KR20150051107A - Method for fast flow path setup and failure recovery - Google Patents

Abstract

Disclosed is a method of fast path configuration and fault recovery in a software-defined networking environment. A software-defined networking controller can be configured to determine the path of flow from a first host to a second host and to transmit information on the path of flow to a first networking device on the path of flow. Meanwhile, the networking device can be configured to receive a packet from a preceding networking device on the path and to add a flow entry to a flow table, which is managed by the networking device, by referring to path information of the flow included in the packet. Also, the networking device can be configured to update the path information of the flow by removing items corresponding to the networking device from the path information of the flow included in the packet and transmit, to the next networking device on the path, the packet including the updated path information of the flow.

Description

[0001] The present invention relates to a fast path setup and failure recovery method,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a quick path setting and a fault recovery method, and more particularly, to a rapid path setting and a fault recovery method using a software defined network technology.

In a Software Defined Networking (SDN) environment, network devices (e.g., switches) in a network simply perform the function of delivering a received packet as specified in a flow table, The function of the control plane, such as routing for routing to the path, is performed by the SDN controller (SDN controller).

When a packet whose path is not set enters the SDN network, the entry switch that first received the packet requests the SDN controller to process the packet.

For example, open flow (OpenFlow) sends a packet_in message containing header information to inform. The SDN controller extracts flow information from the packet processing request message and calculates the route of the flow according to the policy, and adds flow entries to the switches on the route so that the packets can be transmitted through the designated route .

For example, in the case of an open flow, a flow entry consists of a match, a priority, a counter, an instruction, a timeout, and a cookie. When the switch receives a packet in the flow entry, it compares the packet header information with the match field (source and destination IP address, destination and destination MAC address, protocol, and VLAN ID) If it matches, it performs the actions specified in the instruction. The action used for generic packet transmission is an output action that forwards the packet to the designated output port, which specifies the port number to forward the packet to the desired path.

However, in the SDN environment, since the controller centrally controls path setting and failover, there is a disadvantage that the time required for path setting and failback is prolonged.

In order to solve the above problems, an object of the present invention is to provide a method of quickly establishing a path in an SDN environment.

It is another object of the present invention to solve the above problems and provide a method for quickly recovering a failure when a failure occurs on a path in an SDN environment.

According to an aspect of the present invention, there is provided a method of operating a software defined networking controller, comprising: determining a path of a flow from a first host to a second host; To a first network device on the path. ≪ Desc / Clms Page number 2 >

Here, the information on the path of the flow may include information on output ports of network devices sequentially passed from the first host to the second host.

Wherein forwarding information about the path of the flow to the first network device on the path of the flow further comprises the step of the software defined networking controller adding information about the path of the flow to the flow entry of the first network device . ≪ / RTI >

The method may further include receiving information on a packet to be transmitted from the first host to the second host, wherein the information on the packet includes a predetermined message including header information of the packet, Lt; / RTI >

Here, the information on the route of the flow may be included in a header of a packet transmitted between network devices on the route of the flow.

Here, the information on the path of the flow may be encoded and included in a header of a packet transmitted between network devices on the path of the flow.

According to another aspect of the present invention, there is provided a method of operating a network device corresponding to a software defined networking controller, the method comprising: receiving path information of a flow from the software defined networking controller; And updating the route information of the flow by removing an item corresponding to the route information of the flow and transmitting the packet of the flow including the updated route information of the flow to the next network device on the route A method of setting up a flow of a network device is provided.

Here, the path information of the flow can be received included in a flow entry added by the software defined networking controller.

Here, the information on the path of the flow may include information on output ports of network devices sequentially passed through the path.

Here, the updated information on the route of the flow may be included in the header of the packet of the flow and transmitted to the next network device on the route. At this time, when the packet is an IP (Internet Protocol) packet, information on the route of the flow may be stored in the IP options field of the packet.

According to another aspect of the present invention, there is provided a method of operating a network device corresponding to a software defined networking controller, comprising: receiving a packet from a previous network device on a path; Adding a flow entry to a flow table managed by the node, referring to the route information of the flow, updating the route information of the flow by removing an item corresponding to the route information of the flow included in the packet, And sending the packet including information to the next network device on the path.

