KR20210016802A - Method for optimizing flow table for network service based on server-client in software defined networking environment and sdn switch thereofor - Google Patents

Abstract

Disclosed are a method for optimizing a flow policy for performing a duplicating operation generated in a flow table of a software defined networking (SDN) switch connected to a destination communication terminal as one policy when a plurality of communication terminals connected to the same SDN switch communicate with a common destination terminal connected to another SDN switch, and an SDN switch therefor. According to an embodiment of the present invention, the method for optimizing a flow table in an SDN switch, comprises the steps of: requesting an SDN controller for a flow policy, and receiving the flow policy from the SDN controller in response thereto; identifying the flow policy for performing the same operation as the received flow policy in a flow table; and maintaining a value of a matching field item matching among matching field items of the identified flow policy and the received flow policy, replacing a value of a matching field item which does not match, with a null value to redefine the same as a single flow policy, and registering the same in the flow table.

Description

How to optimize flow table for server-client based network service in software-defined networking environment, and SDN switch for it {METHOD FOR OPTIMIZING FLOW TABLE FOR NETWORK SERVICE BASED ON SERVER-CLIENT IN SOFTWARE DEFINED NETWORKING ENVIRONMENT AND SDN SWITCH THEREOFOR}

The present invention relates to a software defined networking (SDN) technology, and more specifically, to a method for optimizing a flow table of an SDN switch in an SDN environment and an SDN switch for the same.

Software Defined Networking (SDN) separates the control plane and data plane constituting the conventional network equipment, and the control plane manages, monitors, and controls the network. Networking in a centralized structure that is responsible for the overall processing related to At this time, the control plane is called'SDN controller', and the SND controller can control network equipment corresponding to the data plane through standardized control plane interfaces such as OpenFlow and NetConf. In addition, the SDN controller provides the user with the abstracted network resource information collectively collected from the connected network equipment, and based on this abstracted network resource information, it enables flexible network operation that is more optimized for performance than the existing network. For example, when a large number of packets flow into the SDN switch, the SDN controller detects it and performs load balancing, or analyzes it even if a packet containing malicious code flows into the SDN switch. Pre-blocking is possible. In addition, by creating a topology map using the connection information resources of network equipment, it provides network administrators with high visibility of the entire network, such as fast fault detection, efficient resource management and policy application. In the case of SDN controllers, various vendor solutions and open sources exist, and most SDN controllers communicate with network equipment based on the OpenFlow protocol defined by ONF (Open Networking Foundation).

In the OpenFlow standard, the SDN controller establishes a separate control channel with the SDN switch and registers the flow policies for processing data packets flowing into the SDN switch in the flow table of the SDN switch to register the traffic of the SDN switch. Control. At this time, flow policies are defined in the flow table in two ways according to the operation mode of the SDN controller. One is Re-Active method and the other is Pro-Active method. The two methods differ in the subject that determines the path of the packet. In the Re-Active method, when an inquiry about a specific packet path comes from the SDN switch, the SDN controller directly calculates the optimal path based on the topology map, and then registers the flow policy in the flow table of the SDN switch existing on the path. In the Pro-Active method, the flow policy for packets flowing into the SDN switch through the network manager or an external application is registered in the flow table of the SDN switch through the SDN controller in advance.

When registering a flow policy on an SDN switch through the Re-Active method among the above two methods, N (N≥2) source communication terminals connected to one SDN switch communicate with one destination communication terminal connected to another SDN switch. In the case of, a flow policy for performing a redundant operation is registered in the SDN switch connected to the destination communication terminal. Here, the overlapping of the flow policy means that the same flow policy is not registered as a duplicate, but that a flow policy that performs the same operation is registered as a duplicate. It will be described with reference to FIGS. 1 and 2 as follows.

FIG. 1 is a diagram illustrating an SDN-based network environment, and FIG. 2 is a diagram illustrating a flow policy registered in a second SDN switch of FIG. 1. Referring to FIG. 1, two SDN switches 120 and 130 are connected to the SDN controller 110 by establishing a control channel, and two communication terminals 121 and 122 are connected to the first SDN switch 120. And one communication terminal 131 is connected to the second SDN switch 130. When the two communication terminals 121 and 122 communicate with the one communication terminal 131, that is, the destination communication terminal 131, the flow table of the second SDN switch 130 is shown in FIG. The same flow policy is registered.

