KR20180057475A - Traffic explosion resolving apparatus and method for sdn-based passive optical networks - Google Patents

Abstract

Disclosed are an apparatus for resolving traffic congestion in a passive optical network (PON) based on a software defined network (SDN) and a method thereof. According to one embodiment of the present invention, the method for resolving traffic congestion performed by an SDN agent comprises the steps of: monitoring a transmission status of uplink traffic of a PON in real time to determine whether traffic is congested for a specific node; sending an event for the traffic congestion to an SDN control device if it is determined that the traffic congestion for the specific node has occurred; and changing a configuration of the PON according to a control signal received from the SDN control device to resolve the traffic congestion.

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus and a method for resolving a traffic congestion of a passive optical network based on SDN,

The present invention relates to an apparatus and a method for solving a traffic congestion of an SDN-based passive optical network, and more particularly, to a method and apparatus for solving a traffic congestion in a passive optical network (PON) , Hereinafter referred to as " SLA ") to solve traffic congestion.

PON technology is realized by connecting an optical line terminal (OLT) and a plurality of optical network units (ONUs) through a point-to-multipoint (P2MP) It is an optical network technology that provides high-speed data service. Typically, EPON (Ethernet PON) and GPON (Gigabit PON) series have been standardized by IEEE and ITU-T. The PON technology has a tree structure in which OLTs located in the Central Office and a plurality of ONUs located in the optical subscriber correspond to 1: N. At this time, the OLT performs packet transmission using a broadcast scheme to a plurality of ONUs, and conversely, a plurality of ONUs use a time division multiple access (TDMA) scheme to avoid collision between ONUs with the OLT And performs packet forwarding.

In this TDMA-based PON technology, a plurality of ONUs are connected to the OLT through one optical fiber, so a protocol is required for uplink traffic transmission without collision. When the new ONU is registered in the network, the OLT performs bandwidth allocation for uplink traffic transmission to the new ONU.

First, the OLT checks the bandwidth setting by the SLA based on the Buffer Status Report (BSR) (Report Message) received from a plurality of ONUs and allocates the up-time resource to each ONU. (Grant message) Transmits the packet stored in the buffer to the OLT for the allocated time. At this time, the SLA is set according to the contract of the communication service provider, and the network manager directly adjusts the bandwidth of the ONU according to the purpose of use, thereby preventing transmission of data exceeding the set bandwidth reference.

However, the static SLA structure occupies a guaranteed bandwidth even in an ONU having no uplink traffic, which causes a problem of deteriorating network efficiency. In order to compensate this, Dynamic Bandwidth Allocation (DBA) algorithm in the OLT performs dynamic bandwidth scheduling based on buffer state of the ONU, average transmission amount, and data priority. However, since this is also based on the bandwidth setting of the SLA, when the sudden traffic congestion occurs in a certain node, the problem can not be solved.

The present invention provides an apparatus and method for resolving traffic congestion by changing a configuration of a dynamic service level agreement (SLA) according to the real-time network conditions of an SDN-based passive optical network (PON).

According to an embodiment of the present invention, there is provided a traffic congestion solving method performed by an SDN agent, comprising the steps of: monitoring a transmission status of uplink traffic of the PON in real time to determine whether traffic is congested for a specific node; Transmitting an event for the traffic congestion to the SDN controller if it is determined that traffic congestion has occurred for the particular node; And changing the configuration of the PON according to the control signal received from the SDN control device to resolve the traffic congestion.

Wherein the determining step comprises determining a first buffer amount of the optical network units received through a buffer status report (BSR) of a plurality of optical network units (ONUs) interworking with the PON, Identifying a second buffer amount assigned to the first buffer; Calculating a difference between the first buffer amount and the second buffer amount and accumulating the difference for each ONU for a predetermined time; And determining that traffic congestion has occurred when the difference between the first buffer amount and the second buffer amount accumulated for each ONU is greater than a preset first threshold value.

Wherein the determining step comprises the steps of: collecting an amount of a packet drop generated for each of a plurality of ONUs associated with a PON; And determining that traffic congestion has occurred when the amount of the collected packet drops is greater than a second threshold value set for a predetermined time period, wherein the packet drop indicates that the amount of upstream traffic of the ONU exceeds a buffer size of the corresponding ONU May occur in the buffer.

Monitoring the transmission status of the PON upstream traffic in real time to determine whether traffic congestion for a specific node is eliminated; And transmitting an event for the traffic congestion resolution to the SDN control apparatus when it is determined that the traffic congestion for the specific node has been solved.