Here, the information on the path of the flow may include information on output ports of network devices sequentially passed through the path.

Here, information on the route of the flow may be included in the header of the packet. At this time, when the packet is an IP (Internet Protocol) packet, information on the route of the flow may be stored in the IP options field of the packet.

From here. Information about the path of the flow may be encoded and included in the header of the packet.

According to another aspect of the present invention, there is provided a method of operating a software defined networking controller, the method comprising: providing a working path of a flow from a first host to a second host, The method of claim 1, further comprising: determining a backup path; performing routing for network devices present on the operational path based on the determined operational path; and providing information about the alternate path to the first To a first network device in the network.

Here, the information on the alternative path may include information on output ports of network devices sequentially passed from the first host to the second host.

Wherein forwarding information about the alternate route to the first network device on the path of the flow comprises: adding the information about the alternate route to the flow entry of the first network device by the software defined networking controller ≪ / RTI >

Here, the information on the alternative route may be included in the header of the packet transmitted between the network devices on the alternative route. At this time, if the packet is an IP (Internet Protocol) packet, information on the alternative path may be stored in the IP options field of the packet.

Here, the information on the alternative route may be encoded and included in a header of a packet transmitted between network devices on the alternative route.

Using source routing, the flow is established between the controller and the switch through fewer communications than the conventional method, allowing flow setup faster than conventional methods.

By applying the proposed method for failover, alternative paths can be set in advance, and failover can be restored faster than the existing method even if the alternative path is not set in advance.

When the fault recovery method according to the present invention is used, it is possible to reduce the controller load in order to prevent a fault or when a fault occurs.

FIGS. 1A and 1B are conceptual diagrams for explaining a flow setup method of a software defined network according to an embodiment of the present invention, in comparison with a conventional method.
2 is a conceptual diagram for explaining an example of a method of encoding flow path information in a flow setup method of a software defined network according to an embodiment of the present invention.
3 is a message flow diagram illustrating a flow setup method according to an embodiment of the present invention.
4 is a flowchart illustrating an operation method of an SDN controller for performing a flow setup method according to an embodiment of the present invention.
5 is a flowchart illustrating a method of operating a network device for performing a flow setup method according to an embodiment of the present invention.
6 is a conceptual diagram illustrating a fast failover method according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, the Unified SDN Controller referred to in the present invention means a functional entity that controls related components (e.g., switches, routers, etc.) to control the flow of traffic. The present invention is not limited to the embodiment or implementation position. For example, the integrated SDN controller may include a controller function element defined by ONF (OpenFlow), Internet Engineering Task Force (IETF), European Telecommunication Standards Institute (ETSI), and / or International Telecommunication Union Telecommunication (ITU-T) entity. The term 'switch' or 'router' referred to in the present invention means a functional element for substantially forwarding, switching, or routing traffic (or packet). The ONF, the IETF, the ETSI and / A router, a switching element, a routing element, and a forwarding element defined in ITU-T and the like.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Since the general flow setup method in the SDN environment requires adding a flow entry to all the switches located on the route to be used by the controller every time a new packet is set up, Lt; / RTI > That is, the initialization time of communication between the hosts becomes longer.

In addition, adding a flow table takes place in the central controller, which increases communication with controllers and switches, which increases the load on the centralized controller.

For example, assuming that the length of the path is n and the time it takes for the controller to send the flow entry to the switch is t, it takes a total of (1 + n) * t to set one path.

In the SDN environment, a common failure recovery method is to bypass the flows affected by the failure one by one in the event of a failure of a switch or a link. The entire process is handled by the controller, which increases the failure recovery time and increases the load on the controller.

For example, assuming that the number of flows to be bypassed is k, the average length of the bypass path of each flow is n, and the time when the controller transmits the flow entry to the switch is t, It takes time t * n.

The fast path setup and failure recovery method in the SDN according to an embodiment of the present invention provides a quick flow setup method and a failure recovery method in order to solve the problem as described above.

FIGS. 1A and 1B are conceptual diagrams for explaining a flow setup method of a software defined network according to an embodiment of the present invention, in comparison with a conventional method.

