KR20140039014A - Switch migration method for software-defined-networks with a plurality of controllers - Google Patents

Abstract

The prevent invention relates to a software defined network (SDN), providing a switch migration method for a SDN which is capable of recognizing that the switch migration mode has been changed from the openflow switch migration in which one of multiple slave controllers connected to a network switch enters the master mode towards another openflow switch migration in which the master mode controller to which packets are inputted by the switch enters the slave mode as well as providing the switch migration process with no packet being lost.

Description

[0001] The present invention relates to a method for changing a switch connection in a software defined network having a plurality of controllers,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a software defined network (SDN), in which switching flows of an openflow standard for switching one of the controllers of the slave mode to the master mode in an environment where a plurality of controllers are connected to the network switch, And more particularly to a method of changing a switch connection in a software defined network having a plurality of controllers providing the same.

Recently, explosive increase of wireless data due to increase in demand and usage of smartphone, convergence of broadcasting and communication industries such as cloud computing, M2M and smart TV, and convergence industry centering on ICT have demanded advancement of network technology. Accordingly, a technology developed as a technical alternative to overcome the limitations of the network structure and to accommodate new requirements is a software defined network (SDN). Software-defined networks provide networking flexibility and effective management capabilities by transforming network configurations from fixed hardware to software-based ones to accommodate changes in the environment of communication service providers and enterprises.

As a background to the present invention, there is a software defined networking support technique that provides application layer optimization of WO 2013/139298 Al, shown in FIG. This technology is a network node that manages control plane functions for a plurality of nodes in a Software Defined Network (SDN) domain, collects a plurality of network information from each node and forwards the network information based on rules determined for each domain And a processor for receiving traffic optimization information according to the network information, and performing a forwarding determination operation for each node based on the traffic optimization information. In yet another embodiment, the method may include collecting primary network information from one or more software defined network (SDN) nodes, collecting network information received from software defined network (SDN) nodes, And an application layer traffic optimization (ALTO) node including a processor for performing a plurality of traffic optimization decisions to forward traffic optimization determination results to software defined network (SDN) nodes.

Another background to the present invention is a system and methodology for providing a branch data plane in a transmission based switching device as shown in FIG. 2. The technique features a network switching device having a hardware data plane including a macro flow subplane for performing packet based routing of a network switching device and a microflow subplane for performing transmission based routing of the network switching device. The network switching device receives packet-based routing rules from a software defined network (SDN) controller and provides transmission-based routing rules to the microflow subplane.

As another background of the present invention, there is a software defined network (SDN) controller technology in which the route classification and prioritization function shown in FIG. 3 is programmed and a switch routing table is used. The technology includes a software defined network (SDN) controller coupled to one or more switches in the network, one or more devices connected to the one or more switches and one or more switches, SDN) controller having integrated logic performed by a processor, wherein the integration logic determines an SDN route between the one or more plurality of devices and each of one or more of the plurality of switches to provide to a software defined network (SDN) controller .

WO 2013139298 A1 US 20130223226 A1 US 20130266007 A1 US 20130215215 A1 WO 2013104375 A1 KR 10-2012-0016285 A KR 10-1044835 B1

 'OpenFlow Switch Specification', Version 1.3.3 (Protocol version 0x04), Open Networking Foundation, September 27, 2013  'SDN Architecture Overview', Version 1.0, Open Networking Foundation, December 12, 2013   'Software-Defined Networking: The New Norm for Networks', ONF White Paper, Open Networking Foundation, April 13, 2012

In an environment where multiple controllers are connected to a network switch, switch migration of the openflow standard that changes one of the controllers of the slave mode to master mode determines whether or not the master mode is changed between the controller and the switch However, there is a problem that the controller which is in the master mode as an initial state is not provided with a configuration that recognizes that the mode is changed to the slave mode. As a result, the controller, which was in the master mode, transmits a packet to the switch side (packet-out) after the propagation delay and the processing delay required for each node to process the packet, A packet from the controller is regarded as a controller-to-switch message, and the packet loss is inevitable.

SUMMARY OF THE INVENTION The present invention provides a method for changing a switch connection in a software defined network having a plurality of controllers capable of recognizing that a controller that was in the master mode as an initial state in switch migration of the openflow standard is changed to the slave mode .

Another object of the present invention is to provide a switch connection changing method in a software defined network having a plurality of controllers that provide switch migration of an openflow standard without packet loss.

In order to solve the above problem, the present invention is not limited to a system in which a master controller in which a packet is transmitted from a switch recognizes that the controller is switched to the slave mode by switch migration of the openflow standard, It provides a way to change the switch connection in a software defined network as a solution to the problem.

