KR101786623B1 - Method, apparatus and computer program for handling broadcast of software defined network - Google Patents

Abstract

The present invention relates to a method for a controller to support broadcasting in a software defined network, comprising the steps of: calculating at least one broadcasting path; A switch for controlling a switch to classify broadcast packets into at least one group according to a preset reference, match the broadcast paths to each group, and process the broadcast packets belonging to each group according to a matched broadcasting path; step; If the topology changes, the broadcast path associated with the topology change is recalculated to reflect the topology change, and broadcast packets that are matched to the broadcast path that is not related to the topology change are not matched to the broadcast path before the topology change And controlling the switch so as to process it without delay.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM FOR HANDLING BROADCAST OF SOFTWARE DEFINED NETWORK FIELD OF THE INVENTION [0001]

The present invention relates to a method for controlling a software defined network. More particularly, the present invention relates to a method for supporting broadcasting in a software defined network.

Software Defined Networking (SDN) is a technology that manages all the network devices in the network by an intelligent central management system. In the SDN technology, a controller provided in a software form instead of a control operation related to packet processing performed in a network device of existing hardware type has a merit in that it can develop and assign various functions over an existing network structure .

The SDN system generally comprises a controller server for controlling the entire network, a plurality of open flow switches controlled by the controller server for processing packets, and a host corresponding to a lower layer of the open flow switch. Here, the open flow switch is only responsible for transmitting and receiving packets, and routing, management, and control of the packets are all performed in the controller server. In other words, separating the data planes and control planes that form the network equipment is the basic structure of the SDN system.

Open Networking Foundation, "OpenFlow Specification 1.2.0"

It is an object of the present invention to provide a method for more efficiently supporting broadcasting in a software defined network. More specifically, the present invention aims to prevent a broadcasting delay due to a change in topology by operating a plurality of broadcasting paths of a network.

A method for a controller to support broadcasting in a software defined network according to an embodiment of the present invention includes the steps of: calculating at least one broadcasting path; A switch for controlling a switch to classify broadcast packets into at least one group according to a preset reference, match the broadcast paths to each group, and process the broadcast packets belonging to each group according to a matched broadcasting path; step; If the topology changes, the broadcast path associated with the topology change is recalculated to reflect the topology change, and broadcast packets that are matched to the broadcast path that is not related to the topology change are not matched to the broadcast path before the topology change And controlling the switch so as to process it without delay.

Further, an apparatus for supporting broadcasting in a controller in a software defined network according to an embodiment of the present invention includes: a communication unit for communicating with a switch; And at least one broadcasting path, classifies the broadcast packets into at least one group according to a preset reference, matches the broadcasting path to each of the groups, and broadcast packets belonging to each group are broadcast And if the topology has changed, the broadcasting path associated with the topology change is calculated again to reflect the topology change, and the broadcast path associated with the topology change is broadcast, And a control unit for controlling the switch to process the cast packet without delay by applying a matched broadcasting path before the topology change.

In accordance with an embodiment of the present invention, a computer program stored in a computer-readable recording medium for performing a process of supporting broadcasting in a software-defined network includes: a function of calculating at least one broadcasting path; A function of classifying broadcast packets into at least one group according to a preset reference, matching the broadcast paths to each group, and controlling the switch to process the broadcast packets belonging to each group according to a matched broadcasting path ; If the topology changes, the broadcast path associated with the topology change is recalculated to reflect the topology change, and broadcast packets that are matched to the broadcast path that is not related to the topology change are not matched to the broadcast path before the topology change And controls the switch to process without delay.

According to the present invention, the broadcasting path is calculated by reflecting the network operation information, and the broadcasting is processed by a plurality of paths, so that the network resource can be efficiently used. Further, according to the present invention, when the topology is changed, the broadcast packet can be processed by applying the route irrelevant to the change, thereby preventing broadcasting delay.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a drawing for describing software defined networking.
2 is a diagram for explaining a method of processing broadcasting based on a spanning tree
3 is a diagram for explaining a broadcasting support method according to an embodiment of the present invention;
4 is a view for explaining a method of modifying a spanning tree when a topology is changed according to an embodiment of the present invention;
5 is a flowchart illustrating a method of supporting broadcasting according to an embodiment of the present invention.