Referring to FIG. 2, flow ID bb01 and flow ID bb03 are flow policies that perform an operation of sending a packet from port 1 of the second SDN switch 130 to port 2, and the two flow policies are source MAC Only the address and the source IP address are different, and the operation performed by the second SDN switch 130 is the same. Flow ID bb02 and flow ID bbo4 are flow policies that perform an operation of sending a packet from port 2 of the second SDN switch 130 to port 1, and the two flow policies are only the destination MAC address and the destination IP address. Only different, the operation performed by the second SDN switch 130 is the same. From the perspective of the SDN controller 110, even though the operation is performed identically, some matching conditions are different, so it is recognized as a different flow policy and a unique flow ID is assigned to manage the flow policy. However, the greater the number of communication terminals connected to the same SDN switch to communicate with the common destination communication terminal, and the greater the number of SDN switches connected to the destination communication terminal, the proportionally the SDN switch connected to the destination communication terminal. In the flow table, flow policies that perform redundant operations are bound to increase. As the flow policies increase in this way, it takes a lot of time to process packets of the SDN switch, and it causes the performance of the switch itself to deteriorate. In particular, this problem may mainly occur in a server-client type network service in which a large number of clients such as online games, chat, cloud, and music/video streaming services connect to the same server through an external network.

The present invention has been proposed to solve the above problems, and when a plurality of communication terminals connected to the same SDN switch communicate to a common destination terminal connected to another SDN switch, the flow table of the SDN switch connected to the destination communication terminal An object of the present invention is to provide a method for optimizing a generated flow policy that performs a duplicated operation into one policy and an SDN switch for the same.

A method for optimizing a flow table in a Software Defined Networking (SDN) switch according to an embodiment includes: requesting a flow policy from an SDN controller and receiving a flow policy from the SDN controller in response thereto; Identifying a flow policy that performs the same operation as the received flow policy in the flow table; And a value of a matching field item that matches each other among the matching field items of the identified flow policy and the received flow policy is maintained, and the value of the matching field item that does not match is replaced with a null value to redefine one flow policy. And registering in the flow table.

In the identifying step, a flow policy having the same input/output port number as the input/output port number defined in the received flow policy in the flow table may be identified as a flow policy that performs the same operation.

The registering may include creating a virtual flow table including the received flow policy and the identified flow policy; Redefining the received flow policy and the identified flow policy as one flow policy in the virtual flow table; Deleting the identified flow policy from the flow table and registering the redefined one flow policy; And deleting the virtual flow table.

The redefining may include maintaining a value of a matching field item among matching field items of the received flow policy and the identified flow policy, and replacing a value of a matching field item that does not match with a null value, You can create policies.

A Software Defined Networking (SDN) switch for optimizing a flow table according to an embodiment includes: a processor; And a memory for storing instructions executable by the processor and the flow table, wherein the processor requests a flow policy from the SDN controller and receives a flow policy from the SDN controller in response thereto; Identifying a flow policy that performs the same operation as the received flow policy in the flow table; Among the matching field items of the identified flow policy and the received flow policy, the value of the matching field item that matches each other is maintained, and the value of the matching field item that does not match is replaced with a null value to redefine it to one flow policy. It can be registered in the flow table.

The processor may identify a flow policy having the same input/output port number as the input/output port number defined in the received flow policy in the flow table as a flow policy that performs the same operation.

The processor generates a virtual flow table including the received flow policy and the identified flow policy, redefines the received flow policy and the identified flow policy as one flow policy in the virtual flow table, The identified flow policy may be deleted from the flow table, the redefined one flow policy may be registered, and the virtual flow table may be deleted.

The processor maintains a value of a matching field item among matching field items of the received flow policy and the identified flow policy in the virtual flow table, and replaces a value of a non-matching field item with a null value. One flow policy can be created.

According to one aspect, secure high QoS quality for network services through an efficient flow table optimization method in a server-client environment where SDN-based technology is applied, for example, providing online games, chat, cloud, music and video streaming services. Is possible.

According to an embodiment, since a separate device for optimizing a flow table is not required, and only some memory areas for utilizing a virtual flow table are dynamically allocated and used, initial construction and related maintenance costs are less consumed.

Due to the nature of SDN switches that have dependencies on hardware chipsets and memory devices, more SDN switch equipment is required in a large-scale network environment that exceeds the maximum size of the flow table. You lose. Therefore, it leads to a reduction in the initial network construction cost.

