CN107566294B - Network storm suppression method applicable to IEC62439 standard - Google Patents
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Abstract
The invention discloses a network storm suppression method applicable to IEC62439 standard. The storm filtering link is added on a receiving and transmitting link of the network equipment, the IEC62439 protocol label is detected and identified, and the storm filtering is carried out according to the original network message content. The PRP and HSR redundant networks described in IEC62439 both require that a protocol tag with a frame number is added on the basis of an original network packet, and the insertion of the protocol tag is generally completed by a hardware coprocessor of the device, so that the packets actually sent to the network and the original packets differ in content. The method can automatically identify the IEC62439 protocol label, and identify and filter the network storm by comparing the original message contents, thereby improving the availability and the robustness of the whole network equipment.
Description
Technical Field
The invention belongs to a network storm suppression method applicable to IEC62439 standard in the field of industrial control and industrial communication, and particularly relates to a network storm suppression method applicable to a high-reliability automation network in the IEC62439 standard.
Background
The traditional substation automation system has the defects of independent and stacked functions, lack of reasonable integrated application and cooperative operation, poor data sharing capability and low utilization rate. The digital transformer substation is the development direction of the automatic system of the current transformer substation, and particularly the international standard (IEC 61850) of the communication network and the system of the transformer substation is issued, so that the standard specification is provided for the construction of the digital transformer substation, and the development of the application construction of the digital transformer substation is promoted.
In digital substations, ethernet is the most dominant communication medium. The power system controls the protection equipment, and the communication function is increasingly realized through the Ethernet. Reliability requirements of power system applications are extremely high, and therefore, a redundant network is generally adopted to ensure the reliability of a communication system. IEC62439 proposes a highly reliable industrial automation communication network standard, which saves software processing load while ensuring reliability, and is currently the most common standard for power system digital station communication networks in the world.
The IEC62439 standard includes two sub-standards of PRP (Parallel Redundancy Protocol) and HSR (High-availability lossless Redundancy), which correspond to the topology structures of the star and the ring network, respectively. No matter what networking mode, once a network storm occurs, a large number of repeated invalid messages fill the network, and the performance of other equipment in the network is obviously reduced; compared with a point-to-point networking mode, the method has a larger influence range and more serious consequences.
Network storms may have several causes: 1. unreasonable network loops; 2. network device failure, 3, virus attack. According to the principle of information theory, two identical messages and the latter one do not carry any new information, so that the network storm is characterized in that a large number of repeated messages appear in the network. These repeated messages not only crowd the available network bandwidth, but also load the processor of the receiving device, which may seriously cause the device to fail to operate properly. The cause of the network storm is complex and difficult to fundamentally stop, but the consequence of the network storm is serious, and the prevention and control of the network storm are particularly important for the IEC62439 network requiring high reliability.
Furthermore, in the IEC62439 network, the conventional network storm prevention function may fail for the following reasons: 1. The IEC62439 message label comprises a frame number field, the value range of the field is 0-65535, and each frame is increased progressively. The content of any two IEC62439 messages is therefore different, leading to failure of the mechanism for detecting network storms from the same message. 2. Storm messages in the IEC62439 network may appear to be intermittent, that is, normal messages and storm messages arrive alternately, which increases the difficulty of identification and filtering.
At present, the digital transformer substation mainly has the following technical means for preventing network storm from causing harm:
1. the switching device supports STP (Spanning Tree Protocol), logically breaks a loop, and prevents a broadcast storm of a two-layer network from occurring. This approach can suppress the storm caused by the network loop from the source, but cannot identify the network storm that may occur when the network device fails.
2. The exchange equipment prevents the network storm by setting the service priority and limiting the port flow. First, if the type of the storm packet belongs to the high priority, the switching device cannot limit the forwarding of the storm packet, and even if the storm packet belongs to the low priority, although the forwarding of the normal high priority service packet is not affected, the receiving device may receive a large amount of storm packets at the same time, which consumes the resources of the processor, and may cause the device to be abnormal.
3. The switching device divides a VLAN (Virtual Local Area Network). VLAN is an emerging data exchange technique that logically divides lan devices into segments to implement virtual workgroups. The method can only reduce the probability of the network storm diffusion, and cannot fundamentally prevent and treat the network storm.
4. The receiving device processor identifies and filters the network storm by comparing whether the messages are the same. In this way, a certain storm filtering function can be achieved. However, since the length of the network message may be as high as 1500 bytes, a large amount of processor resources are required for storing and comparing the message, and the case where the normal message and the storm message arrive at intervals or the case where multiple network storms exist in the network cannot be processed.