According to an embodiment of the present invention, a traffic congestion solving method performed by an SDN control device includes receiving an event for traffic congestion from an SDN agent; Confirming available resources available for the node where the traffic congestion has occurred; Changing the configuration of a service level agreement (SLA) according to whether the identified available resource exists; And sending the configuration of the modified SLA to the SDN agent.

The checking step may identify the available resources by using the total traffic capacity of the plurality of PONs linked through the SDN and the average transmission rate of each node.

Wherein the modifying comprises: storing the current SLA configuration if the identified available resources are present; And generating a new SLA configuration by adjusting a bandwidth of the node where the traffic congestion has occurred, wherein the generating step may change the maximum bandwidth of the node where the traffic congestion has occurred by a preset minimum change amount.

Receiving an event for traffic congestion resolution from the SDN agent; Determining whether the SLA configuration for the node where the traffic congestion has occurred is changed if an event for the traffic congestion dissolution is received; And restoring the SLA configuration to an existing SLA configuration if it is determined that the SLA configuration for the node where the traffic congestion has occurred is changed.

The SDN agent according to an embodiment of the present invention monitors the transmission status of the PON uplink traffic in real time and determines whether the traffic is congested for a specific node. A transmitting unit for transmitting an event for the traffic congestion to the SDN control apparatus when it is determined that traffic congestion has occurred for the specific node; And a changing unit for changing the configuration of the PON according to a control signal received from the SDN control apparatus to resolve the traffic congestion.

The determination unit may determine a first buffer amount of the optical network units received through a buffer status report (BSR) of a plurality of optical network units (ONUs) interlocked with the PON, The difference between the first buffer amount and the second buffer amount accumulated for each ONU for each predetermined time is calculated by checking the allocated second buffer amount, calculating the difference between the first buffer amount and the second buffer amount, It is determined that the traffic congestion has occurred.

Wherein the determination unit collects the amount of packet drop generated for each of the plurality of ONUs connected to the PON and determines that traffic congestion occurs when the amount of the collected packet drop is greater than a predetermined second threshold value for a predetermined time, Drop may occur in the buffer if the uplink traffic volume of the ONU exceeds the buffer size of the corresponding ONU.

Wherein the determination unit determines whether or not traffic congestion for a specific node is resolved by monitoring the transmission status of the PON upstream traffic in real time and if the traffic congestion for the specific node is resolved, Lt; RTI ID = 0.0 > SDN < / RTI >

An SDN control apparatus according to an embodiment of the present invention includes: a receiving unit for receiving an event for traffic congestion from an SDN agent; A confirmation unit for confirming available resources available for the node where the traffic congestion has occurred; A change unit configured to change a configuration of a service level agreement (SLA) according to whether the identified available resources exist; And a transmission unit for transmitting the configuration of the changed SLA to the SDN agent.

The confirmation unit can confirm the available resources by using the total traffic availability capacity of the plurality of PONs linked through the SDN and the average transmission rate of each node.

Wherein the changing unit stores a current SLA configuration and adjusts a bandwidth of a node where the traffic congestion occurs to generate a new SLA configuration when the identified available resources exist, The bandwidth can be changed by a predetermined minimum change amount.

The receiving unit receives an event for traffic congestion resolution from the SDN agent. When the event for the traffic congestion cancellation is received, the confirmation unit determines whether the SLA configuration for the node where the traffic congestion has occurred is changed , The changing unit can restore the existing SLA configuration when it is determined that the SLA configuration for the node where the traffic congestion has occurred is changed.

According to an exemplary embodiment of the present invention, traffic congestion can be resolved by changing the configuration of a dynamic service level agreement (SLA) according to the real-time network conditions of an SDN-based passive optical network (PON).

1 is a diagram illustrating a traffic congestion resolution system for an SDN-based passive optical network according to an embodiment of the present invention.
2 is a diagram illustrating a method of allocating upstream traffic bandwidth between an OLT and an ONU according to an embodiment of the present invention.
3 is a diagram illustrating an example of traffic congestion occurrence according to an SLA standard according to an embodiment of the present invention.
4 is a diagram illustrating an SLA configuration setting procedure according to a traffic congestion event according to an embodiment of the present invention.
5 is a diagram illustrating an SLA configuration setting procedure according to an event of traffic congestion resolution according to an embodiment of the present invention.
6 is a diagram illustrating an SLA configuration setting procedure according to an event of traffic overload according to an exemplary embodiment of the present invention.
7 is a view illustrating an SLA configuration setting procedure according to a case where traffic congestion occurs consecutively in two nodes according to an embodiment of the present invention.
FIG. 8 is a view illustrating an SLA configuration setting procedure according to a temporary example of the present invention when traffic congestion occurs at two nodes at the same time.
9 is a diagram illustrating an embodiment of an SLA configuration change according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a traffic congestion resolution system for an SDN-based passive optical network according to an embodiment of the present invention.