1 is a diagram showing an SDN-based network environment.
FIG. 2 is a diagram illustrating a flow policy registered in the second SDN switch of FIG. 1.
3 is a diagram illustrating an SDN-based network environment according to an embodiment of the present invention.
4 is a diagram showing a connection state between two SDN switches and three communication terminals according to an embodiment of the present invention.
5 is an example of a flow policy registered in the flow table of the first SDN switch of FIG. 4.
6 is an example of a flow policy registered in the flow table of the second SDN switch of FIG. 4.
7 is a diagram illustrating a flow table of the first SDN switch of FIG. 4.
8 is a diagram showing a flow table of the second SDN switch of FIG. 4.
9 is a diagram showing a virtual flow table according to an embodiment of the present invention.
10 is a diagram illustrating a process of optimizing a flow policy of each virtual flow table of FIG. 9.
11 is a diagram illustrating a process of registering a flow policy of a virtual flow table optimized in FIG. 10 to a second SDN switch.
12 is a diagram illustrating a finally updated flow table of a second SDN switch according to an embodiment of the present invention.
13 to 16 are diagrams illustrating a communication process between a first communication terminal and a third communication terminal based on an optimized flow table according to an embodiment of the present invention.
17 to 20 are diagrams illustrating a communication process between a second communication terminal and a third communication terminal based on an optimized flow table according to an embodiment of the present invention.
21 is a flowchart illustrating a method of optimizing a flow table in an SDN switch according to an embodiment of the present invention

The above-described objects, features, and advantages will become more apparent through the following detailed description in connection with the accompanying drawings, whereby those of ordinary skill in the technical field to which the present invention pertains can easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating an SDN-based network environment according to an embodiment of the present invention. Referring to FIG. 3, the SDN-based network includes an SDN controller 310, a plurality of SDN switches 320, and a plurality of communication terminals 330. In this embodiment, the SDN switch 320 is an entity constituting a network, and includes a mobile communication base station, a base station controller, a gateway, a router, etc., but is not particularly limited in type, and receives packets and performs routing processing. Covers network equipment.

The SDN controller 310 performs a function of managing the SND switches 320 in the network, and centrally manages and controls the plurality of SDN switches 32. The SDN controller 310 may be implemented with software that performs functions such as topology management, path management related to packet processing, link discovery, and packet flow management. The SDN controller 310 may transmit and receive information according to the SDN switch 320 and the OpenFlow protocol. When the SDN controller 310 receives a packet-in message from the SDN switch 320, it extracts the path of the packet and transmits it to the SDN switch 320 through a packet-out message. The flow policy of the flow table of the SDN switch 320 is registered.

The SDN switch 320 performs a function of processing a packet under the control of the SDN controller 310. As described above, the SDN switch 320 includes a mobile communication base station, a base station controller, a gateway, a router, etc., and includes all equipment processing packets in an SDN-based network environment. In the present embodiment, for convenience of explanation, the SDN switch 320 is mainly described in the case of an open flow switch. When receiving a packet from the connected communication terminal 330, the SDN switch 320 checks whether there is a flow policy for processing the received packet, and if there is no flow policy, the SDN switch 320 sends the packet to the buffer first in order to inquire where to send the packet. It stores and transmits some data including the header of the packet to the SDN controller 310 through a packet-in message, receives a flow policy from the SDN controller 310 through a packet-out message, registers it in the flow table, and stores it in the buffer. Process the packet.

The SDN switch 320 may include a memory, a memory controller, one or more processors (CPUs), a peripheral interface, an input/output (I/O) subsystem, an input device, and a communication circuit. The memory may include high-speed random access memory, and may also include one or more magnetic disk storage devices, nonvolatile memory such as flash memory devices, or other nonvolatile semiconductor memory devices. The memory may store instructions executable by the processor and may also store the flow table. Access to memory by other components such as the processor and peripheral interfaces can be controlled by the memory controller. The memory can store various types of information and program instructions, and programs are executed by the processor. The peripheral interface connects the input/output peripheral devices with the processor and memory. One or more processors execute various software programs and/or sets of instructions stored in memory to perform various functions for the system and process data. The I/O subsystem provides an interface between input and output peripherals, such as display devices and input devices, and peripheral interfaces. The communication circuit performs communication through an external port or by an RF signal. The communication circuit converts the electrical signal to an RF signal or vice versa, through which it can communicate with a communication network, other mobile gateway devices and communication devices. The processor of the SDN switch 320 may perform the methods and operations described below according to instructions stored in the memory.

