KR102404112B1 - Network device and method for handling failure of sdn controller server in software defined network enviroment - Google Patents

Abstract

A method for handling in a network device when an SDN controller server failure occurs in a software-defined network environment is provided. The method includes the steps of: receiving, by a plurality of network devices connected to the SDN controller server, a first flow rule from the SDN controller server; processing a packet based on the first flow rule in a state in which the connection to the SDN controller server is normal; periodically receiving and storing a second flow rule different from the first flow rule from the SDN controller server; checking whether at least one network device among the plurality of network devices is disconnected from the SDN controller server; and processing a packet based on the second flow rule when the connection is disconnected as a result of the check, wherein the plurality of network devices process the packet based on any one of the first flow rule and the second flow rule do.

Description

Network equipment and method for handling SDN controller server failure in software-defined network environment

The present invention relates to a network equipment and method for handling an SDN controller server failure in a software-defined network environment.

SDN (Software Defined Networking, hereinafter SDN) technology refers to a technology that manages all devices in a network by an intelligent central management system. The SDN technology has the advantage of being able to develop and provide various functions compared to the existing network structure by having the controller provided in the form of software handle the control operation related to packet processing performed by itself in the existing hardware type network equipment instead.

On the other hand, one of the biggest weaknesses of the centralized control system through the SDN controller server is the problem caused by the failure occurring in the SDN controller server itself.

In addition, system stability can be improved through redundancy of the SDN controller server, but in the worst case, if all SDN controller servers fail, this affects the entire network system.

In addition, from the point of view of actual users, when a system failure such as the SDN controller occurs, network equipment such as a switch is often rebooted. .

Laid-open Patent Publication No. 10-2016-0002270 (2014.06.30)

The problem to be solved by the present invention is that, in a normal connection state between the SDN controller server and network equipment, packets are processed based on a general flow rule, but when the switch is rebooted or the connection between the controller and the switch is cut off An object of the present invention is to provide a network device and method for processing an SDN controller server failure in a software-defined network environment, which can continuously provide a service to a host by applying a stored flow rule.

However, the problems to be solved by the present invention are not limited to the problems described above, and other problems may exist.

According to the first aspect of the present invention for solving the above problems, a method for processing in a network device when an SDN controller server failure occurs in a software-defined network environment is provided by a plurality of network devices connected to the SDN controller server from the SDN controller server. 1 Receiving a flow rule; processing a packet based on the first flow rule in a state in which the connection to the SDN controller server is normal; periodically receiving and storing a second flow rule different from the first flow rule from the SDN controller server; checking whether at least one network device among the plurality of network devices is disconnected from the SDN controller server; and processing the packet based on the second flow rule when the connection is disconnected as a result of the check. In this case, the plurality of network devices process the packet based on any one of the first flow rule and the second flow rule.

In some embodiments of the present invention, the first flow rule may have a higher priority than the second flow rule in a state in which the plurality of network devices have a normal connection to the SDN controller server.

In some embodiments of the present invention. As the second flow rule is received and stored, the flow entry having the lowest priority included in the first flow rule is changed to have a higher priority than the flow entry having the highest priority included in the second flow rule can be

In some embodiments of the present invention, the step of periodically receiving and storing a second flow rule different from the first flow rule from the SDN controller server includes: As the SDN controller server periodically updates the second flow rule , the plurality of network devices may receive the updated second flow rule periodically and separately store it in an internal memory different from an area in which the first flow rule is stored.

In some embodiments of the present invention, the first flow rule may be deleted from the network equipment after a predetermined time has elapsed from the point in time when the connection with the SDN controller server is cut off.

In some embodiments of the present invention, the step of checking whether the connection with the SDN controller server is disconnected from at least one of the plurality of network devices includes the deletion of the first flow rule after the predetermined time has passed. Thereafter, it is possible to check whether the connection with the SDN controller server is disconnected through whether the second flow rule is applied.