1, it is assumed that there is a PON system that operates three nodes such as ONU H, ONU B, and ONU T 120. Suppose that at certain times an important game like the Olympic final is held and a lot of people are driven to the ONU T node. Accordingly, traffic is rapidly concentrated in the ONU T node, and traffic in a range exceeding the maximum bandwidth defined in the SLA of the ONU T node is discarded without being allocated a bandwidth. This causes many users to experience dissatisfaction with the service.

This problem is caused by the fact that the bandwidth available to the user depends on the SLA at the time of the initial contract and the static SLA setting by the manual input of the conventional network manager. However, SDN technology has recently been applied to PON systems. The SDN-based PON system concentrates the intelligence of the network on the SDN control device 130 to provide a global view of the overall network status through abstraction of the network service and enables more flexible and efficient network management.

The SDN-based PON system changes to a new SLA configuration dynamically according to the network conditions and reflects the new policy in the network, thereby enabling smart network operation according to the real-time network situation. The present invention provides a method for solving the traffic congestion through dynamic SLA operation according to the real-time network situation in the SDN-based PON system.

As shown in FIG. 1, if the network utilization is confirmed by checking the network utilization rate of other nodes according to the current SLA setting, the ONU D and the ONU B node can dynamically relax the SLA reference and dynamically increase SLA Can be applied. Specifically, the OLT 110 configuring the SDN-based PON system can monitor the real-time uplink traffic situation of the plurality of ONUs 120. At this time, the SDN agent 111 included in the OLT 110 can determine whether traffic is congested for a specific node based on the real-time uplink traffic situation of the monitored ONUs 120. SDN agent 111 may send an event for traffic congestion to SDN controller 130 if it is determined that traffic congestion has occurred for a particular node.

Thereafter, the SDN controller 130 generates a new candidate SLA configuration according to the event for the traffic congestion received from the SDN agent 111, changes the current SLA configuration to a new candidate SLA configuration, Can be generated.

The SDN control unit 130 transmits the generated control signal to the SDN agent 111 and the OLT 110 including the SDN agent 111 transmits the control band of the plurality of ONUs 120 in accordance with the received control signal Can be changed.

2 is a diagram illustrating a method of allocating upstream traffic bandwidth between an OLT and an ONU according to an embodiment of the present invention.

Referring to FIG. 2, the OLT 110 may perform bandwidth allocation for uplink traffic transmission to a specific ONU. The ONU 120 may report information on its current buffer status to the OLT 110 by transmitting a Report message through a buffer status report (BSR) as in step 210. [

The OLT 110 then checks the guaranteed bandwidth of each ONU 120 based on the Report message received from the plurality of ONUs 120 as in step 220 and allocates time resources to the corresponding ONUs 120 have. At this time, the OLT 110 can allocate a time resource by transmitting a Grant message to each ONU 120. Each ONU 120 may transmit a packet stored in the buffer to the OLT 110 for a time allocated to the ONU 120 as shown in step 230.

At this time, traffic congestion may occur in the ONU 120 due to an unexpected increase in traffic. Specifically, the traffic congestion phenomenon is a phenomenon in which the traffic suddenly increases in a specific ONU 120, and there are two methods for determining whether there is an up traffic congestion.

The first method uses a difference between a first buffer amount reported through the buffer status report of a specific ONU 120 in the OLT 110 and a second buffer amount allocated to the corresponding ONU 120. [ That is, the amount of traffic that can not be transmitted through the band allocated to the specific ONU 120 by the OLT 110 is accumulated for a predetermined time for each specific ONU 120, and the SDN agent 111 accumulates the amount of traffic, If it is greater than the threshold value, it can be determined that the traffic congestion has occurred.

The second method is a method using a packet drop generated in the ONU 120 as in step 240. That is, when the amount of upstream traffic from a specific ONU 120 to the OLT 110 exceeds the buffer size of the ONU 120, a packet drop occurs in the buffer of the ONU 120. The ONU 120 calculates the amount of packet drop and delivers it to the OLT 110 through an OAM (Operation, Administration, Maintenance) message. The SDN agent 111 included in the OLT 110 accumulates It can be determined that traffic congestion has occurred when the amount of dropped packets is greater than a second threshold value.

At this time, when a traffic congestion occurs, the SDN agent 111 of the OLT 110 issues a Notification message for the traffic congestion event to the SDN controller 130. The notification message may include information on the ONU 120 in which the current traffic congestion has occurred and information on the traffic congestion amount.