According to the method for changing the switch connection in the software defined network having a plurality of controllers of the present invention, it is possible to provide a technical effect to enable the controller, which is in the master mode as the initial state in the switch migration of the openflow standard, to recognize that the controller has been changed to the slave mode .

Further, according to the switch connection changing method in the software defined network having a plurality of controllers of the present invention, it is possible to achieve an effect of enabling switching migration of the openflow standard without packet loss.

FIG. 1 is a schematic diagram of a configuration of a software-defined networking support technology that provides application layer optimization
FIG. 2 is a further background of the present invention as a system and methodology for providing a branch data plane in a transmission-based switching device.
FIG. 3 is a diagram of another configuration of a software defined network (SDN) controller technology in which a route classification and prioritization function is programmed and a switch routing table is used
Figure 4 shows the logical structure of the SDN architecture
FIG. 5 is an example of a software defined network configuration having a plurality of controllers according to the present invention;
6 shows an example of a plurality of controller configurations in a software defined network of the present invention
FIG. 7 shows a flow of a switch connection change (Migrate Switch) according to the OpenFlow switch standard of ONF (Open Networking Foundation)
FIG. 8 is a diagram illustrating a packet loss process according to a switch connection change according to an OpenFlow switch standard of ONF (Open Networking Foundation)
FIG. 9 is a flow chart of a process of changing a switch connection in a software defined network having a plurality of controllers according to the present invention;

The following merely illustrates the principles of the invention. Accordingly, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention. It is to be understood that all of the conditional terms and embodiments recited herein are expressly intended to be purely for purposes of understanding the concepts of the present invention and are not intended to be limiting to such specifically recited embodiments and conditions . It is also to be understood that the detailed description, as well as the principles, aspects and embodiments of the invention, as well as specific embodiments thereof, are intended to cover structural and functional equivalents thereof.

The above objects, features and advantages will become more apparent from the following detailed description in conjunction with the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The recent emergence of cloud services, the explosive growth of mobile devices and content, and server virtualization are emerging as major trends for new discussion on traditional traditional network architectures. Most existing networks consist of a hierarchical structure made up of an Ethernet switch layer arranged in a tree structure. In the network sector, this hierarchical design is a common design in a situation where client-server computing dominates. However, this fixed hierarchical network architecture is not suitable for the dynamic computing or storage environments required by today's large enterprise data centers and carrier environments. It is virtually impossible to meet the requirements of the current network market with traditional network architectures. As a result, the existing network architecture is not designed to meet the needs of various consumers such as today's consumers, companies, and telecom operators.

Software-defined network or software defined networking (SDN) is a network architecture in which network control functions are separated from packet forwarding and support direct programming. In the SDN, since the control area is separated and accessible to the computing device as an accessible computing device, it is possible to utilize applications and network services that can manage and control the network as a logical or virtual entity.

Figure 4 shows the logical structure of the SDN architecture, where the core functions of the network are focused on a software-based SDN controller that controls the network as a whole. Thus, the network appears as an application, such as a single logical switch. By centralizing the network to the control layer, SDN also provides flexibility in network configuration, management and security, and can optimize network resources through the SDN program. This SDN architecture enables users to customize their business objectives to meet their business objectives, including routing, multicast, security, access control, bandwidth management, traffic engineering, processor and storage optimization, quality of service, energy usage, Provides a set of APIs to implement network services. Thus, by using an open API between the SDN control and the application layer, it is not tied to details for the execution of business applications and can operate on the network utilizing network services and functions.

OpenFlow technology, a core component of SDN, has transformed traditional closed networking technologies into open networking technologies, providing the basis for developing new networking technologies. Established to promote commercialization and standardization of OpenFlow technology, ONF (Open Networking Foundation) redefined networking technology as a computing technology and defined Software-Defined Networking (SDN) technology based on OpenFlow technology.

OpenFlow can be understood as a kind of routing protocol corresponding to a standard communication interface. Therefore, OpenFlow acts as a communication between OpenFlow controller and OpenFlow-enabled network equipment (switch / router). Current IP-based routing does not allow the flow of data between two endpoints to the same path in the network, regardless of various levels of demand, and ultimately fails to provide control to the user at the application and session layer . In general, network devices (routers, switches) handle network traffic using hardware-based flow tables. However, OpenFlow technology provides programmable network equipment by manipulating the flow table through the software controller to set the data path.