The communication terminal 330 is a device that uses a communication service in an SDN-based network environment, for example, a user terminal such as a personal computer, a smartphone, and a tablet PC, and a game service, chat, cloud, music/video streaming service, etc. Includes the serving server. In this embodiment, at least two or more communication terminals are connected to one SDN switch to perform communication to a destination communication terminal connected to another SDN switch. Hereinafter, when a plurality of communication terminals connected to the same SDN switch communicate to a common destination terminal connected to another SDN switch, a flow policy for performing a redundant operation generated in the flow table of the SDN switch connected to the destination communication terminal is described as one flow policy. A method of optimizing by policy will be described in detail with reference to the drawings.

4 is a diagram showing a connection state between two SDN switches and three communication terminals according to an embodiment of the present invention. 4, two SDN switches 421 and 422 are connected to the SDN controller 410 by establishing a control channel, and two communication terminals 431 and 432 are connected to the first SDN switch 421, and , One communication terminal 433 is connected to the second SDN switch 422.

The first communication terminal 431 attempts to send an IP packet to the third communication terminal 433. To this end, the first communication terminal 431 transmits an ARP request message to the first SDN switch 421 in order to find out the MAC address of the third communication terminal 433. Since the first SDN switch 421 does not know where to send the ARP request message received through port 1, the SDN controller sends a packet-in message including some header files of the ARP request message to the SDN controller 410. Send it to 410 to inquire about processing.

When receiving the packet-in message, the SDN controller 410 already obtains the information of the communication terminals 431, 432, 433 connected to each switch port when establishing a control channel with each SDN switch (421, 422). The location information of the communication terminal 433 is known. The SDN controller 410 transmits a flow modification message including a flow policy to the first SDN switch 421 so that the corresponding ARP request message is transmitted to the third communication terminal 433, and the first SDN switch ( 421) registers a flow policy based on the content of the message. At this time, the registered flow policy has a flow ID that does not overlap with other flow policies.

5 is an example showing a flow policy registered in the flow table of the first SDN switch 421. The flow table includes a flow ID field, a match field, an action field, and a timeout. ) Field, and as shown in Fig. 5, the registered flow policy has "a001" as the flow ID. According to the items in the matching field, the corresponding flow policy is "The source MAC address (Src MAC) is'a' and the source IP address (Src IP) is '10.0.0.1 in the header of the packet that has entered port 1 (In Port). In the case of', destination IP address (Dst IP) is '10.0.0.3' and Ethernet type is '0x0806 (=ARP packet type)', send out a packet through port 3 (Out Port)” For reference, the idle time defined in the timeout field of the flow table is the time that the flow policy is maintained according to the official OpenFlow standard specification defined by ONF. If there is no packet, the flow policy is automatically deleted because the idle time cannot be updated In the example shown in Fig. 5, if there is no packet matching the flow policy within 30 seconds, all the flow policies are deleted.

According to the flow policy of the first registered flow ID '001', the first SDN switch 421 has a source MAC address (Src MAC) of the first communication terminal 431 in the header of the packet that has entered the port 1 (In Port). An ARP request message having an address'a' and an Ethernet type of 0x0806 (= ARP packet type) is transmitted to the second SDN switch 422 through a port 3 (Out Port). Since the second SDN switch 422 does not know where to send the ARP request message received through port 1, it forwards the packet-in message including some header files of the ARP request message to the SDN controller 410 to the SDN controller 410 To inquire about processing.

Upon receiving the packet-in message from the second SDN switch 422, the SDN controller 410 modifies the flow to the second SDN switch 422 so that the corresponding ARP request message is transmitted to the third communication terminal 433. After transmitting the message, the second SDN switch 422 registers and registers a flow policy based on the content of the message. At this time, the registered flow policy has a flow ID that does not overlap with other flow policies.

6 is an example of a flow policy registered in the flow table of the second SDN switch 422. As shown in FIG. 6, the registered flow policy has'b001' as a flow ID. According to the items in the matching field, the corresponding flow policy is "The source MAC address (Src MAC) is'a' and the source IP address (Src IP) is '10.0.0.1 in the header of the packet that has entered port 1 (In Port). ', Destination IP address (Dst IP) is '10.0.0.3', and Ethernet type is 0x0806 (=ARP packet type), it means to send a packet through port 2 (Out Port)." Finally, the ARP request message received from the first SDN controller 421 is delivered to the third communication terminal 433 through the second port of the second SDN switch 422 in accordance with the flow policy shown in FIG. .