According to some embodiments of the present invention, the method includes: re-receiving, by the network equipment, a first flow rule from the SDN controller server during packet processing based on the second flow rule; applying the first flow rule in place of the second flow rule; and processing the packet based on the re-received first flow rule.

In addition, the network equipment that handles the occurrence of an SDN controller server failure in a software-defined network environment according to the second aspect of the present invention includes at least one host and a communication module for transmitting and receiving packets to and from the SDN controller server, in the SDN-based network environment. and a memory in which a program for processing a packet by applying any one of the first and second flow rules according to whether a failure occurs, and a processor in which the program stored in the memory is stored. In this case, as the program is executed, the processor receives and applies a first flow rule from the SDN controller server through the communication module in a state in which the connection with the SDN controller server is normal, processes the packet, and performs the communication The module periodically receives and stores a second flow rule different from the first flow rule from the SDN controller server, and when the connection with the SDN controller server is cut off, the packet is processed based on the second flow rule.

A computer program according to another aspect of the present invention for solving the above problems is combined with a computer that is hardware to execute a processing method in a network device when an SDN controller server failure occurs in the software-defined network environment, and a computer readable record stored on the medium.

Other specific details of the invention are included in the detailed description and drawings.

According to the present invention described above, packet processing is possible even when the network equipment is disconnected from the SDN controller server or when the network equipment is rebooted, so that the host that is using the existing service can continue to use the service even in the event of a failure. .

In addition, the network equipment has the advantage of being able to minimize the occurrence of a failure by periodically receiving and storing flow information from the SDN controller server even in a general situation, and processing packets based on the stored flow information when a failure occurs.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a diagram for explaining the configuration of a software-defined network in an embodiment of the present invention.
2 is a flowchart of a processing method in a network device when an SDN controller server failure occurs according to an embodiment of the present invention.
3 is a diagram for explaining an example of storing first and second flow rules in a network device.
4 is a diagram for explaining the contents of the first flow rule in the network equipment being deleted due to a timeout.
5 is a diagram for explaining an example in an embodiment of the present invention.
6 is a diagram for explaining a network device according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains. It is provided to fully understand the scope of the present invention to those skilled in the art, and the present invention is only defined by the scope of the claims.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless otherwise specified in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components. Like reference numerals refer to like elements throughout, and "and/or" includes each and every combination of one or more of the recited elements. Although "first", "second", etc. are used to describe various elements, these elements are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first component mentioned below may be the second component within the spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein will have the meaning commonly understood by those of ordinary skill in the art to which this invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless specifically defined explicitly.

1 is a diagram for explaining the configuration of a software-defined network in an embodiment of the present invention.

Referring to FIG. 1 , a software defined network includes an SDN controller server 100 , a network device 200 , and a host 300 . In this case, the network device 200 and the host 300 may be referred to as a node, and a link means a connection between two nodes.

The SDN controller server 100 functions to manage the network equipment 200 , and centrally manages and controls a plurality of network equipment 200 . Specifically, the SDN controller server 100 includes software that functions such as topology management, packet processing-related path management, link discovery, and packet flow flow management. It may be implemented in a mounted form.

The network device 200 performs a function of processing a packet according to the control word of the SDN controller server 100 . In this case, an example of the network equipment 200 may be a mobile communication base station, a base station controller, a gateway device, a wired network switch, a router, and the like. However, for convenience of explanation, the following description will focus on the case where the network equipment 200 is an open flow switch, and the same reference numerals will be used.

In a software-defined network, the SDN controller server 100 and the network device 200 must exchange information with each other, and the OpenFlow protocol is widely used as a protocol for this purpose. That is, the OpenFlow protocol is a standard standard for communication between the SDN controller server 100 and the network equipment 200 .

More specifically, the network equipment 200 is largely divided into a software layer and a hardware layer.

The software layer exchanges information with the SDN controller server 100 through a secure channel. The secure channel is a communication channel between the network device 200 and the remote SDN controller server 100 , and information exchanged between the SDN controller server and the network device 200 is encrypted.