In conclusion, the existing technical means for storm prevention and control have no targeted measures for the IEC62439 network, so that the efficiency is low and the effect is not obvious.
Disclosure of Invention
The invention aims to provide a network storm suppression method suitable for IEC62439 standard, which can realize a network storm filtering function with high efficiency and low consumption and improve the survival capability of secondary equipment in a complex network environment.
In order to achieve the above purpose, the solution of the invention is:
the invention is suitable for the network storm restraining method of IEC62439 standard, and the storm filtering link is added on the receiving and transmitting link of the network equipment to detect and identify the IEC62439 protocol label and carry out the storm filtering according to the original network message content.
The storm filtering method of the invention comprises the following steps:
(1) caching the received network message, and identifying information such as a destination address, a source address, a type, a length, a redundancy check code, whether a VLAN label exists or not according to the frame format of the Ethernet;
(2) according to the format definitions of the data frames of the PRP and the HSR, retrieving the received message, removing the protocol label of the PRP/HSR and the redundancy check code of the Ethernet message, and transmitting the residual data sequence to a storm filtering unit;
(3) the storm filtering unit does not have the probability of missed detection and false detection by accurately comparing the original message content according to the length;
(4) the storm filtering unit checks whether the same elements exist in the historical message cache queue according to the content and the length of the latest message, if the same elements exist, the current message is judged to be the storm message, and the storm message is directly discarded; if the same element does not exist, the message is transmitted to a lower-level processing unit;
(5) after storm identification and processing are completed, the storm filtering unit fills the latest message into the cache queue and removes the oldest message in the cache queue out of the queue.
According to the characteristics of the IEC62439 network message, the invention purposefully realizes the tag elimination of the IEC62439 message and the comparison of the original message content, and can be realized by embedded hardware such as FPGA (field programmable gate array), thereby not reducing the network bandwidth and not damaging the message content. In addition, the method can flexibly set the frame number of the historical message cache according to the actual requirement, and can give consideration to resources and performance. Thirdly, the method can be flexibly deployed on network terminal equipment or in network transmission equipment, and has small influence on the existing equipment. By applying the content of the invention to the IEC62439 network equipment, the capacity of the equipment for resisting network storms can be obviously enhanced on the premise of not consuming software resources, the difficulty of network construction of a digital substation is reduced, and the reliability and maintainability of the whole system are improved. The invention has the following characteristics:
1) the network storm filtering effect realized by the invention aims at the characteristics of IEC62439 network, and is simple, efficient and easy to realize;
2) the present invention can be applied to a terminal device and a network device of IEC 62439;
3) the functions implemented by the present invention do not consume processor resources.
Drawings
FIG. 1 is a system configuration diagram of an application example of the present invention;
FIG. 2 is a schematic diagram of a format of a PRP network packet;
fig. 3 is a schematic diagram of the format of an HSR network message;
FIG. 4 is a state transition diagram of an embodiment of an application of the present invention;
FIG. 5 is a diagram illustrating the updating of a message buffer queue according to the present invention;
Detailed Description
The invention provides a network storm suppression method applicable to IEC62439 standard, which detects and identifies IEC62439 protocol labels by adding a storm filtering link on a network equipment transmitting-receiving link and carries out storm filtering according to the content of original network messages. Namely, a storm isolation functional component supporting IEC62439 standard is added between a network transceiver and a data link layer processing unit, and the functions of identifying and filtering storms are realized by accurately comparing the original message contents according to the length.
The IEC62439 standard defines two kinds of redundant networks, namely a PRP (Parallel Redundancy Protocol) network and an HSR (High-availability lossless Redundancy) network. The contents of the protocol tags of the two networks are different from the positions in the message, and therefore, a distinguishing process is required.
The invention is suitable for a network storm suppression method of a high-reliability automation network described by IEC62439 standard, and the storm filtering method comprises the following steps:
(1) caching the received network message, and identifying information such as a destination address, a source address, a type, a length, a redundancy check code, whether a VLAN label exists or not according to the frame format of the Ethernet;
(2) according to the format definitions of PRP (Parallel Redundancy Protocol) and HSR (High-availability self Redundancy) data frames, retrieving the received message, removing the PRP/HSR Protocol label and the Redundancy check code of the Ethernet message, and transmitting the residual data sequence to a storm filtering unit;
(3) the storm filtering unit does not have the probability of missed detection and false detection by accurately comparing the original message content according to the length;
(4) the storm filtering unit checks whether the same elements exist in the historical message cache queue according to the content and the length of the latest message, if the same elements exist, the current message is judged to be the storm message, and the storm message is directly discarded; if the same element does not exist, the message is transmitted to a lower-level processing unit;
(5) after storm identification and processing are completed, the storm filtering unit fills the latest message into the cache queue and removes the oldest message in the cache queue out of the queue.