The third communication terminal 433 receiving the ARP request message from the first communication terminal 431 transmits the ARP response message to the first communication terminal 431 through the same process as described above. Accordingly, a flow policy of flow ID'a002' is newly registered to the first SDN switch 421, and a flow policy of flow ID'b002' is newly registered to the second SDN switch 422. The first communication terminal 431 knows the MAC address of the third communication terminal 433 through the ARP response message. Now, the first communication terminal 431 can exchange ICMP packets with the third communication terminal 433 with the corresponding MAC address. To this end, the first communication terminal 431 first transmits an ICMP request message to the third communication terminal 433 and receives an ICMP response message from the third communication terminal 433. In this process, a flow policy for processing an ICMP packet is registered in the first and second SDN switches 421 and 422 through the same process as described above. That is, a flow policy of flow ID'a003' and'a004' is newly registered to the first SDN switch 421, and a flow policy of flow ID'b003' and'b004' is newly registered to the second SDN switch 422. do. Since the first communication terminal 431 and the third communication terminal 433 transmit and receive only IP-type packets while the ARP table is not updated, the flow policy in which the Ethernet type is 0x0806 (= ARP packet type) is Idle Time has expired and all are deleted. Finally, only flow IDs'a003' and'a004' remain in the flow table of the first SDN switch 421, and only flow IDs'b003' and'b004' remain in the flow table of the second SDN switch 422. Remains and the rest is removed.

If the second communication terminal 432 also wants to communicate with the third communication terminal 433, the ARP packet is processed through the same process as the above-described process, and then the ICMP packet is processed. Since the second communication terminal 432 and the third communication terminal 433 transmit and receive only IP-type packets while not updating the ARP table, the flow policy in which the Ethernet type is 0x0806 (= ARP packet type) is Idle Time has expired and all are deleted. Finally, only flow IDs'a007' and'a008' remain in the flow table of the first SDN switch 421 as a flow policy for communication between the second communication terminal 432 and the third communication terminal 433, In the flow table of the second SDN switch 422, only the flow IDs'b007' and'b008' remain, and the rest are removed.

7 is a diagram illustrating a flow table of the first SDN switch of FIG. 4, and FIG. 8 is a diagram illustrating a flow table of the second SDN switch of FIG. 4. As a flow policy for communication between the first and second communication terminals 431 and 432 and the third communication terminal 433, as shown in FIG. 7, the flow ID'a003' in the flow table of the first SDN switch 421 Flow policies of','a004','a007', and'a008' are registered, and as shown in FIG. 8, flow IDs'b003','b004', and the flow table of the second SDN switch 422 are registered. Flow policies of'b007' and'b008' are registered.

However, referring to FIG. 8, flow ID b003 and flow ID b007 are flow policies that perform an operation of sending a packet from port 1 of the second SDN switch 422 to port 2, and the two flow policies are Only the source MAC address and the source IP address are different, and the operation performed by the second SDN switch 422 is the same. Flow ID b004 and flow ID b008 are flow policies that perform an operation of sending a packet from port 2 of the second SDN switch 422 to port 1, and the two flow policies are only the destination MAC address and the destination IP address. However, the operation performed by the second SDN switch 422 is the same. The SDN controller 410 manages the flow policy by recognizing it as a different flow policy and assigning a unique flow ID because some matching conditions are different even though the operation is performed identically. However, the greater the number of communication terminals connected to the same SDN switch to communicate with the common destination communication terminal, and the greater the number of SDN switches connected to the destination communication terminal, the proportionally the SDN switch connected to the destination communication terminal. In the flow table, flow policies that perform redundant operations are bound to increase. As the flow policies increase in this way, it takes a lot of time to process packets of the SDN switch, and it causes the performance of the switch itself to deteriorate. Hereinafter, a method of optimizing a flow policy in the second SDN switch 422 will be described in detail.

Among the flow policies registered in the second SDN switch 422 of FIG. 8, two flow policies with flow IDs'b003' and'b007' performing the same operation of sending a packet from port 1 to port 2 overlap each other. Also, two flow policies with flow IDs'b004' and'b008' that perform the same operation of sending a packet from port 2 to port 1 are also duplicated. The second SDN switch 422 generates a virtual flow table in which the input port and the output port have the same flow policy.