In the hardware layer, a flow table defines and processes a packet and includes statistical information related to the packet. The flow table consists of flow rules that define packet processing, and the flow rules are added by a flow-mod message generated by the SDN controller server 100 and transmitted to the network equipment 200 . , may be modified or deleted. The network device 200 processes the packet with reference to the flow table.

The flow table includes packet header information (Rule) defining a flow, action information (Action) defining packet processing, and statistical information (Stats) for each flow. Here, each row constituting the flow table is referred to as a flow entry.

The host 300 refers to a terminal corresponding to a lower layer of the network equipment 200 , and may be used to collectively refer to a client and a server. The host 300 may generate a packet for sending to another host through a software-defined network, and transmit the packet to the network device 200 through a port of a network interface.

For example, when the first host 300a wants to send a packet to the second host 300b, the first host 300a first generates a packet to be sent, and connects the packet to the first host 300a. It is transmitted to the network device 200 . When the network device 200 has a flow table regulating the processing of the corresponding packet, the network device 200 processes the packet according to the regulation.

However, when the network device 200 does not have a flow table related to the corresponding packet, the network device 200 transmits a packet-in message informing the SDN controller server 100 of the packet inflow.

The SDN controller server 100 generates a flow mode message regulating packet processing according to the operator's policy or a preset algorithm and transmits it to the network device 200, and the network device 200 transmits the flow changed by the flow mode message. Refers to the table and processes the corresponding packet.

Meanwhile, there are various paths through which the first host 300a can transmit a packet to the second host 300b. This is because, since a plurality of network devices 200 and hosts exist in the entire network, each node has a plurality of links. At this time, the SDN controller server 100 calculates an optimal path among a plurality of paths through which packets can be transmitted based on the entire network topology map. In addition, the SDN controller server 100 transmits information on the calculated optimal path to the network device 200 , and the network device 200 generally processes the packet through the optimal path.

Hereinafter, a processing method in the network equipment 200 when the SDN controller server 100 failure occurs in a software defined network environment according to an embodiment of the present invention will be described with reference to FIGS. 2 to 5 .

2 is a flowchart of a processing method in the network equipment 200 when a failure occurs in the SDN controller server 100 according to an embodiment of the present invention.

First, the SDN controller server 100 transmits a first flow rule to the plurality of network devices 200 , and the network device 200 receives the first flow rule ( S110 ). And in a state in which the connection to the SDN controller server 100 is normal, the network device 200 processes the packet based on the first flow rule (S120).

Here, the first flow rule should be understood to mean a network policy applied by the SDN controller server 100 in a software-defined network in a normal position in the industry. That is, the first flow rule is a flow rule applied while the SDN controller server 100 is connected, and a flow entry in which packet processing is centrally controlled by the SDN controller server 100 is defined.

As the network device 200 and the host 300 are registered or deleted, the SDN controller server 100 may dynamically transmit the first flow rule to the corresponding network device 200 to update or delete it. The first flow rule must be dynamically operated according to a situation in which the network topology is changed. Unlike the second flow rule recorded on the disk, the first flow rule is recorded in the memory.

In general, when the network device 200 is rebooted, the first flow rule received from the SDN controller server 100 is deleted from the memory, and as the network device 200 is connected to the SDN controller server 100 after rebooting is completed, the network device 200 ) receives the first flow rule again.

At this time, when the reboot is performed by the user, it is not a big problem because the user knows in advance that a temporary communication failure will occur. However, in the case of a reboot due to a system failure or when the connection is disconnected due to a failure due to the SDN controller server 100 , the SDN controller server 100 cannot control the network equipment 200 , and accordingly The service cannot be used until they are reconnected to each other.

An embodiment of the present invention enables the host 300 to continuously use the service by enabling packet processing through a separate flow rule even when the connection is disconnected due to a failure as well as when the user reboots. can do.