That is, FIG. 1A is a conceptual diagram for explaining a flow setup method in an existing SDN. FIG. 1B is a conceptual diagram for explaining a flow setup method in the SDN according to the present invention in the same network configuration as FIG. 1A.

In the flow setup method according to the present invention, unlike the conventional SDN flow setup method in which a flow controller adds flow entries to all switches on a path in a central controller when a new packet enters the network, The packet can be transmitted to the received entry switch, and the path can be established through a smaller number of communications than the conventional method regardless of the length of the path.

To do this, it needs a function to read the path information from the switch, add the information to the flow entry, and add the path information to the header of the packet.

First, referring to FIG. 1A, a first host 110 sends packet A 100 to a network 130 for communication with a second host 120. At this time, the packet A (100) is a new packet whose path is not set in the network 130.

The first switch 131 (hereinafter referred to as an entry switch) receiving the packet A transmitted from the first host first transmits the header information of the packet to a predetermined message 141 (for example, a packet_in message) And sends it to the SDN controller 150. At this time, the message may be a message according to an Open Flow (OpenFlow) standardization in the ONF or an Interface to Routing System (I2RS) standardized by the Internet Engineering Task Force (IETF).

The SDN controller 150 looks up the flow information of the received packet and extracts the path through which the packet is delivered according to the specified rule. For example, it is assumed that the path extracted by the SDN controller is the first switch 131, the second switch 132, and the fourth switch 134.

The SDN controller 150 sequentially specifies to the switches (the first switch 131, the second switch 132, and the fourth switch 134) on the path the port information to which the packets of the flow belonging to the packet belong (142, 143, 144).

When flow entries are added to all switches on the path, the packet is forwarded to the second host according to the set path. Thereafter, packets belonging to the flow can be transferred from the first host to the second host according to the set path.

On the other hand, referring to FIG. 1B, a flow setup method in the SDN according to the present invention can be performed as follows.

First, the first host 110 sends packet A 100 to the network 130 for communication with the second host 120. At this time, the packet A (100) is a new packet whose path is not set in the network 130.

1A, the first switch 131 (entry switch), which firstly receives the packet A 100 transmitted by the first host 110, transmits the header information of the packet to a predetermined message (for example, packet_in Message to the SDN controller 150 (161).

At this time, the message may be a message according to an Open Flow (OpenFlow) standardization in the ONF or an Interface to Routing System (I2RS) standardized by the Internet Engineering Task Force (IETF).

The SDN controller also looks at the flow information of the packet and extracts the path through which the packet is delivered according to the specified rule, as in the case described in FIG. 1A. Here, as in the case of FIG. 1A, it is assumed that the path extracted by the SDN controller is the first switch 131, the second switch 132, and the fourth switch 134.

In the conventional method described with reference to FIG. 1A, the SDN controller 150 has to perform an operation of adding, to all the switches on the path, a flow entry that sequentially specifies output port information to which packets of a flow belonging to the corresponding packet should be forwarded do.

However, in the flow setup method according to the present invention, the SDN controller 150 transmits only the information 162 about the entire flow path from the first host 110 to the second host 120 to only the first switch 131 .

That is, the SDN controller may add a flow entry containing information about the entire flow path calculated to the entry switch (first switch) that previously sent the message (e.g., the packet_in message). Here, the calculated information on the entire flow path may be encoded in a predetermined manner and added to the flow entry.

The first switch adds the path information included in the flow entry to the header of the packet and forwards the packet to the output port designated in the flow entry (163). For example, if the path for the flow is determined to be the first switch 131, the second switch 132, and the fourth switch 134 as described above, then the first switch is connected to the output port Is an output port connected to the second switch.

Next, the second switch receiving the packet checks the header information of the packet received by the source routing method. If there is path information in the header, the second switch reads the information, adds the flow entry, 134 (164).

Then, the switches (the second switch and the fourth switch) on the path repeat the process described above until a packet arrives at the second host 120. [ Finally, the flow is forwarded to the second host 220 at the same time as the flow entry is added to all the switches on the path. Thereafter, packets belonging to the flow can be transferred from the first host to the second host according to the set path.