The invention compares the original message content except IEC62439 protocol label and Ethernet check code according to the message length, as the basis for identifying and filtering storm message.
The invention fills the latest received message into the buffer queue after completing comparison, and removes the earliest received message from the queue when the buffer queue is full.
According to the latest message, if the historical messages with the same content are found in the cache queue, the latest message is judged to be a storm message, and the filtering operation is executed. The storm filtering function of the invention is deployed in the sending and receiving paths of the network terminal equipment as required. The storm filtering function is connected in series in the independent network equipment and is used as a part of a network communication path to play the roles of isolating network faults and preventing storm diffusion.
In this embodiment, a Zynq7015 series SOC (System On Chip) Chip of Xilinx corporation is used as the processor. ZYNQ7015 integrates two ARM cortex A9 cores and one Artix7 series FPGA into one chip. In this embodiment, the system configuration of the terminal device supporting the IEC62439 network is shown in fig. 1. The network Layer of the device is realized by software (ARM processor), the link Layer (including link redundancy entity and storm filtering module) is realized by FPGA (Field Programmable gate Array), and the network transceiver is realized by external PHY (Physical Layer network Physical Layer) chip.
The logical functions of the device are simplified according to the seven-layer model definition of the standard OSI (Open System interconnection model), and four layers of an application layer, a network layer, a data link layer and a physical layer are reserved. The ARM in the equipment realizes the functions of an application layer and a network layer, the FPGA realizes the function of a data link layer, and the PHY chip and the network cable belong to the physical layer of the system.
The functional implementation of the application layer and the network layer belongs to the software category, and in this example, the functional implementation of the data link layer is described in detail. The LRE (link Redundancy Entity) is responsible for implementing the redundant packet processing function labeled by IEC62439, and is specifically implemented as follows:
and a sending link: and the link redundancy entity receives the original network message from the network layer, inserts the protocol label of IEC62439, recalculates CRC and sends the CRC to the downstream functional unit. For a PRR network, the position of the protocol label is located at the end of the network message and in front of the frame check code, and the format of the PRP message is shown in fig. 2. For an HSR network, the protocol label is located behind the source address of the ethernet message, and the format of the HSR message is shown in fig. 3. After the link redundancy entity processes the network layer/application layer message, a dual-network redundancy message is generated, the two redundancy messages are different except for the network path field in the IEC62439 label, and the contents of other messages (except the CRC code) are completely the same.
Receiving a link: the link redundancy entity detects the message arriving in the dual-network, and discards the message with the same sequence number arriving in the AB dual-network according to the protocol label, so that the network layer (application layer) can only receive one copy of data.
Storm filtering: in this example, as shown in fig. 1, the storm filtering function is located between a Link Redundancy Entity (LRE) and a network transceiver controller. The message processed by the storm filtering module is in a form of carrying an IEC62439 protocol label, and a complete message is regarded as a binary sequence which can be expressed as the following binomial expression:
due to the existence of IEC62439 label, before identifying whether the message is a storm message, the protocol label field and the network message checksum need to be removed first, and the generated binomial is as follows:
wherein, IEC62439 label is 48 bits, and the checksum is 32 bits, so have:
the maximum length of the ethernet packet is generally 1518Byte, so that one unit depth of the packet buffer queue can be set to 2048Byte, which can meet the length requirement of any ethernet packet. The working flow of the storm filtering module realized by the FPGA is shown in FIG. 4, when the FPGA caches the current message, the FPGA reads the content in the history cache and compares the content with the content of the current message, and if the content of any field or length is inconsistent, the current message is indicated to be inconsistent with the history record; after the retrieval is finished, a history message exists in the history cache, the history message is compared byte by byte according to the length, the data content of the history message is completely consistent with that of the current message, namely the current message is judged to be the same as the history message, namely the current message is a storm message, and the FPGA discards the storm message. If the same element is not detected in the cache, the message is not a storm message, and the FPGA submits the message to an application layer. In this example, to increase the comparison speed, a 64-bit wide RAM group with 32 identical structures is used as the hardware implementation of the packet buffer queue, and the driving clock of the RAM is 100M. Therefore, in each clock cycle, the comparison of the 8Byte data of the current message and the historical 32 messages can be realized, the bandwidth of the comparison circuit is as high as 6.4Gbps, and the flow requirement is completely met.