FIG. 9 is a diagram showing a virtual flow table according to an embodiment of the present invention, and FIG. 9A is a first virtual flow table with flow policies having an input port number of 1 and an output port number of 2, 9B is a second virtual flow table with flow policies having an input port number of 2 and an output port number of 1; The second SDN switch 422 maintains duplicate matching field items in the generated virtual flow table and replaces non-matching items with a null value ('-') to redefine one flow policy.

10 is a diagram illustrating a process of optimizing a flow policy of each virtual flow table of FIG. 9. 10A shows that in the first virtual flow table, the source MAC address (Src MAC) and the source IP address (Scr IP) do not match in the two flow policies, so they are replaced with a null value and the remaining items are maintained. It represents the redefined flow policy. 10(b) shows that the destination MAC address (Dst MAC) and the destination IP address (Dst IP) in the second virtual flow table are not matched items in the two flow policies, so they are replaced with a null value and the remaining items are kept. It represents the redefined flow policy.

FIG. 11 is a diagram illustrating a process of registering a flow policy of a virtual flow table optimized in FIG. 10 to a second SDN switch, and FIG. 12 is a diagram illustrating a last updated flow table of a second SDN switch. As shown in FIG. 11, the flow policy of the first virtual flow table optimized in FIG. 10(a) and the flow policy of the second virtual flow table optimized in FIG. 10(b) are the 2nd SDN switch 422 ) To be registered. Accordingly, as shown in FIG. 12, four flow policies are reduced to two flow policies. As shown in FIG. 12, flow policies with existing flow IDs'b007' and b008' are deleted, and flow policies with existing flow IDs'b003' and b004' have some matching field items Replaced by value.

In the following, it is verified whether the first and second communication terminals 431 and 432 can communicate with the third communication terminal 433 using the optimized flow table as shown in FIG. 12.

First, verifying whether the first communication terminal 431 can communicate with the third communication terminal 433 is as follows. 13 to 16 are diagrams illustrating a communication process between a first communication terminal and a third communication terminal according to an embodiment of the present invention. 13, the first communication terminal 431 connected to the first SDN switch 421 to find out the MAC address of the third communication terminal 433 for the purpose of IP communication with the third communication terminal 433 The ARP request message is transmitted to the first SDN switch 421. The transmitted message flows into port 1 of the first SDN switch 421, and the first SDN switch 421 looks up the flow table for processing the message. Since the header file information of the message matches the flow policy with the flow ID'a003', the message is forwarded to the second SDN switch 422 through the port 3 defined in the action field of the flow policy. Referring to FIG. 14, the second SDN switch 422 looks up a flow table for processing an ARP request message introduced through port 1. Since the header file information of the corresponding message matches the flow policy with the flow ID'b003', the request message is forwarded to the port 2 defined in the action field of the flow policy and finally transmitted to the third communication terminal 433. 15, the third communication terminal 433 receiving the ARP request message generates an ARP response message to transmit its MAC address to the first communication terminal 431 to the second SDN switch 422. Deliver. The second SDN switch 422 looks up the flow table to process the ARP response message introduced through the second port. Since the header file information of the response message matches the flow policy with flow ID'b004', the response message is forwarded through port 1 defined in the action field of the flow policy. Referring to FIG. 16, a first SDN switch 421 looks up a flow table for processing an ARP response message introduced through port 3. Since the header file information of the corresponding response message matches the flow policy with the flow ID'a004', the response message is forwarded to the port 1 defined in the action field of the corresponding flow policy and finally transmitted to the first communication terminal 431. The first communication terminal 431 can transmit and receive an ICMP request/response message with the third communication terminal 433 with the MAC address of the third communication terminal 433 included in the received ARP response message. It is the same as the previous ARP message transmission/reception process.