Specifically, the network equipment 200 periodically receives and stores a second flow rule different from the first flow rule from the SDN controller server 100 ( S130 ). In this case, the first flow rule and the second flow rule are not necessarily transmitted and received sequentially, but may be transmitted and received simultaneously. Meanwhile, in the description and drawings of the present invention, it has been described that the second flow rule is received after the first flow rule is received for convenience, but the present invention is not limited thereto.

FIG. 3 is a diagram for explaining an example of storing the first and second flow rules in the network device 200 .

Here, the second flow rule is a rule applied in a state in which the connection with the SND controller server 100 is cut off, and a flow entry directly corresponding to the network device 200 , that is, the L2 switch or the L3 switch is defined, and is different from the first flow rule. its character is different

The plurality of network devices 200 process a packet by applying only one of the first flow rule and the second flow rule.

In one embodiment, the first flow rule has a higher priority than the second flow rule in a state in which the plurality of network devices 200 are connected to the SDN controller server 100 . Accordingly, in a state in which the network device 200 stores the first flow rule and the second flow rule at the same time, as long as the first flow rule exists, the second flow rule is not applied and only the first flow rule is applied to process the packet. do.

Meanwhile, the SDN controller server 100 periodically updates the second flow rule so that the latest policy is maintained in the network device 200 and transmits it to the network device 200 , and the network device 200 transmits the updated second flow rule. Receive rules periodically. Upon receiving the second flow rule, the network device 200 may separately store the first flow rule in an internal memory different from the area in which it is stored. That is, the second flow rule is stored in the form of a file on the internal disk of the network device 200 .

Accordingly, even if the network equipment 200 is rebooted, unlike the first flow rule, since the file corresponding to the second flow rule stored in the internal disk is read and moved back to the memory, the connection with the SDN controller server 200 is Even in the disconnected state, the packet for the service of the host 300 may be processed by maintaining the second flow rule most suitable for packet processing.

Next, at least one of the plurality of network devices 200 checks whether the connection with the SDN controller server 100 is disconnected (S140), and when the connection is disconnected as a result of the check, based on the second flow rule The packet is processed (S150).

FIG. 4 is a diagram for explaining the contents of the first flow rule in the network device 200 being deleted due to a timeout.

In one embodiment, the first flow rule includes a timeout set by the SDN controller server 100 , and accordingly, the first flow rule is a predetermined time from the point in time when the connection with the SDN controller server 100 is cut off. After (Timeout), it is deleted from the network device 200 .

The reason that the first flow rule is deleted in this way is because the first flow rule has a higher priority than the second flow rule. If the first flow rule is not deleted in the network device 200 in a state in which the connection between the SDN controller server 100 and the network device 200 is disconnected, the first flow rule continues to take precedence over the second flow rule Because it is applied, the network device 200 becomes unable to process the packet. Therefore, when the connection between the network equipment 200 and the SDN controller server 100 is cut off, the first flow rule times out and is deleted.

In this case, as the first flow rule is deleted after a predetermined time elapses, the network device 200 may check whether the connection with the SDN controller server 100 is cut through whether the second flow rule is applied.

As described above, the second flow rule is set to have a lower priority than the first flow rule. To this end, the SDN controller server 100 receives and stores the second flow rule while the packet is being processed through the first flow rule in the network device 200, so that the lowest priority included in the first flow rule is A flow entry having the highest priority may be changed to have a higher priority than a flow entry having the highest priority included in the second flow rule.

Through such a series of processes, an embodiment of the present invention can operate in a headless mode that provides the same service to the host 300 even when the SDN controller server 100 is down.

That is, in an embodiment of the present invention, in a normal connection state between the SDN controller server 100 and the network equipment 200, packets are transmitted and received through the first flow rule so that all hosts 300 can communicate normally.

On the other hand, failures and issues such as inability to service a newly connected host when connection is disconnected, inability to service when an existing host is moved, and increase in flow table inefficiency due to existing policies for registered or deleted hosts remain will occur

Therefore, in an embodiment of the present invention, when the connection with the SDN controller server 100 is cut off, the first flow rule is deleted, and then packets are transmitted/received through the second flow rule, whereby the host 300 may continue to use the service being used through the corresponding network.

