LSI 502 determines that it is an abnormal packet and discards it.

  The packet 508 not addressed to the processing device 501 includes a UDP packet, a TCP packet, and the like. When the packet 508 is stored in the memory 504, the CPU 503 determines that the packet is not addressed to the processing device 501, and discards the packet.

  The packet 509 addressed to the processing device 501 includes a UDP packet, a TCP packet, and the like. The packet 509 is stored in the reception buffer 506, and the CPU 503 executes processing.

  In determining whether the threshold for storm detection has been exceeded, as described above, the received FIFO 505 receives at least the total number of packets and the total data capacity without distinguishing between discarded packets and processed packets. Calculate one.

  As described above, according to the embodiment of the present invention, when a storm occurs, transmission / reception of packets on the communication port is stopped, and transmission / reception of packets on the communication port where no storm has occurred is continued.

101 Processing device A
102 Processing device B
103 Processing device C
104 Processing device D
105 Processor E
106, 107 Network 108, 109 Communication port 110, 111 of processing device A Communication port 201, 501 of processing device B Processing device 202 Application 203 Middleware 204 Protocol manager 205 Driver 206 OS
207, 503 CPU
208, 209, 502 Communication LSI
401 Software area 402 Hardware area 403, 506 Reception buffer 404, 505 Reception FIFO
405 Received packet 504 Memory 507 Abnormal packet 508 Packet 509 not addressed to processing device 501 Packet addressed to processing device 501

Claims (6)

A processing device having a plurality of communication ports,
The plurality of communication ports are connected to different networks,
For each communication port, a threshold is provided for at least one of the total number of packets received per fixed period time and the total packet capacity,
When it is detected that the packet per fixed period time received by any one of the plurality of communication ports exceeds the threshold value, packet transmission / reception by the communication port is stopped during the period exceeding the threshold value. The processing apparatus characterized by performing. The processing apparatus according to claim 1,
For each communication port, always monitor the packet sent from the network,
The processing apparatus, wherein when the packet sent to the communication port that has stopped transmission / reception of the packet falls below the threshold, the communication port resumes transmission / reception of the packet. The processing apparatus according to claim 1 or 2,
The processing device, wherein the communication port is configured by a communication LSI having a reception FIFO. The processing apparatus according to any one of claims 1 to 3,
The processing apparatus according to claim 1, wherein the different network is a redundant network used for a railway signal system. A method for processing packets sent and received for different networks,
Providing a threshold for at least one of the total number of packets and total packet capacity received per fixed period time for each different network;
Constantly monitoring the packets received for each different network;
Detecting that the packet received for each of the different networks exceeds the threshold per certain period of time, stopping the transmission and reception of packets with the network that transmitted the packet during the period exceeding the threshold; A method for processing packets having The packet processing method according to claim 5, comprising:
A packet processing method further comprising a step of resuming transmission / reception of a packet with the network when a packet transmitted by the network that has stopped transmission / reception of the packet falls below the threshold.