An example of the manner in which information on the above-described flow path is inserted on the flow entry can be configured as shown in FIG.

2 is a conceptual diagram for explaining an example of a method of encoding flow path information in a flow setup method of a software defined network according to an embodiment of the present invention.

Referring to FIG. 2, by way of example, flow path information may be stored using a metadata field of an OpenFlow flow entry. However, the flow path information may be stored using a certain field on the flow entry, so long as the use is not duplicated.

By way of example, the metadata field can be composed of 64 bits and is a field configured to store meta information of flows.

First, the flag (Flag) 210 can be composed of 4 bits and can express 16 different information. In an embodiment of the present invention, it is assumed that the flag '0000' defines source routing disabled (disabled) and the flag '0001' defines source routing enabled (enabled). You can add flag values from '0010' to '1111' as needed later.

Next, information on the flow path is sequentially transmitted to the switch on the path, and a part to be referred to by each switch is the output port designation information 220 of the switch. For example, we used six bits to represent up to 64 output ports. In addition, the maximum length of the flow path is 10 nodes 220-1, ..., 220-10.

However, the field or bit values are not limited to the contents shown in FIG. 2, and the field can be adjusted according to the requirements of the network manager.

3 is a message flow diagram illustrating a flow setup method according to an embodiment of the present invention.

When the first switch 131 receives a new packet that does not exist in its own flow table, it sends a packet_in message to the controller 150 according to an open flow protocol, for example, (S310).

The controller 150 checks the flow information of the packet and calculates the path of the packet through the path first switch 131, the second switch 132 and the fourth switch 134, Information on the entire flow path is inserted into the flow entry (S320).

For example, the output port of the first switch for outputting a packet from the first switch 131 to the second switch 132 is 1, and the output port for outputting the packet from the second switch to the third switch 132 is 1, When the output port of the switch is 3 and the output port of the third switch for outputting packets from the third switch to the second host is 2, the flow path information is added to the flow entry as follows (see Fig. 2 If the encoding method described above is applied). The output port 1 for the first switch to forward the packet to the second switch is added to the flow entry according to the conventional scheme.

| 0001 0000 | 0000 0000 | 0000 0000 | 0000 0000 | 0000 0000 | 1000 0011 |

The first switch 131 confirms that the source routing is activated since the flag of the meta data field of the flow entry is '0001', and stores the flow path information added to the flow entry in the packet header, (I.e., the second switch) (S330).

At this time, in the case of the IP packet, the flow path information can use the IP options field of the header of the IP and use another field or define a new field.

The second switch 132 receives the packet to which the flow path information is added in the header from the first switch, confirms the flag value of the flow path field as in the first switch, and confirms that it is set to '0001' .

The second switch 132 reads the last six bits ('000011'; 220-10) of the output port designation portion 220 and outputs an output port for outputting a packet to the fourth switch, which is the next switch on the flow path, Recognizes that the output port 3 is the output port 3, adds a flow entry for designating the output port 3, and outputs the packet to the fourth switch (S340). At this time, the second switch removes the content of the flow path (the last six bits '000011'; 220-10) consumed by the second switch, and transmits the remaining contents to the fourth switch.

At this time, a 6-bit right shift operation or the like can be used as a method for removing the contents (the last 6 bits '000011') of the flow path consumed by the second switch.

Similarly, the fourth switch 134 receives the flow path information excluding the path information consumed by the second switch 132 from the second switch 132. For example, the flow path information received by the fourth switch may be configured as follows.

| 0001 0000 | 0000 0000 | 0000 0000 | 0000 0000 | 0000 0000 0000 0010 |

The fourth switch recognizes that the source routing is activated by checking the flag ('0001'), and the flow of designating the output port 2 indicated by the last 6 bits (the value of 220-9 by 6-bit right shift operation in FIG. 2) Adds the entry, and outputs the packet to the output port 2 (S350).

In the above embodiment, an example has been described in which information on a path of a flow is stored using output ports of network devices sequentially passing through. However, the information about the path of the flow may not be an output port that should be selected in each network device on the path, but may be designated as a unique identifier that can specify the next network device in each network device.