It is to be understood that the present invention is not limited to the description of the embodiments described below, and that various modifications may be made without departing from the technical scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

In the drawings, the same components are denoted by the same reference numerals. And in the accompanying drawings, some of the elements may be exaggerated, omitted or schematically illustrated. It is intended to clearly illustrate the gist of the present invention by omitting unnecessary explanations not related to the gist of the present invention. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should be understood that the term " flow rule " in the context of the present invention means a network policy applied by a controller server in a software defined network in the context of a skilled artisan.

Further, in the present specification, the open flow switch 200 can be understood as a concept including a switch supporting only an open flow protocol, a virtual switch supporting an open flow protocol, and a general L2 switch supporting an open flow protocol.

1 is a diagram for explaining a configuration of a software defined network. Referring to FIG. 1, a software defined network may include a controller server 100, network equipment 200, and a host 300. The network device 200 and the host 300 may be referred to as a node, and a link may denote a connection between two nodes.

The controller server 100 manages the network equipment 200 and centrally manages and controls the plurality of network equipment 200. Specifically, the controller server 100 includes an application program that performs functions such as topology management, path management related to packet processing, link discovery, and packet flow flow management, And can be implemented in a mounted form.

The network device 200 functions to process packets under the control of the controller server 100. Examples of the network equipment 200 include a mobile communication base station, a base station controller, a gateway equipment, a wired network switch, and a router.

In the software defined network, the controller server 100 and the open flow switch 200 exchange information with each other. The open flow protocol is widely used as a protocol for this. That is, the open flow protocol is a standard that allows the controller server 100 and the open flow switch 200 to communicate with each other.

According to the open flow protocol, the switch 200 exchanges information with the controller server 100 via a control channel, and includes one or more flow tables for pipeline processing, a group table, A meter table and / or a network interface for packet delivery.

On the other hand, the way data transmitted by a transmitting host is transmitted to all hosts connected to the network is called broadcasting. The processing of transmitted data, that is, whether data is received or dropped, is determined based on the destination address of the receiving host.

Broadcasting increases the traffic dramatically because data is transmitted throughout the network, especially if there is a loop in the broadcasting path. Therefore, the conventional network has prevented the loop phenomenon by using the spanning tree protocol which is the distributed protocol. A spanning tree refers to a network configuration in which all nodes in the topology are linked by links and no loops are included.

2 is a diagram for explaining a method of processing broadcasting based on a spanning tree.

The broadcast packets transmitted by the host A 210 in the network shown in FIG. 2A are transmitted to all the hosts connected to the network, that is, the host B 220, the host C 230, the host D 240 and the host E 250 .

FIG. 2B is a topology graph of the network of FIG. 2A connecting switches and links. In the network as shown in FIG. 2B, the spanning tree may be configured as shown in FIG. 2C, which is a tree structure in which all nodes are connected by a link and no loop occurs. The spanning tree can be computed using various algorithms according to conventional techniques.

The broadcast packet transmitted from the host A 210 in the network as shown in FIG. 2A can be transmitted to all the hosts in the network along the path as shown in FIG. 2C.

The switch 260 receiving the broadcast packet of the host A 210 forwards the packet to the switch 261 according to the path of FIG. 2C, the switch 261 forwards the broadcast packet to the connected host 220, The switch 262 forwards the packet to the switch 262, the switch 262 forwards the corresponding broadcast packet to the connected host D 240, and at the same time forwards the packet to the switches 263 and 264 according to the path of FIG. The received switches 263 and 264 may forward the broadcast packet to the connected host C 230 and host E 250.

In a conventional network structure, broadcasting is supported in a legacy switch, and a legacy switch can support broadcasting in such a manner that only a link constituting a spanning tree is used for broadcasting according to a spanning tree protocol.

On the other hand, in a software defined network, the broadcasting path can be set as an open flow protocol under the control of the controller. That is, in a software defined network, a controller can support broadcasting by calculating a broadcasting path based on a spanning tree and transmitting a flow rule for packet processing to the switch.

Furthermore, the controller can calculate the spanning tree considering the cost of moving between nodes and / or the weight of the link. The spanning tree, in which all nodes are connected by a link, there is no loop, and at the same time the cost of moving between nodes is minimum, is called MST (Minimum Spanning Tree). The cost of moving between nodes and / or the weight of the link may be calculated taking into account the network conditions.

However, if the network topology configuration changes, that is, network components are added and / or deleted, the controller must recalculate the MST and re-establish the broadcast path. In such a series of processes, latency may occur in the broadcasting process.

Furthermore, when the topology is conventionally changed, the entire broadcasting path is recalculated without regard to its form. That is, even if the change does not affect the entire path, the MST recalculation and the broadcasting path change are required, and there is a problem that the delay occurs.