Thereafter, the SDN controller 130 may check the available resources according to the notification message about the received traffic congestion event, and may generate a new SLA configuration and transmit the new SLA configuration to the SDN agent 111 of the OLT 110. The SDN agent 111 of the OLT 110 can solve the traffic congestion problem by controlling the bandwidth of the ONU 120 according to the new SLA configuration received in step 250. [

3 is a diagram illustrating an example of traffic congestion occurrence according to an SLA standard according to an embodiment of the present invention.

FIG. 3 shows an example of a situation where traffic congestion occurs according to the SLA standard in the embodiment of the traffic congestion solving system of the SDN-based PON as shown in FIG. Typical SLA criteria are Maximum Bandwidth (SLA_max) and Minimum Bandwidth (SLA_min: Minimum Bandwidth). However, depending on the implementation method, only one of the two minimum bandwidths or maximum bandwidths can be used. In the present invention, both embodiments are shown. In FIG. 3, the maximum bandwidth of each node is represented by a dotted line, and the minimum bandwidth is represented by a solid line. The thick solid line is an average of the average throughput of each node.

The minimum bandwidth (SLA_min) of the SLA is a guaranteed bandwidth of a specific node, which means a minimum guaranteed bandwidth to be guaranteed to the corresponding ONU even in the case where traffic of the network is dense. In this case, the sum of the minimum bandwidths of all the ONUs must be smaller than the total network capacity (C) of the PON system.

[Equation 1]

On the other hand, the maximum bandwidth of the SLA (SLA_max) means the maximum bandwidth that can be used by a specific node. When the bandwidth of the minimum bandwidth is available to other nodes, do.

Referring to FIG. 3, in the H node, the average transmission rate is smaller than the minimum bandwidth for most of the time, and the average transmission rate increases at the time t2. However, since the average transmission rate is smaller than the maximum bandwidth, traffic congestion does not occur unless traffic of other nodes is congested.

Similarly, at the B node, the average transmission rate is found to be below the minimum bandwidth for a given total time. Therefore, traffic congestion does not occur in the B-node.

On the other hand, the T-node can confirm that traffic congestion occurs at a certain point in time. The packet drop occurs in the buffer of the ONU 120 from the instant when the maximum bandwidth of the SLA is exceeded, and the traffic congestion occurs from the time t1 and the network congestion will be experienced. However, this traffic congestion is resolved after a certain period of time. As a result, the service quality is greatly deteriorated during the time when the traffic congestion occurs, thereby inconveniencing users.

4 is a diagram illustrating an SLA configuration setting procedure according to a traffic congestion event according to an embodiment of the present invention.

The present invention provides a method for resolving traffic congestion by changing the SDN-based PON system to a new SLA configuration dynamically according to network conditions and reflecting the new policy to the network.

At step 410, the SDN controller 130 may receive an event for traffic congestion from the SDN agent. For example, if traffic congestion is detected at time t1 of the T-node as shown in FIG. 3 (c), the SDN agent 110 may report the traffic congestion event to the SDN controller 130. [

In step 420, the SDN controller 130 may identify additional available network available resources for the node where the traffic congestion has occurred. At this time, the SDN controller 130 can determine whether or not the available network available resources (S) can be supported through the following Equation (2).

[Formula 2]

는 i번째 노드의 평균 전송률을 의미한다. 그리고, M은 전체 네트워크의 가용할 수 있는 최대 용량에 대한 임계치를 의미하며, M은 네트워크의 총 트래픽 가용 용량(C)보다 작아야 한다.

이때, SDN 제어 장치(130)는 전체 네트워크의 가용할 수 있는 최대 용량(M)에서 각 노드 평균 전송률의 합을 뺀 결과가 최소 변화량(

)가 보다 큰 경우 지원 가능한 네트워크의 가용 자원이 존재한다고 판단 할 수 있다. 여기서 최소 변화량(

)은 트래픽 폭주에 대한 새로운 SLA 구성 시 대역 설정을 위한 변화폭의 설정 단위를 의미하며 전체 네트워크 용량의 일정 퍼센티지(%)로 정의할 수 있다. From here

Denotes the average transmission rate of the i-th node. And M is a threshold value for the maximum available capacity of the entire network, and M should be smaller than the total available traffic capacity C of the network.

At this time, the SDN controller 130 determines whether the result obtained by subtracting the sum of the average transmission rates of the nodes from the maximum available capacity M of the entire network is the minimum variation

) Is larger, it can be determined that there is available resources of the supportable network. Here,

) Is a unit for setting the bandwidth for setting a new SLA for traffic congestion and can be defined as a certain percentage (%) of the total network capacity.