Next, verifying whether the second communication terminal 432 can communicate with the third communication terminal 433 is as follows. 17 to 20 are diagrams illustrating a communication process between a second communication terminal and a third communication terminal according to an embodiment of the present invention. 17, the second communication terminal 432 connected to the first SDN switch 421 to find out the MAC address of the third communication terminal 433 for the purpose of IP communication with the third communication terminal 433 The ARP request message is transmitted to the first SDN switch 421. The transmitted message flows into port 2 of the first SDN switch 421, and the first SDN switch 421 looks up the flow table for processing the message. Since the header file information of the message matches the flow policy with the flow ID'a003', the message is forwarded to the second SDN switch 422 through the port 3 defined in the action field of the flow policy. Referring to FIG. 18, the second SDN switch 422 looks up a flow table to process an ARP request message introduced through port 1. Since the header file information of the corresponding message matches the flow policy with the flow ID'b003', the request message is forwarded to the port 2 defined in the action field of the flow policy and finally transmitted to the third communication terminal 433. Referring to FIG. 19, a third communication terminal 433 receiving an ARP request message generates an ARP response message to transmit its MAC address to the second communication terminal 431 to the second SDN switch 422. Deliver. The second SDN switch 422 looks up the flow table to process the ARP response message introduced through the second port. Since the header file information of the response message matches the flow policy with flow ID'b004', the response message is forwarded through port 1 defined in the action field of the flow policy. Referring to FIG. 20, a first SDN switch 421 looks up a flow table for processing an ARP response message introduced through port 3. Since the header file information of the response message matches the flow policy with the flow ID'a004', the response message is forwarded to the port 2 defined in the action field of the corresponding flow policy and finally transmitted to the second communication terminal 432. The second communication terminal 431 can transmit and receive an ICMP request/response message with the third communication terminal 433 with the MAC address of the third communication terminal 433 included in the received ARP response message. It is the same as the previous ARP message transmission/reception process.

As described above, even if the flow table of the second SDN switch 422 is optimized, the two communication terminals 431 and 432 connected to the first SDN switch 421 are a third communication terminal connected to the second SDN switch 422. Communication is possible with (433) as the destination.

21 is a flowchart illustrating a method of optimizing a flow table in an SDN switch according to an embodiment of the present invention, and operates at the SDN switch 422 level without the intervention of the SDN controller 410. First, when the SDN controller 410 operates in the Re-active mode, when an unknown packet is received by the SDN switch 422, the SDN switch 422 uses a header file including some information of the corresponding packet to the SDN controller ( 410) and transmits a packet-in message. Through the packet-in message, the SDN controller 410 generates a flow modification message so that the SDN switch 422 transmits the packet to the destination and transmits it to the SDN switch 422. The SDN switch 422 registers a flow policy in its own flow table by using the information included in the received flow modification message. As described above, when an event in which the flow modification message is transmitted from the SDN controller 410 to the SDN switch 422 occurs, the event is triggered and the method of FIG. 21 is operated.

Referring to FIG. 21, in step S2101, the SDN switch 422 checks whether a flow modification message is received from the SDN controller 410. When the flow modification message is received, in step S2102, the SDN switch 422 extracts an input/output port number, which is an element for defining the flow of the packet, from the received flow modification message. The corresponding input/output port number is used to define a flow policy on which packets of the SDN switch 422 are sent, to which output ports.

The SDN switch 422 performs a process of extracting a flow policy having an input/output port number matching the extracted input/output port number from among N flow policies previously registered in its own flow table. Specifically, in step S2103, the SDN switch 422 extracts the input/output port number of the i (1<i≤N) th flow policy of its own flow table, and in step S2104, the input port of the i th flow policy It is checked whether the number matches the input port number extracted from the flow modification message in step S2102. If they match, in step S2105, the SDN switch 422 checks whether the output port number of the i-th flow policy and the output port number extracted from the flow modification message in step S2102 match. If the output port number also matches, the SDN switch 422 generates a virtual flow table using the i-th flow policy and the flow policy included in the flow modification message. The SDN switch 422 repeats steps S2103 to S2106 for all of the N flow policies previously registered in its own flow table. Therefore, the flow policy included in the flow modification message and the flow policy included in the flow modification message among the N flow policies registered in the flow table of the SDN switch 422 are the same. All flow policies are registered in one virtual flow table. The virtual flow table is similar to a form of an actual flow table in which a flow policy for processing packets flowing to the SDN switch 422 is registered and managed, but flow policies for processing an actual packet are not registered. Since the virtual flow table is a virtual temporary table for processing flow policies that perform overlapping operations, flow IDs are not assigned to flow policies registered in the virtual table, and are created that are removed when the optimization of the duplicate flow policies is completed. Have a cycle. For reference, since the created virtual table has a certain generation period, it is not necessary to allocate a fixed memory area inside the SDN switch 422, and the memory area is secured through dynamic allocation when necessary as much as the size of the buffer memory area. It can be utilized without giving a large load to (422).