The present invention is intended to solve the above problems.

According to the embodiment of the present invention, the controller has a feature of operating a plurality of MSTs simultaneously for broadcasting processing. If multiple broadcasting MSTs are used to set the broadcasting path, the route to which the MST is applied irrespective of the change is applied to the broadcasting without delay even if the topology changes, thereby increasing the efficiency of the entire network.

Further, according to the embodiment of the present invention, when a topology configuration is added, a broadcast path can be set by reflecting only the configuration added to the MST before the topology change, without recomputing the entire MSTs.

Specific examples according to the present invention will be described below with reference to the accompanying drawings.

3 is a diagram for explaining a broadcasting support method according to an embodiment of the present invention.

In a topology such as 300, the MST can be calculated in a plurality of ways such as 301, 302, 303,

According to the embodiment of the present invention, the network operating information acquired using the open flow protocol can be utilized as a weight for calculating the MST.

For example, the open flow protocol supports a port status message (OFPT_PORT_STATUS message) and / or a multipart request message (OFPT_MULTIPART_REQUEST message) type as a message type. Using this, the controller can acquire the network operation information such as the bandwidth and traffic amount of the link, and utilize the obtained network operation information as the weight of the MST calculation.

According to the embodiment, real-time network operation information is reflected in the MST calculation, and since a plurality of MSTs are operated, the resources of the entire network can be efficiently used.

More specifically, according to an embodiment of the present invention, the controller can obtain bandwidth-specific bandwidth information from the port status message of the switch and obtain information on traffic usage of the link from the multipart request message. Then, the controller can calculate a plurality of MSTs by using the obtained network operation information as a weight of the MST calculation.

The present invention is characterized by utilizing the obtained network operation information as a weight of the MST calculation. An algorithm for calculating a plurality of MSTs using the weight values can be variously applied according to the conventional technique.

Returning to the description of FIG. 3, a concrete method of utilizing four MSTs such as 301, 302, 303 and 304 as a broadcasting path in a topology such as 300 is as follows.

First, the controller can group broadcasting packets into four groups according to an arbitrary criterion. This is because a particular MST is uniquely matched to each group and a broadcast packet belonging to the group is processed by a route using a matched MST.

In particular, according to an embodiment of the present invention, the controller can assign a group to a packet using a maskable field in a header of the packet.

The open flow protocol specifies the contents of the header match fields in advance. For example OXM_OF_ETH_DST, OXM_OF_ETH_SRC, OXM_OF_VLAN_VID, OXM_OF_IPV4_SRC, OXM_OF_IPV4_DST, OXM_OF_ARP_SPA, OXM_OF_ARP_TPA, OXM_OF_ARP_SHA, OXM_OF_ARP_THA, OXM_OF_IPV6_SRC, OXM_OF_IPV6_DST OXM_OF_IPV6_FLABEL and are defined as being the mask.

The controller can thus assign a group to the packet using the field of the maskable header. For example, when broadcasting packets are classified into four groups using an Ethernet source MAC address, the controller assigns the first group of packets with the source MAC address of 00 as the first group, the second group as the packets with the address 01, 3, and 11 packets can be classified into the fourth group.

Thereafter, the controller assigns the MST 301 to the first group, the MST 302 to the second group, the MST 303 to the third group, and the MST 304 to the fourth group, and to transmit a flow rule for setting a broadcasting path conforming to the allocated MST have.

For example, when Port 1, Port 2, and Port 3 of the switch 260 of FIG. 2 are connected to the switches 263, 262, and 261, respectively, Table 1 below shows a flow of setting a broadcasting path to the switch 260 according to MST in FIG. It is an example of a rule.

Match Fields Instructions OXM_OF_ETH_SRC (Ethernet source MAC address) OXM_OF_ETH_DST
(Ethernet destination MAC address) One 00: 00: 00: 00: 00: 00 /
00: 00: 00: 00: 00: 03 FF: FF: FF: FF: FF: FF Output: Port 1 2 00: 00: 00: 00: 00: 01 /
00: 00: 00: 00: 00: 03 FF: FF: FF: FF: FF: FF Output: Ports 1 and 2 3 00: 00: 00: 00: 00: 10 /
00: 00: 00: 00: 00: 03 FF: FF: FF: FF: FF: FF Output: ports 2,3 4 00: 00: 00: 00: 00: 11 /
00: 00: 00: 00: 00: 03 FF: FF: FF: FF: FF: FF Output: Port 3

The first row of Table 1 indicates that the first group of broadcast packets received at switch 260 should be forwarded to switch 263 over port 1 according to MST 301, And port 2 to switch 263 and switch 262, respectively.