In step 430, the SDN controller 130 may store the current SLA configuration state if the existence (S) of existence of the available network usable resources is one. This process is necessary to restore the original SLA configuration in the future.

Thereafter, in step 440, the SDN controller 130 may adjust the bandwidth of the node where the traffic congestion has occurred to create a new SLA configuration. At this time, a new SLA configuration can be expressed by the following equation (3).

[Formula 3]

)만큼 변경하여 새로운 SLA 구성을 생성할 수 있다. 이때, 트래픽 대역폭 변화량은 최소 변화량(

)의 크기에 따라 빠르게 변화할 수 도 있고 느리게 변화할 수도 있다. 그리고 j는 트래픽 폭주로 인한 SLA 구성 설정에 대한 변경 번호로서 최초 설정인 0부터 시작하여 SLA 구성 설정이 변경될 때마다 증가한다.That is, the SDN controller 130 sets the maximum bandwidth of the kth node where the traffic congestion has occurred to the minimum variation (

) To create a new SLA configuration. At this time, the traffic bandwidth change amount is the minimum change amount

) May vary rapidly or may change slowly. And j is a change number for the SLA configuration due to traffic congestion, and increases every time the SLA configuration is changed, starting at 0, which is the initial setting.

If the SDN controller 130 determines in step 420 that the available network availability resource S is 0, the processing procedure for the traffic congestion is not available because there is no resource available in the current network none.

If the SDN controller 130 changes the SLA configuration setting due to the traffic congestion event as in steps 410 to 440, the following five situations may additionally occur. First, the first situation is that the traffic congestion problem for the node where the traffic congestion occurs is not resolved despite the new SLA configuration, and the traffic congestion event occurs again in the next event cycle in the same node. In this case, the problem of traffic congestion can be solved by performing steps 410 to 440 in accordance with the existence S of existence of the available network available resources, such as the situation where the previous traffic congestion has occurred.

5 is a diagram illustrating an SLA configuration setting procedure according to an event of traffic congestion resolution according to an embodiment of the present invention. Specifically, the second situation is when the traffic congestion is resolved at the node where the traffic congestion occurs.

If the traffic congestion has been resolved at the node where the traffic congestion has occurred, the SDN controller 130 may receive an event for traffic congestion resolution from the SDN agent 111 at step 510.

 The SDN agent 111 periodically observes the average transmission rate of the k-th node and determines whether or not the traffic congestion has been solved through the following Equation (4).

[Formula 4]

는 트래픽 폭주가 발생하여 새로운 SLA 구성 설정을 통해 대역폭이 변경된 k번째 노드의 평균 전송률을 의미한다. 이때, SDN 에이전트(111)는 대역폭이 변경된 k번째 노드의 평균 전송률이 기존 초기 설정된 최대 대역폭 보다 작아지면 트래픽 폭주가 해소된 것으로 판단할 수 있다. here

Means the average transmission rate of the kth node whose bandwidth has been changed through a new SLA configuration due to traffic congestion. At this time, the SDN agent 111 can determine that the traffic congestion has been resolved if the average transmission rate of the k-th node whose bandwidth is changed becomes smaller than the initially set maximum bandwidth.

Thereafter, in step 520, the SDN control device 130 may determine whether the SLA configuration for the node where the traffic congestion has occurred has changed.

If it is determined that the SLA configuration for the node experiencing the traffic congestion has changed, the SDN controller 130 may restore the current SLA configuration to the originally configured SLA configuration at step 530.

6 is a diagram illustrating an SLA configuration setting procedure according to an event of traffic overload according to an exemplary embodiment of the present invention. Specifically, the third situation is that the network capacity is exceeded due to a lack of available network resources in the SDN-based PON system while the SLA configuration change service for traffic congestion is being performed.

The SDN controller 130 may periodically monitor the network resources of the SDN-based PON system to determine whether to maintain the current configuration as shown in Equation 5 below.

[Formula 5]

Specifically, after the SLA configuration is changed due to traffic congestion, the SND agent 111 of the OLT 110 periodically checks the average transmission rate of the entire SDN nodes, and when the sum of the average transmission rates of the nodes becomes available to the entire network of the PON system Exceeding the maximum capacity (M) that can be exceeded causes an overflow event.

Accordingly, the SDN control device 130 may receive an event for the traffic capacity overload from the SDN agent 111, as in step 610. [ Thereafter, the SDN controller 130 determines whether the SLA configuration for the node experiencing the traffic overflow has changed, such as step 620. If it is determined that the SLA configuration for the node experiencing the traffic overflow has changed, The controller 130 may restore the current SLA configuration to the immediately preceding SLA configuration in step 630. [

[Formula 6]

However, if the current SLA configuration setting state is the initial setting (j = 0), the initial setting state will be maintained.