When the generation of the virtual flow table is completed in this way, in step S2107, the SDN switch 422, except for the matching field items of the flow policies registered in the virtual flow table, non-matching items are null values. And redefine one flow policy. Substituting a null value means removing the matching condition item. In step S2108, the SDN switch 422 registers the flow policy optimized and defined as a single policy in the actual flow table as a unique flow policy. In this process, the SDN switch 422 deletes the existing overlapping flow policies and assigns a new flow ID to the optimized and defined flow policy to register, or leaves only one of the existing overlapping flow policies. The remaining flow policy can be modified according to the optimized and defined flow policy, while the remaining flow policy is deleted.

Meanwhile, when there is no flow policy in the actual flow table that matches the input/output port number of the flow policy included in the received flow modification message, in step S2110, the SDN switch 422 is included in the received flow modification message. A new flow policy is registered in the actual flow table according to the established flow policy.

When a new flow policy is registered in the actual flow table or the optimized flow policy is updated and registered, in step S2109, the SDN switch 422 transmits the finally registered flow policy information to the SDN controller 410.

While this specification includes many features, such features should not be construed as limiting the scope or claims of the invention. In addition, features described in separate embodiments herein may be combined and implemented in a single embodiment. Conversely, various features described in a single embodiment herein may be individually implemented in various embodiments, or may be properly combined and implemented.

Although the operations have been described in a specific order in the drawings, it should not be understood that such operations are performed in a specific order as shown, or as a series of consecutive sequences, or that all described operations are performed to obtain a desired result. . Multitasking and parallel processing can be advantageous in certain environments. In addition, it should be understood that classification of various system components in the above-described embodiments does not require such classification in all embodiments. The above-described program components and systems may generally be implemented as a package in a single software product or multiple software products.

The method of the present invention as described above may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. This process can be easily carried out by a person of ordinary skill in the art to which the present invention pertains, and thus will not be described in detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those of ordinary skill in the technical field to which the present invention belongs. It is not limited by the drawings.

110, 310, 410: SDN controller
120, 130, 320, 421, 422: SDN switch
121, 122, 131, 330, 431, 432, 433: communication terminal

Claims (9)

In a method for optimizing a flow table in a Software Defined Networking (SDN) switch,
Requesting a flow policy from an SDN controller and receiving a flow policy from the SDN controller in response thereto;
Identifying a flow policy that performs the same operation as the received flow policy in the flow table; And
Among the matching field items of the identified flow policy and the received flow policy, the value of the matching field item that matches each other is maintained, and the value of the matching field item that does not match is replaced with a null value to redefine it to one flow policy. The method comprising; registering in the flow table. The method of claim 1,
The identifying step,
And identifying a flow policy having the same input/output port number as the input/output port number defined in the received flow policy in the flow table as a flow policy performing the same operation. The method of claim 1,
The registering step,
Generating a virtual flow table including the received flow policy and the identified flow policy;
Redefining the received flow policy and the identified flow policy as one flow policy in the virtual flow table;
Deleting the identified flow policy from the flow table and registering the redefined one flow policy; And
And deleting the virtual flow table. The method of claim 3,
The redefining step,
A flow policy is generated by maintaining a value of a matching field item among matching field items of the received flow policy and the identified flow policy and replacing a value of a matching field item that does not match with a null value. How to do it. In the SDN (Software Defined Networking) switch that optimizes the flow table,
Processor; And
Including; a memory for storing the flow table and instructions executable by the processor,
The processor,
Requesting a flow policy from the SDN controller and receiving a flow policy from the SDN controller in response thereto;
Identifying a flow policy that performs the same operation as the received flow policy in the flow table;
Among the matching field items of the identified flow policy and the received flow policy, the value of the matching field item that matches each other is maintained, and the value of the matching field item that does not match is replaced with a null value to redefine it to one flow policy. SDN switch, characterized in that to register in the flow table. The method of claim 5,
The processor,
And a flow policy having the same input/output port number as the input/output port number defined in the received flow policy in the flow table as a flow policy performing the same operation. The method of claim 5,
The processor,
Generate a virtual flow table including the received flow policy and the identified flow policy, redefine the received flow policy and the identified flow policy as one flow policy in the virtual flow table, and And deleting the identified flow policy, registering the redefined one flow policy, and deleting the virtual flow table. The method of claim 7,
The processor,
In the virtual flow table, one flow policy by maintaining the value of the matched field item among the matching field items of the received flow policy and the identified flow policy, and replacing the value of the matching field item that does not match with a null value. SDN switch, characterized in that to generate a. A computer program recorded on a recording medium as a computer program for executing the method according to any one of claims 1 to 4 through a computer system.

Images