While the third line indicates that the third group of broadcast packets received at switch 260 should be forwarded to switch 262 and switch 261 via port 2 and port 3 according to MST 303, To the switch 261 via port 3. [

4 is a diagram for explaining an example of setting a broadcasting path when the topology is changed.

In the example as shown in FIG. 4A, it can be considered that the link 265 connecting the switch 260 and the switch 263 is deleted.

In this case, according to the conventional art, since the topology is changed, the MST is calculated again, and the broadcasting path reflecting the calculated MST should be transmitted again in the form of a flow change message.

However, according to the embodiment of the present invention, the link 265 is included in the MST 301 and the MST 302 in FIG. 3, but is independent of the MST 303 and the MST 304. Therefore, the broadcasting of the group matched to the MST 303 and the MST 304 can be performed by applying the conventional rule without changing all the flow rules.

That is, only the first row and the second row in the flow rule of Table 1 need to be changed, and the third row and the fourth row can be consistently applied before and after the topology change without changing.

According to the embodiment of the present invention, even if the topology is changed, broadcast packets belonging to the group matched with the MST regardless of the topology change can be processed without changing the flow rules.

On the other hand, the MST associated with the topology change can be recalculated to reflect the changes. Particularly, according to the embodiment of the present invention, the packet of the group can be processed or dropped by applying another MST, that is, MST irrelevant to the topology change, before a new flow rule according to the topology change is applied.

According to another embodiment of the present invention, in the example shown in FIG. 4A, it can be considered that the link 266 is connected through the port 3 of the switch 264 so that another switch 267 is added. (Port 1 of switch 264 is connected to switch 262, port 2 is connected to switch 261)

In this case, since the topology has been changed according to the prior art, the MST is calculated again and the broadcasting path reflecting the calculated MST should be transmitted again in the form of a flow change message.

However, the link 266 and the node 267 installed in the network edge do not affect the entire switch, but only the switch 264. Therefore, according to the embodiment of the present invention, the entire MST is not re-calculated but can be simply processed by a method of modifying the flow rule of the corresponding switch by reflecting only the configuration added to the MST before the topology change. The modified MST is shown in FIG. 4B.

More specifically, when the switch 264 receives the broadcast packet, the controller transmits the first group and the fourth group through ports 1 and 3, and the second group and the third group transmits through port 2 and port 3 We will change the flow rule.

5 is a flowchart illustrating a method of supporting broadcasting in a software defined network according to an embodiment of the present invention.

In step 510 of FIG. 5, the controller can calculate a plurality of MSTs for setting the broadcasting path in the network topology of the corresponding point in time.

Particularly, according to the embodiment of the present invention, the controller can utilize the network operation information as the weight of the MST calculation.

More specifically, the controller receives the port status message from the switch, obtains bandwidth-specific bandwidth information, and receives the multi-part request message to obtain information on traffic usage of the link. Then, the controller can calculate a plurality of MSTs by using the obtained network operation information as a weight of the MST calculation. The algorithm for calculating a plurality of MSTs using the weight values may be variously applied according to conventional techniques.

In step 520, the controller classifies the broadcast packets into groups of the calculated number of MSTs, and allocates MSTs for each group.

In particular, according to an embodiment of the present invention, the controller is capable of assigning a group to a packet using a maskable field in a header of the packet.

And more specifically, the controller is described a value dividing a masking possible field values, etc. OXM_OF_ETH_DST, OXM_OF_ETH_SRC, OXM_OF_VLAN_VID, OXM_OF_IPV4_SRC, OXM_OF_IPV4_DST, OXM_OF_ARP_SPA, OXM_OF_ARP_TPA, OXM_OF_ARP_SHA, OXM_OF_ARP_THA, OXM_OF_IPV6_SRC, OXM_OF_IPV6_DST and OXM_OF_IPV6_FLABEL the match field of the flow rules in a certain range Broadcast packets can be classified into groups.

Further, the controller may assign a MST to each group and send a flow rule to each switch to set a broadcasting path that follows the assigned MST. (Step 530)

On the other hand, step 540 and subsequent steps are for an example of controlling the broadcasting path when the topology is changed.

A case where some configuration of the topology is deleted in step 570 can be considered.