FIG. 5 shows an example of a software defined network configuration having a plurality of controllers according to the present invention. The software defined network of the present invention includes a Distributed SDN Control Plane to which the physical network infrastructure and the physical network infrastructure shown in the lower part of the figure are connected. Wherein the distributed SDN control plane includes a plurality of nodes and a distributed data store for storing distributed data for the nodes, each of the nodes including a core control module to which a physical network infrastructure is connected, And applications provided to the physical network infrastructure through the core control module. The Distributed SDN Control Plane is configured as a controller that measures the load on the physical network infrastructure and calculates the balance state of the load by using Load Adaptation Decisions. The distributed SDN control plane performs a control to control a software defined network (SDN) according to the balance state of the load by the load adaptation determination unit, and performs a change of a switch connection, a removal of a controller, .

FIG. 6 shows an example of a plurality of controller configurations in a software defined network of the present invention. When there is less traffic in the Distributed SDN Control Plane, a Single Control Plane can be configured by a single controller. However, in order to prevent bottleneck due to increase of traffic, it is necessary to construct a multi-control plane by a plurality of controllers and perform distributed processing. In an environment where multiple controllers manage the SDN network, one or more controllers are connected to each switch to control each switch. At this time, the switch is operated by dividing the controllers into three modes of Equal, Master, and Slave, and the controllers are configured to exchange information with a separate channel between the controllers together with connection to the switch.

The controller in Equal mode is allowed access to the connected switch and receives all asynchronous messages from the switch. A controller in Equal mode can change the mode of a switch by sending a controller-to-switch message to the connected switch.

Master mode controllers, like Equal mode, are allowed full access to the connected switch and receive all asynchronous messages from the switch. The master mode controller can also change the mode of the switch by sending a controller-to-switch message to the connected switch. However, the difference between Equal mode and Master mode is that the Master controller must exist as a single controller for each switch.

The controller in slave mode only has read-only access to the switch. If the controller in the slave mode can not receive the asynchronous message provided by the switch and the controller transmits the controller-to-switch message for changing the state of the switch to the switch side, the switch is configured to send the error packet to the controller side. Ignore the controller-to-switch messages sent by the controller. Therefore, the controller in Slave mode uses the OFPT_ROLE_REQUEST message to change the state of the switch.

There is a condition that must be maintained in performing switch migration in an environment where the SDN network is managed by a plurality of controllers. It is a safety condition and a liveness condition.

A safety condition is that all messages from the switch must be processed by a single controller. If the messages provided by the switch are processed by more than one controller at the same time, the processing may be different and the processing information may be superimposed on the switch side, resulting in undesirable results. When a message provided by a switch performs different processing on two or more controllers and transmits different commands to the switch, commands from each controller are superimposed on the switches to give different commands to the packets belonging to the same flow . Therefore, the messages provided by the switch must be processed by a single controller. In order to maintain these safety conditions, Switch Migration using Equal mode is not suitable for checking the messages provided by the switch to the controllers in an environment where multiple controllers manage the SDN network.

Next, the liveness condition means that at least one controller for each switch should be connected in an active state. In other words, in order to satisfy the liveness condition, the switch must always have at least one master mode controller or at least one equal-mode controller in order to process the messages provided by the switch. Considering only the liveness condition, all controllers connected to the switch can be assigned to the Equal mode, but at the same time, the Master mode and the Slave mode must be used to satisfy the safety condition.

FIG. 7 shows the flow of a switch connection change (Migrate Switch) according to the OpenFlow switch standard of ONF (Open Networking Foundation). Migration means changing one of the controllers in Slave mode to Master mode in an environment where more than one controller is connected to the switch. In the drawing, the controller in the slave mode is referred to as the first controller 100 as an initial state, the controller in the master mode in the initial state is referred to as the second controller 200, and the first controller 100 and the second controller 200 are connected The switch 300 will be described as an example.

According to the Openflow standard;

- The first controller 100 in the slave mode requiring a change to the master mode requests the switch 300 to change to the master mode using the OFPT_ROLE_REQUEST message (S010).

The switch 300 receiving the OFPT_ROLE_REQUEST message changes the first controller 100 that has transmitted the OFPT_ROLE_REQUEST message to the master mode and changes the second controller 200 that was in the previous master mode to the slave mode. The switch 300 transmits a Role Reply to the first controller 100 requesting change to the Master mode using the OFPT_ROLE_REQUEST message (S020).

At this time, the switch 300 recognizes the first controller 100 as a Master controller from the time of transmitting the Role Reply indicating that the mode is changed to the Master mode to the first controller 100, and transmits the OFPT_ROLE_REQUEST message to the first controller 100 Is connected to the master controller from the time when the relay reply is received from the switch 300.