7 is a view illustrating an SLA configuration setting procedure according to a case where traffic congestion occurs consecutively in two nodes according to an embodiment of the present invention. Specifically, the fourth situation is a situation where a traffic congestion event occurs in another B node in a situation where a traffic congestion occurs in a specific A node and a configuration change is made to the A node. In addition, there is a situation where a traffic congestion occurs in addition to a new node in a situation where a change procedure due to traffic congestion has already been performed in one or more nodes.

Specifically, the SDN controller 130 may receive an event for traffic congestion for the A node from the SDN agent 111, as in step 710. [

The SDN controller 130 may then check for additional available network available resources for node A where traffic congestion has occurred. If there is additional supportable network available resources for node A where traffic congestion has occurred, SDN controller 130 generates a new SLA configuration that adjusts the bandwidth of node A as in step 720, The congestion phenomenon can be solved.

At this time, if traffic congestion has occurred in another B-node, the SDN controller 130 may receive a traffic congestion event for the B-node from the SDN agent 111 as in step 730. [

Then, the SDN controller 130 checks additional available network usable resources for the B node where the traffic congestion has occurred as in step 740, and if the identified network usable resources exist, Lt; RTI ID = 0.0 > SLA < / RTI > Then, the SDN controller 130 generates a new SLA configuration in which the bandwidth of the B node is adjusted as in step 760, so that the traffic congestion for the B node can be solved.

However, if the network resource is not available, not only the B node where the new traffic congestion occurred, but also all the nodes whose configuration has been changed due to A node that previously changed the SLA configuration setting or previous traffic congestion, It should be restored to the state of Equation (6).

However, if there is no network available resource identified in step 740, the SDN controller 130 does not change the SLA configuration on the B node. In this case, traffic congestion to the B node can not be resolved due to the cancellation of the congestion traffic of the previous node. Therefore, the SDN controller 130 restores the previous configuration to all the nodes that have undergone the traffic congestion as well as the A node as in step 770 and have changed the SLA configuration. Then, the SDN controller 130 can resolve the traffic congestion by inducing the resource re-competition for the nodes that can not solve the traffic congestion.

In the fifth situation, traffic congestion is simultaneously detected at a plurality of nodes. As in the fourth situation, if the resource is re-competing, traffic congestion may occur at more than one node at the next congestion detection time. As shown in FIG. 8, when a congestion event occurs in a plurality of nodes, first, it is checked whether or not network resources that can be supported by all of the plurality of nodes are available. At this time, the SDN controller 130 can determine the presence (S) of network usable resources that can be additionally supported for a plurality of nodes through Equation (7) below.

[Equation 7]

In Equation 7, an increment is added by the number (n) of nodes in which the congestion occurred in Equation 2. The SDN controller 130 may store the SLA configuration state of the current congested nodes and generate a new SLA configuration as shown in Equation (3) if the presence (S) of available network resources available is 1. However, when it is determined that the availability S of the available network-enabled resources is 0, the number n of Equation 7 is decremented by 1, and it is determined to which of the nodes additional bandwidth support is possible. In this way, the number of nodes that can be finally supported (S = 1) is found, and the average drop rate of the nodes experiencing congestion can be compared to support the additional bandwidth sequentially from the node with the greatest congestion.

Specifically, FIG. 8 shows a processing procedure for a situation where two nodes simultaneously run into congestion. First, in step 810, the SDN controller 130 may determine whether network resources for both nodes are available. If there is available network resources for both nodes, the SDN controller 130 stores the SLA configuration state for the two nodes in step 820 and the new SLA configuration for both nodes as in step 830 You can create and change it.

However, if there is no available network resource for both nodes, the SDN controller 130 calculates whether there is a network resource available for one node, as in step 840. [ If there is supportable network resource for one node, the SDN controller 130 may preferentially allocate the additional bandwidth by selecting a node having a higher packet drop rate among the two nodes as in step 850. The SDN controller 130 may then save the SLA configuration state of the selected node as in step 860 and create and modify a new SLA configuration for the selected node, such as step 860.

FIG. 9 is a diagram illustrating an exemplary SLA configuration change according to an exemplary embodiment of the present invention. Referring to FIG.

The SND controller 130 may receive the traffic congestion event from the SDN agent 111 at the time of the T-node t1 in the embodiment of solving the traffic congestion problem that the SDN controller 130 performs.