In this case, since the topology has conventionally been changed, the MST is calculated again, and the broadcasting path reflecting the calculated MST must be transmitted to the entire network in the form of a flow change message.

However, according to the present invention, therefore, only the MST associated with the topology change need be recalculated without requiring all the flow rules to change. (Step 580). That is, broadcasting of the group matched to the MST irrespective of the topology change can be processed by applying the conventional flow rule.

On the other hand, the MST associated with the topology change can be recalculated to reflect the changes. Particularly, according to the embodiment of the present invention, a group of packets matched with the MST related to the topology change can be processed or dropped by applying another MST, that is, an MST irrelevant to the topology change, before the new flow rule is applied.

On the other hand, a case in which some configuration of the topology is added in step 540 can be considered. In such a case, the controller according to the embodiment of the present invention not only recalculates the entire MST, but reflects only the configuration added to the conventional MST, and only the flow rules of the switches related to the added configuration can be changed (step 550). (Step 560)

The embodiments of the present invention disclosed in the present specification and drawings are intended to be illustrative only and not intended to limit the scope of the present invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (6)

In a method for a controller to support broadcasting in a software defined network,
An A step of calculating at least one broadcasting path;
A switch for controlling a switch to classify broadcast packets into at least one group according to a preset reference, match the broadcast paths to each group, and process the broadcast packets belonging to each group according to a matched broadcasting path; step; And
When the topology is changed, the first broadcasting path related to the topology change is changed to reflect the topology change, and the broadcast packet belonging to the group matched with the second broadcasting path that is not related to the topology change, And controlling the switch to process the casting path without delay,
In the step C,
Wherein a broadcast packet belonging to a group matched with a first broadcasting path related to the topology change is transmitted to the switch through the second broadcasting path before the first broadcasting path is changed after the topology is changed, The method comprising the steps of: 2. The method according to claim 1,
Calculating a bandwidth and traffic amount of a link using a port status message (OFPT_PORT_STATUS message) and a multipart request message (OFPT_MULTIPART_REQUEST message) received from the switch;
And calculating at least one of the broadcasting paths reflecting the bandwidth and the amount of traffic. The method according to claim 1,
Generating a group of the broadcast packets by the calculated number of broadcasting paths, and matching the broadcasting path to the group; And
Transmitting a flow rule to the switch instructing to assign a group to the broadcast packet using a maskable field of a header of the packet and to process the broadcast packet of the group by applying a matched broadcasting path Lt; RTI ID = 0.0 > 1, < / RTI > 2. The method of claim 1,
If the topology configuration is added, reflecting the configuration added to the broadcasting path before the topology change, without recalculating all of the broadcasting paths for the entire topology; And
And deleting a flow rule for processing a broadcast packet belonging to a group matched with a broadcast path associated with the deleted configuration when the topology configuration is deleted. In a device that supports broadcasting in a controller in a software defined network,
A communication unit for communicating with the switch; And
At least one broadcasting path is calculated, at least one group of broadcast packets is classified into at least one group according to a predetermined criterion, each of the groups is matched with the broadcasting path, and broadcast packets pertaining to each group are matched broadcast And when the topology is changed, the first broadcasting path associated with the topology change is changed in accordance with the topology change, and the second broadcasting path related to the second broadcasting path and the group matched with the topology change- And a control unit for controlling the switch to process the broadcast packet belonging thereto without delay by applying a matched broadcasting path before the topology change,
Wherein the control unit applies the second broadcasting path before the first broadcasting path is changed after the topology is changed by changing the broadcasting path of the broadcast packet belonging to the group matched with the first broadcasting path related to the topology change And controls the switch to process the broadcast. A computer program stored in a computer-readable recording medium for performing processing in a software-defined network in which a controller supports broadcasting,
A function of calculating at least one broadcasting path;
A function of classifying broadcast packets into at least one group according to a preset reference, matching the broadcast paths to each group, and controlling the switch to process the broadcast packets belonging to each group according to a matched broadcasting path ;
When the topology is changed, the first broadcasting path related to the topology change is changed to reflect the topology change, and the broadcast packet belonging to the group matched with the second broadcasting path that is not related to the topology change, Performs a function of controlling the switch to process the casting path without delay,
The function of controlling the switch includes:
Wherein a broadcast packet belonging to a group matched with a first broadcasting path related to the topology change is transmitted to the switch through the second broadcasting path before the first broadcasting path is changed after the topology is changed, The computer program comprising the steps of:

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