As shown in the figure, the switch between the first controller 100 and the switch 300 that requests the change to the master mode is a switch between the switch 300 and the switch 300, It is possible to distinguish whether or not the mode is changed, but there is a problem that the second controller 200, which was the master mode as an initial state, is not provided with a configuration capable of recognizing that the mode has been changed to the slave mode.

FIG. 8 is a diagram illustrating a packet loss process according to a switch connection change according to an OpenFlow switch standard of ONF (Open Networking Foundation).

When a packet is transmitted from the switch 300 to the second controller 200 in the master mode, the packet loss due to the change of the switch connection (migration switch) A processing delay occurs. This is applied to a switch connection change (Migrate Switch) according to the Openflow standard of FIG. 7 as follows.

- A packet is transmitted from the switch 300 to the second controller 200 side in the Master mode (S000)

- The first controller 100 in the slave mode requiring a change to the master mode requests the switch 300 to change to the master mode using the OFPT_ROLE_REQUEST message (S010).

The switch 300 receiving the OFPT_ROLE_REQUEST message changes the first controller 100 that has transmitted the OFPT_ROLE_REQUEST message to the master mode and changes the second controller 200 that was in the previous master mode to the slave mode. The switch 300 transmits a Role Reply to the first controller 100 requesting change to the Master mode using the OFPT_ROLE_REQUEST message (S020).

At this time, the switch 300 recognizes the first controller 100 as a Master controller from the time of transmitting the Role Reply indicating that the mode is changed to the Master mode to the first controller 100, and transmits the OFPT_ROLE_REQUEST message to the first controller 100 Is connected to the master controller from the time when the relay reply is received from the switch 300.

The second controller 200 in the master mode has been changed from the time when the switch 300 transmits the relay reply to the first controller 100 to the slave mode so that the propagation delay and each node processes the packet The packet is transmitted from the second controller 200 to the switch 300 in step S030 after a processing delay for processing the first controller 200. The switch 300 is connected to the second controller 200 as a controller-to-switch message and drops it out. Therefore, packet loss is inevitable in the above process.

FIG. 9 shows a processing flow of a switch connection changing method in a software defined network having a plurality of controllers according to the present invention.

A first controller 100 as a slave mode controller and a second controller 200 in a single master mode and wherein the first controller 100 and the second controller 200 are connected to the switch 300 Wherein the first controller (100) and the second controller (200) are connected to each other through a channel between controllers, the method comprising: Will be described in detail.

A packet is transmitted from the switch 300 to the second controller 200 in the Master mode (S100)

The second controller 200 in Master mode, which is requested to change to the slave mode, transmits a packet indicating the start of switch migration to the first controller 100 side of the slave mode through the channel between the controllers. At this time, the second controller 200 adds time stamp information to the packet indicating the start of switch migration and transmits it to the first controller 100 (S110). Thereafter, the second controller 200 in the master mode stores and stores the packet provided from the switch 300 without processing.

The first controller 100 of the slave mode which has received the packet informing the start of the switch migration from the second controller 200 in the master mode requests to the connected switch 300 side to change to the master mode by using the OFPT_ROLE_REQUEST message (S120).

The switch 300 receiving the OFPT_ROLE_REQUEST message changes the first controller 100 that has transmitted the OFPT_ROLE_REQUEST message to the master mode and changes the second controller 200 that was in the previous master mode to the slave mode. Then, the switch 300 transmits a Role Reply to the first controller 100 requesting the change to the Master mode using the OFPT_ROLE_REQUEST message (Step S130).

At this time, the switch 300 recognizes the first controller 100 as a Master controller from the time of transmitting the Role Reply indicating that the mode is changed to the Master mode to the first controller 100, and transmits the OFPT_ROLE_REQUEST message to the first controller 100 Is connected to the switch 300 as a master controller from the time of receiving the relay reply from the switch 300. [

The first controller 100 receives the relay reply from the earswitch 300 and determines that the master mode has been changed. The first controller 100 notifies the second controller 200 that the slave mode has been changed to Ready for And transmits the migration packet through the channel between the controllers (S140). The first controller 100 adds time stamp information to the Ready for Migration packet and transmits it to the second controller 200 side.

Next, the second controller 200 receiving the Ready for Migration packet transmits a 'Hello' packet to the switch 300 (S150)

- The switch 300 transmits an error message to the 'Hello' packet from the second controller 200 changed to the slave mode (S160). Therefore, the second controller 200 can determine that the master mode has been changed from the previous master mode to the slave mode.

Next, the second controller 200 changed to the slave mode transmits an End of Migration message informing that the switch migration is completed to the first controller 100 which has been changed to the master mode, (S170). At this time, the first controller 100 changed to the master mode refers to the time stamp information included in the packet indicating the start of the switch migration and the time stamp information of the Ready for Migration packet, and stores it in the second controller 200 changed to the slave mode Packet loss is prevented by processing the packet.