The flow setup method using the SDN technique according to the present invention described with reference to FIG. 2 and FIG. 3 will be described below with reference to the view of the SDN controller and the view of the network device managed by the SDN controller, respectively.

4 is a flowchart illustrating an operation method of an SDN controller for performing a flow setup method according to an embodiment of the present invention.

Referring to FIG. 4, an SDN controller for performing a flow setup method according to an embodiment of the present invention includes a step S420 of determining a path of a flow from a first host to a second host (S420) (S430) of forwarding the information to the first network device on the path of the flow.

In addition, the SDN controller may further include receiving (S410) information on a packet to be transmitted to the second host from the first network device, and the information on the packet includes header information of the packet May be received in the form of a predetermined message (e.g., packet_in) included.

At this time, in the case where a packet that has flown into the first host is a packet that is first introduced into the network, information about the packet is transmitted to the SDN controller.

The SDN controller knows the topology and link costs of all the network devices existing in the network due to the characteristics of the SDN technology, and thus can calculate the optimal path of the flow from the first host to the second host.

The information on the path of the calculated flow sequentially includes information on the output ports of the network devices existing on the path from the first host to the second host. Information on the path of the flow can be encoded and stored in a predetermined field in the flow entry of the first network device (first switch) on the flow path by the SDN controller. One embodiment of this may be the method illustrated in FIG.

Also, the information on the route of the flow may be included in the header of a packet transmitted between network devices existing on the route of the flow, and may be transmitted in a source routing manner.

Information on the flow path that is included in the header of the packet in the source routing manner can be used for flow setup in each network device.

5 is a flowchart illustrating a method of operating a network device for performing a flow setup method according to an embodiment of the present invention.

5, a method of operating a network device for performing a flow setup method according to an exemplary embodiment of the present invention includes receiving a packet from a previous network device on a path (S510), determining a path of a flow included in the packet (S520) of adding a flow entry to the flow table managed by the node by referring to the information, and updating the path information of the flow by removing an item corresponding to the flow information of the flow included in the packet, And transmitting the packet including path information of the flow to a next network device on the path (S530).

As described with reference to FIG. 4, the path information of the flow included in the packet sequentially includes information on the output ports of the network devices existing on the path from itself to the final destination (i.e., the second host) do.

For example, in the case illustrated in FIG. 1B, the second switch receives the output port information from itself to the fourth switch and the path information of the flow including the output port information from the fourth switch to the second host. In the same case, the fourth switch receives the path information of the flow including the output port information from itself to the second host.

Meanwhile, the flow setup method in the SDN according to the present invention can also be used for fast failure recovery.

6 is a conceptual diagram illustrating a fast failover method according to an embodiment of the present invention.

That is, the fast failure recovery method illustrated in FIG. 6 is a method of performing a quick recovery using the flow setup method described above when a failure occurs in a link on a set flow path.

In the conventional path protection method, since the backup path is set at the same time during the flow setup, there is a difficulty that the switch manages the flow table in a double manner, and the load on the controller also increases.

On the other hand, the fast failure recovery method according to an embodiment of the present invention does not need to additionally manage and add a flow entry because the backup path is encoded and inserted into a flow entry of one switch, not all switches on the backup path. Can be reduced.

The first switch (entry switch) 131, which first receives a packet when a new packet enters the network, sends a predefined message (e.g., a packet_in message) to the controller 150 as shown in FIGS. 1A and 1B. To inquire about the processing.

At this time, the controller 150 calculates two paths, a working path and a backup path, and finds a path to be bypassed when a failure occurs. In the case of the operation path, the path can be set (172, 173, 174) as in the conventional method, and the alternative path is encoded in the metadata field of the flow entry using the encoding method of the flow path information described above with reference to FIG. (175).

Hereinafter, the first switch 131, the second switch 132, and the fourth switch 134 are set as an operation path, and the first switch 131, the third switch 133, A fast failover method according to the present invention when switch 134 is set as an alternative path is described.

For example, it is assumed that a failure 180 occurs on a link connecting the first switch 131 and the second switch 132.