Then, the SDN controller 130 can reduce the traffic congestion to the T-node by increasing the maximum bandwidth (SLA_max) of the T-node by creating a new SLA configuration in which the bandwidth of the T-node experiencing the traffic congestion problem is adjusted.

If the SDN agent 111 generates an event for overflow due to an increase in traffic at another node H 2 at time t 2, the SDN controller 130 sets the SLA configuration of the T node to the previous SLA configuration Restore.

At time t3, the SDN agent 111 may generate a traffic congestion resolution event and notify the SDN controller 130 that the traffic congestion for the T-node has been resolved.

Meanwhile, the method according to the present invention may be embodied as a program that can be executed by a computer, and may be embodied as various recording media such as a magnetic storage medium, an optical reading medium, and a digital storage medium.

Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or combinations thereof. Implementations may be implemented in a computer program product, such as an information carrier, e.g., a machine readable storage device, such as a computer readable storage medium, for example, for processing by a data processing apparatus, Apparatus (computer readable medium) or as a computer program tangibly embodied in a propagation signal. A computer program, such as the computer program (s) described above, may be written in any form of programming language, including compiled or interpreted languages, and may be stored as a stand-alone program or in a module, component, subroutine, As other units suitable for use in the present invention. A computer program may be deployed to be processed on one computer or multiple computers at one site or distributed across multiple sites and interconnected by a communications network.

Processors suitable for processing a computer program include, by way of example, both general purpose and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer may include one or more mass storage devices for storing data, such as magnetic, magneto-optical disks, or optical disks, or may receive data from them, transmit data to them, . ≪ / RTI > Information carriers suitable for embodying computer program instructions and data include, for example, semiconductor memory devices, for example, magnetic media such as hard disks, floppy disks and magnetic tape, compact disk read only memory A magneto-optical medium such as a floppy disk, an optical disk such as a DVD (Digital Video Disk), a ROM (Read Only Memory), a RAM , Random Access Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), and the like. The processor and memory may be supplemented or included by special purpose logic circuitry.

In addition, the computer-readable medium can be any available media that can be accessed by a computer, and can include both computer storage media and transmission media.

While the specification contains a number of specific implementation details, it should be understood that they are not to be construed as limitations on the scope of any invention or claim, but rather on the description of features that may be specific to a particular embodiment of a particular invention Should be understood. Certain features described herein in the context of separate embodiments may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments, either individually or in any suitable subcombination. Further, although the features may operate in a particular combination and may be initially described as so claimed, one or more features from the claimed combination may in some cases be excluded from the combination, Or a variant of a subcombination.

Likewise, although the operations are depicted in the drawings in a particular order, it should be understood that such operations must be performed in that particular order or sequential order shown to achieve the desired result, or that all illustrated operations should be performed. In certain cases, multitasking and parallel processing may be advantageous. Also, the separation of the various device components of the above-described embodiments should not be understood as requiring such separation in all embodiments, and the described program components and devices will generally be integrated together into a single software product or packaged into multiple software products It should be understood.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to 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.

110: Optical Line Terminal (OLT)
111: SDN agent
120: Optical Network Units (ONU)
130: SDN control device

Claims (16)