According to the switch connection changing method in the software defined network having the plurality of controllers of the present invention described above, the switch migration of the openflow standard is provided without packet loss.

Although the method for changing a switch connection in a software defined network having a plurality of controllers according to the present invention has been described with reference to the limited embodiments and drawings, the present invention is not limited thereto and the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: first controller 200: second controller
300: Switch

Claims (7)

A first controller 100 as a slave mode controller and a second controller 200 in a single master mode and wherein the first controller 100 and the second controller 200 are connected to the switch 300 And a plurality of controllers connected to the first controller (100) and the second controller (200) through a channel between the controllers, the method comprising:
A step S100 of transmitting a packet from the switch 300 to the second controller 200 of the master mode,
Transmitting, by the second controller 200 of the master mode requiring the change to the slave mode, a packet indicating the start of switch migration to the first controller 100 in the slave mode through a channel between the controllers (S110);
The first controller 100 of the slave mode which has received the packet informing the start of the switch migration from the second controller 200 of the master mode transmits the OFPT_ROLE_REQUEST message to the connected switch 300 side to change to the master mode (S120), < / RTI >
The switch 300 having received the OFPT_ROLE_REQUEST message changes the first controller 100 that has transmitted the OFPT_ROLE_REQUEST message to the master mode and changes the second controller 200 that was in the previous Master mode to the slave mode, The controller 300 performs a step S130 of transmitting a role reply to the first controller 100 requesting change to the master mode using the OFPT_ROLE_REQUEST message,
Then, the first controller 100 that has received the Role Reply from the switch 300 and has been changed to the master mode is ready for informing that it is ready to receive switch migration information for the second controller 200 changed to the slave mode. Transmitting a migration packet through a channel between controllers (S140),
Next, the second controller 200 receiving the Ready for Migration packet transmits a 'Hello' packet to the switch 300 (S150), and
- The switch 300 transmits an error message to the 'Hello' packet from the second controller 200 changed to the slave mode (S160)
Next, the second controller 200 changed to the slave mode transmits an End of Migration message informing that the switch migration is completed to the first controller 100 which has been changed to the master mode, (S170),
And a method for changing a switch connection in a software defined network having a plurality of controllers
2. The method of claim 1, wherein the second controller 200 of the master mode requiring the change to the slave mode transmits a packet indicating the start of switch migration to the first controller 100 in the slave mode through a channel between the controllers. (S110),
In the software defined network having a plurality of controllers, the second controller 200 further comprises the step of adding time stamp information to the packet indicating the start of the switch migration to the first controller 100 side. How to change the switch connection
The method of claim 2, wherein the second controller 200 adds time stamp information to a packet indicating the start of switch migration and transmits the time stamp information to the first controller 100 (S110).
After the second controller 200 adds time stamp information to the packet indicating the start of switch migration and transmits the packet to the first controller 100, the second controller 200 processes the packet provided from the switch 300 And storing and storing the program in a software definition network having a plurality of controllers.
The method of claim 1, wherein in the step S130 of transmitting a relay reply indicating that the switch 300 has been changed to the master mode to the first controller 100 side,
Wherein the switch (300) is configured to recognize the first controller (100) as a master controller from the time of transmitting the Role Reply.
The method of claim 1, wherein in the step S130 of transmitting a relay reply indicating that the switch 300 has been changed to the master mode to the first controller 100 side,
The first controller 100 that has transmitted the OFPT_ROLE_REQUEST message is configured to be connected to the switch 300 as a master controller from the time of receiving the relay reply from the switch 300. In a software defined network having a plurality of controllers, How to change connection
The method of claim 1, wherein the first controller 100 transmits a Ready for Migration packet through the channel between the controllers indicating that the first controller 100 is ready to receive switch migration information for the second controller 200 changed to slave mode ( S140),
The first controller 100 further includes adding time stamp information to the Ready for Migration packet and transmitting the time stamp information to the second controller 200. The switch connection is changed in a software defined network having a plurality of controllers. Way
The method according to claim 1, wherein the second controller (200) changed to the slave mode transmits an end of migration message to the first controller (100), which has been changed to the master mode, In step S170,
The first controller 100, which has received the End of Migration message and the packet stored and stored in the second controller 200 without processing the end of migration message, transmits a time stamp and a Ready for Migration packet Further comprising the step of processing the packet stored and held in the second controller (200) changed to the slave mode with reference to the time stamp information of the second controller (200).

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