Typically, the first switch 131 looks up the header of an incoming packet, finds a flow entry matching the match field in the flow table, and searches for action lists. The fast failure recovery method according to the present invention can use a fast failover type group entry provided in Open Flow 1.3 as an example.

If the action is set as a group, the group table is searched to extract a corresponding group entry, and a port to sequentially transmit a packet is retrieved from the action list. If an output port having a high priority (i.e., (I.e., the output port from the first switch to the third switch) when a failure occurs in the output port of the first switch (i.e., the output port of the first switch). When a packet is transmitted to the next priority port due to a failure, the encoded path information is checked. If the source routing of the flag field is activated, the packet can be inserted into the header of the packet and sent to the designated port.

That is, when the first switch detects that a failure has occurred in the link between the first switch and the second switch, the first switch refers to the fast-failover field of the group entry and notifies the alternate- (The first switch - > the third switch - > the fourth switch) by referring to the information about the path.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

110: first host 120: second host
131 ~ 134: Network devices
150: SDN controller
200: Flow path information 210: Flag
220: About output port specification

Claims (19)

A method of operating a software defined networking controller,
Determining a path of a flow from a first host to a second host; And
And forwarding information about the path of the flow to a first network device on the path of the flow. The method according to claim 1,
Wherein the information about the path of the flow includes information about output ports of network devices sequentially passed from the first host to the second host. The method according to claim 1,
Wherein the step of communicating information about the path of the flow to the first network device on the path of the flow further comprises the step of the software defined networking controller adding information about the path of the flow to the flow entry of the first network device Wherein the software-defined networking controller is configured to perform a flow setup of the software defined networking controller. The method according to claim 1,
Further comprising receiving information on a packet to be forwarded from the first host to the second host,
Wherein the information about the packet is received in the form of a predetermined message including header information of the packet. The method according to claim 1,
Wherein the information about the path of the flow is included in a header of a packet transmitted between network devices on the path of the flow. The method of claim 5,
Wherein the information about the path of the flow is encoded and included in a header of a packet transmitted between network devices on the path of the flow. A method of operating a network device corresponding to a software defined networking controller,
Receiving path information of a flow from the software defined networking controller; And
Updating the route information of the flow by removing an item corresponding to the route information of the flow, and transmitting the packet of the flow including the updated route information of the flow to the next network device on the route , A method of setting up a flow of a network device. The method of claim 7,
Wherein the path information of the flow is included in a flow entry added by the software defined networking controller. The method of claim 7,
Wherein the information about the path of the flow includes information about output ports of network devices sequentially passed on the path. The method of claim 7,
Wherein the updated information of the route of the flow is included in the header of the packet of the flow and is transmitted to the next network device on the route. A method of operating a network device corresponding to a software defined networking controller,
Receiving a packet from a previous network device on the path;
Adding a flow entry to a flow table managed by itself by referring to path information of a flow included in the packet; And
Updating the route information of the flow by removing an item corresponding to the route from the flow information of the flow included in the packet and transmitting the packet including the updated route information of the flow to the next network device on the route ≪ / RTI > The method of claim 11,
Wherein the information about the path of the flow includes information about output ports of network devices sequentially passed on the path. The method of claim 11,
And the information on the path of the flow is included in the header of the packet. 14. The method of claim 13,
Wherein the information about the path of the flow is encoded and included in a header of the packet. A method of operating a software defined networking controller,
Determining a working path of a flow from a first host to a second host and a backup path to be used when a failure occurs on the operating path;
Performing path setting for network devices existing on the operation path based on the determined operation path; And
And forwarding information about the alternate path to the first network device on the path of the flow. 16. The method of claim 15,
Wherein the information about the alternate path includes information about output ports of network devices sequentially passed from the first host to the second host. 16. The method of claim 15,
Wherein forwarding the information about the alternative route to the first network device on the path of the flow is performed by adding the information about the alternative route to the flow entry of the first network device by the software defined networking controller Wherein the software-defined networking controller is a fast failover method. 16. The method of claim 15,
Wherein the information on the alternative path is included in a header of a packet transmitted between network devices on the alternative path. 16. The method of claim 15,
Wherein the information on the alternate path is encoded and included in a header of a packet transmitted between network devices on the alternate path.

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