A traffic congestion resolution method performed by an SDN agent to solve a traffic congestion problem of a plurality of passive optical networks (PONs) linked through a software defined network (SDN)
Monitoring the transmission status of uplink traffic of the PON in real time to determine whether the traffic is congested for a specific node;
Transmitting an event for the traffic congestion to the SDN controller if it is determined that traffic congestion has occurred for the particular node;
Changing the configuration of the PON according to a control signal received from an SDN control device to resolve the traffic congestion
/ RTI > The method according to claim 1,
Wherein the determining step comprises:
A first buffer amount of the optical network units received through a buffer status report (BSR) of a plurality of optical network units (ONUs) interworking with the PON and a first buffer amount of the optical network units 2 checking the buffer amount;
Calculating a difference between the first buffer amount and the second buffer amount and accumulating the difference for each ONU for a predetermined time;
Determining that traffic congestion has occurred when the difference between the first buffer amount and the second buffer amount accumulated for each ONU is greater than a preset first threshold value
/ RTI > The method according to claim 1,
Wherein the determining step comprises:
Collecting an amount of packet drop generated for each of a plurality of ONUs connected to the PON; And
Determining that traffic congestion has occurred when the amount of the collected packet drop is greater than a second predetermined threshold value for a predetermined period of time
Lt; / RTI >
Wherein the packet drop comprises:
And if the amount of uplink traffic of the ONU exceeds the buffer size of the corresponding ONU, the traffic congestion occurs in the buffer. The method according to claim 1,
Monitoring the transmission status of the PON upstream traffic in real time to determine whether traffic congestion for a specific node is eliminated; And
If it is determined that the traffic congestion for the specific node has been solved, transmitting an event for the traffic congestion resolution to the SDN control device
Further comprising the step of: A traffic congestion resolution method performed by an SDN control device to solve a traffic congestion problem of a plurality of passive optical networks (PONs) interworked through a software defined network (SDN)
Receiving an event for traffic congestion from an SDN agent;
Confirming available resources available for the node where the traffic congestion has occurred;
Changing a service level agreement (SLA) configuration according to whether the identified available resource exists; And
Transmitting the modified SLA configuration to the SDN agent
/ RTI > 6. The method of claim 5,
Wherein the verifying step comprises:
And checking the available resources by using the total traffic available capacity of the plurality of PONs linked through the SDN and the average transmission rate of each node. 6. The method of claim 5,
Wherein the modifying comprises:
Storing the current SLA configuration if the identified available resources exist;
Adjusting a bandwidth of the node where the traffic congestion has occurred to generate a new SLA configuration
Lt; / RTI >
Wherein the generating comprises:
And changing a maximum bandwidth of the node where the traffic congestion has occurred by a preset minimum change amount. 6. The method of claim 5,
Receiving an event for traffic congestion resolution from the SDN agent;
Determining whether the SLA configuration for the node where the traffic congestion has occurred is changed if an event for the traffic congestion dissolution is received; And
If it is determined that the SLA configuration for the node where the traffic congestion has occurred is changed, restoration to the previous SLA configuration
/ RTI > An SDN agent for solving a traffic congestion problem of a plurality of passive optical networks (PONs) linked through a software defined network (SDN)
A determiner for monitoring the transmission status of uplink traffic of the PON in real time to determine whether traffic is congested for a specific node;
A transmitting unit for transmitting an event for the traffic congestion to the SDN control apparatus when it is determined that traffic congestion has occurred for the specific node; And
And for changing the configuration of the PON according to a control signal received from the SDN control apparatus to solve the traffic congestion,
And a traffic congestion solving apparatus. 10. The method of claim 9,
Wherein,
A first buffer amount of the optical network units received through a buffer status report (BSR) of a plurality of optical network units (ONUs) interworking with the PON and a first buffer amount of the optical network units 2 buffer, calculates a difference between the first buffer amount and the second buffer amount, and accumulates the difference between the first buffer amount and the second buffer amount for each ONU for a predetermined period of time, And determines that a traffic congestion has occurred if the first threshold value is greater than the first threshold value. 10. The method of claim 9,
Wherein,
Collects an amount of a packet drop generated for each of the plurality of ONUs connected to the PON and determines that traffic congestion occurs when the amount of the collected packet drop is greater than a predetermined second threshold value for a predetermined time,
Wherein the packet drop comprises:
And a traffic congestion occurring in the buffer when an upstream traffic transmission amount of the ONU exceeds a buffer size of the corresponding ONU. 10. The method of claim 9,
Wherein,
Monitoring the transmission status of the uplink traffic of the PON in real time to determine whether to resolve the traffic congestion for a specific node,
Wherein the transmission unit comprises:
And transmits an event for the traffic congestion resolution to the SDN control apparatus when it is determined that the traffic congestion for the specific node has been solved. An SDN control apparatus for solving a traffic congestion problem of a plurality of passive optical networks (PONs) linked through software defined networks (SDN)
A receiving unit for receiving an event for traffic congestion from an SDN agent;
A confirmation unit for confirming available resources available for the node where the traffic congestion has occurred;
A change unit configured to change a service level agreement (SLA) configuration according to existence of the identified available resources; And
And transmitting the changed SLA configuration to the SDN agent.
And a traffic congestion solving apparatus. 14. The method of claim 13,
The checking unit,
And verifies the available resources by using the total traffic available capacity of the plurality of PONs linked through the SDN and the average transmission rate of each node. 14. The method of claim 13,
The changing unit may change,
Storing the current SLA configuration and adjusting a bandwidth of the node where the traffic congestion occurs to generate a new SLA configuration if the identified available resources exist,
Wherein the generation unit comprises:
And changes the maximum bandwidth of the node where the traffic congestion has occurred by a preset minimum change amount. 14. The method of claim 13,
The receiver may further comprise:
Receive an event for traffic congestion resolution from the SDN agent,
The checking unit,
When the event for the traffic congestion is received, checking whether the SLA configuration for the node where the traffic congestion has occurred is changed,
The changing unit may change,
And restores the SLA configuration to a previous SLA configuration if it is determined that the SLA configuration for the node where the traffic congestion has occurred is changed.

Images