The history buffer of the storm filtering module has a self-updating function, namely, the FPGA receives the latest message, after the retrieval/judgment process is completed, the current message is filled into the buffer queue, and the oldest (received first in time) message in the buffer queue is moved out of the buffer queue, so that the message content in the buffer queue is the record of the latest received message, and the figure 5 is a schematic diagram of the message buffer queue before and after updating, so that visual comparison can be obtained.
The depth of the historical message cache queue determines the type of the storm message which can be filtered maximally, and the type of the storm message can be flexibly set according to application requirements. Taking a buffer queue with a depth of N as an example, at most N different packets may exist in the buffer queue. As mentioned above, because the algorithm of full comparison is adopted, there is no probability of missed detection or false detection in the whole comparison process. Since N historical messages are cached, under the maximization condition, the equipment sequentially and circularly receives N storm messages, and the N storm messages can be filtered according to the description of the self-learning capability of the historical message cache queue. If the device sequentially and circularly receives the N +1 storm messages, the filtering mechanism cannot take effect because the same message cannot be found in the cache queue.
After the message passes through the storm filtering module, the current message is selected to be continuously transmitted to the next level or directly discarded according to the result of storm filtering, so that the storm suppression function in the IEC62439 network is realized.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.
Claims (6)
1. A network storm suppression method applicable to IEC62439 standard is characterized by comprising the following steps: the method comprises the steps of detecting and identifying IEC62439 protocol labels by adding a storm filtering link on a network equipment transmitting-receiving link, and carrying out storm filtering according to the content of original network messages;
the storm filtering method comprises the following steps:
(1) caching the received network message, and identifying a destination address, a source address, a type, a length, a redundancy check code and whether VLAN label information exists according to the frame format of the Ethernet;
(2) according to the format definitions of the data frames of the PRP and the HSR, retrieving the received message, removing the protocol label of the PRP/HSR and the redundancy check code of the Ethernet message, and transmitting the residual data sequence to a storm filtering unit;
(3) the storm filtering unit does not have the probability of missed detection and false detection according to the accurate comparison of the original message content according to the length;
(4) the storm filtering unit checks whether the same elements exist in the historical message cache queue according to the content and the length of the latest message, if the same elements exist, the current message is judged to be the storm message, and the storm message is directly discarded; if the same element does not exist, the message is transmitted to a lower-level processing unit;
(5) after storm identification and processing are completed, the storm filtering unit fills the latest message into the cache queue and removes the oldest message in the cache queue out of the queue.
2. The method for suppressing network storm according to IEC62439 standard as recited in claim 1, wherein: and fully comparing the original contents of the messages except the IEC62439 protocol label and the Ethernet check code according to the message length to serve as a basis for identifying and filtering storm messages.
3. The method for suppressing network storm according to IEC62439 standard as recited in claim 1, wherein: and after the comparison of the latest received message is completed, filling the latest received message into a buffer queue, and when the buffer queue is full, removing the earliest received message from the queue.
4. The method for suppressing network storm according to IEC62439 standard as recited in claim 1, wherein: and according to the latest message, if the historical message with the same content is found in the cache queue, judging that the latest message is a storm message, and executing filtering operation.
5. The method for suppressing network storm according to IEC62439 standard as recited in claim 1, wherein: the storm filtering function is deployed in the transmission and reception paths of the network terminal device as needed.
6. The method for suppressing network storm according to IEC62439 standard as recited in claim 1, wherein: the storm filtering function is connected in series in the independent network equipment and is used as a part of a network communication path to play the roles of isolating network faults and preventing storm diffusion.
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| CN111064593A (en) * | 2018-10-17 | 2020-04-24 | 中车株洲电力机车研究所有限公司 | Network topology redundant communication system and network topology redundant communication method |
| CN114500117B (en) * | 2022-04-15 | 2022-07-05 | 北京全路通信信号研究设计院集团有限公司 | Looped network Master configuration error judgment method and device based on looped network storm flow characteristics |
| CN115499359B (en) * | 2022-09-15 | 2023-12-29 | 四川灵通电讯有限公司 | Improved method for wasting link resources based on standard HSR protocol |
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