5 is a diagram for explaining an example in an embodiment of the present invention.

The topology in the SDN environment according to the example of FIG. 5 includes an SDN controller server, network devices 200a and 200b having a spine-leaf structure, and a host 300 connected to the network device 200 .

As an example, as the second network switch 200b-2 of the network equipment 200 is connected to the SDN controller server 100, it receives the first flow rule and the second flow rule as shown in Table 1 below, 1 Processes a packet based on a flow rule.

At this time, the second flow rule transmitted by the SDN controller server 100 is recorded in the form of a file on the disk on the internal memory of the second network switch 200b-2.

Meanwhile, a timeout (network downtime) is set in each flow entry of the first flow rule, and has a higher priority than the second flow rule.

[Table 1]

Thereafter, the second network switch 200b - 2 processes the packet based on the second flow rule as it is confirmed that the connection with the SDN controller server 100 is cut off. At this time, the existing first flow rule stored in the second network switch 200b-2 is deleted according to the timeout, and accordingly, the second network switch 200b-2 is based on the second flow rule whose priority is adjusted. to process the packet. The modified flow table is shown in Table 2.

[Table 2]

Thereafter, the second network switch 200b - 2 re-receives the first flow rule as it is reconnected with the SDN controller server 100 during packet processing based on the second flow rule. And according to the priority, the first flow rule is applied instead of the second flow rule, and the packet is processed based on the re-received first flow rule. Meanwhile, in the above description, steps S110 to S150 are the implementations of the present invention. Depending on the example, it may be further divided into additional steps or combined into fewer steps. In addition, some steps may be omitted if necessary, and the order between steps may be changed. In addition, the contents of the processing method in the network equipment when an SDN controller server failure of FIGS. 1 to 5 occurs even if other contents are omitted may be applied to the contents of FIG. 6 to be described later.

Hereinafter, a network device 200 (hereinafter referred to as a network device) that handles an SDN controller server failure in a software-defined network environment according to an embodiment of the present invention will be described.

6 is a diagram for explaining the network equipment 200 according to an embodiment of the present invention.

Referring to FIG. 6 , the network device 200 according to an embodiment of the present invention includes a communication module 210 , a memory 220 , and a processor 230 .

The communication module 210 is connected to at least one host 300 and the SDN controller server 100 to transmit and receive packets.

The memory 220 stores a program for processing a packet by applying any one of the first and second flow rules according to whether a failure occurs in the SDN-based network environment.

As the processor 230 executes the program stored in the memory 220, the first flow rule is received and applied from the SDN controller server 100 through the communication module in a state in which the connection with the SDN controller server 100 is normal. to process the packet, periodically receive and store a second flow rule different from the first flow rule from the SDN controller server 100, and when the connection with the SDN controller server 100 is cut off, based on the second flow rule process the packet.

The network equipment 200 described with reference to FIG. 6 may be provided as a component of the above-described server.

The above-described SDN controller server failure handling method according to an embodiment of the present invention may be implemented as a program (or application) and stored in a medium to be executed in combination with a computer, which is hardware.

The above-mentioned program, in order for the computer to read the program and execute the methods implemented as a program, C, C++, JAVA, Ruby, which the processor (CPU) of the computer can read through the device interface of the computer; It may include code coded in a computer language such as machine language. Such code may include functional code related to a function defining functions necessary for executing the methods, etc., and includes an execution procedure related control code necessary for the processor of the computer to execute the functions according to a predetermined procedure. can do. In addition, this code may further include additional information necessary for the processor of the computer to execute the functions or code related to memory reference for which location (address address) in the internal or external memory of the computer should be referenced. have. In addition, when the processor of the computer needs to communicate with any other computer or server located remotely in order to execute the functions, the code uses the communication module of the computer to determine how to communicate with any other computer or server remotely. It may further include a communication-related code for whether to communicate and what information or media to transmit and receive during communication.

The storage medium is not a medium that stores data for a short moment, such as a register, a cache, a memory, etc., but a medium that stores data semi-permanently and can be read by a device. Specifically, examples of the storage medium include, but are not limited to, ROM, RAM, CD-ROM, magnetic tape, floppy disk, and an optical data storage device. That is, the program may be stored in various recording media on various servers accessible by the computer or in various recording media on the computer of the user. In addition, the medium may be distributed in a computer system connected to a network, and a computer-readable code may be stored in a distributed manner.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

100: SDN controller server
200: network equipment
210: communication module
220: memory
230: processor
300: host

Claims (8)

In the case of an SDN controller server failure in a software-defined network environment, a processing method in a network device, the method comprising:
receiving, by a plurality of network devices connected to the SDN controller server, a first flow rule from the SDN controller server;
processing a packet based on the first flow rule in a state in which the connection to the SDN controller server is normal;
periodically receiving and storing a second flow rule different from the first flow rule from the SDN controller server;
checking whether at least one network device among the plurality of network devices is disconnected from the SDN controller server; and
When the connection is disconnected as a result of the check, processing a packet for a service of a host based on the second flow rule in a state in which the connection is disconnected from the SDN controller;
The plurality of network equipment processes a packet based on any one of the first flow rule and the second flow rule,
The first flow rule has a higher priority than the second flow rule in a state in which the plurality of network devices have a normal connection to the SDN controller server,
As the second flow rule is received and stored, the flow entry having the lowest priority included in the first flow rule is changed to have a higher priority than the flow entry having the highest priority included in the second flow rule become,
The step of checking whether the connection with the SDN controller server is disconnected in at least one network device among the plurality of network devices includes:
After a predetermined time has elapsed and the first flow rule is deleted, whether the connection with the SDN controller server is disconnected is checked through whether the second flow rule is applied or not,
How to deal with SDN controller server failures in software-defined network environments in network devices.
delete delete According to claim 1,
The step of periodically receiving and storing a second flow rule different from the first flow rule from the SDN controller server comprises:
As the SDN controller server periodically updates the second flow rule, the plurality of network devices periodically receive the updated second flow rule and separately on an internal memory different from the area in which the first flow rule is stored. to save,
In the event of an SDN controller server failure in a software-defined network environment, the network device handles it.
According to claim 1,
The first flow rule will be deleted from the network equipment after a predetermined period of time has elapsed from the point in time when the connection with the SDN controller server is cut off,
In the event of an SDN controller server failure in a software-defined network environment, the network device handles it.
delete According to claim 1,
receiving, by the network equipment, a first flow rule from the SDN controller server during packet processing based on the second flow rule;
applying the first flow rule in place of the second flow rule; and
Further comprising the step of processing the packet based on the re-received first flow rule,
How to handle an SDN controller server failure in a software-defined network environment.
In the case of SDN controller server failure in a software-defined network environment, in the network equipment for handling it,
A communication module for transmitting and receiving packets to and from at least one host and SDN controller server;
A memory in which a program for processing packets by applying any one of the first and second flow rules according to the occurrence of a failure in the SDN-based network environment is stored;
A processor for executing the program stored in the memory;
When the processor executes the program, the processor receives and applies a first flow rule from the SDN controller server through the communication module in a state in which the connection to the SDN controller server is normal, and processes the packet;
Periodically receive and store a second flow rule different from the first flow rule from the SDN controller server through the communication module, and when the connection with the SDN controller server is cut off, the second flow rule is disconnected from the SDN controller server Processes a packet for a service of the host based on the flow rule,
The first flow rule has a higher priority than the second flow rule in a state in which the plurality of network devices have a normal connection to the SDN controller server,
As the second flow rule is received and stored, the flow entry having the lowest priority included in the first flow rule is changed to have a higher priority than the flow entry having the highest priority included in the second flow rule become,
After a predetermined time elapses and the first flow rule is deleted, the processor determines whether the connection with the SDN controller server is disconnected through whether the second flow rule is applied.
Network equipment that handles SDN controller server failures in a software-defined network environment.

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