RU2822214C2 - Method for early diagnosis of real-time traffic loss with control of timeouts in software-defined networks - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to telecommunications. Method implements heterogeneous traffic transmission in a network, in which there are multiple network devices, such as a controller and switches operating on the OpenFlow protocol, which provide for real-time traffic between nodes and elastic traffic, traffic frames have different header fields, wherein the real-time traffic frames in the header contain an indicator of the frame sending time, elastic traffic is transmitted in a standard manner via the OpenFlow protocol in switches; for real-time traffic frames, timeouts are monitored for compliance with the time of frame arrival in the network with a pre-known time window for the possibility of transmitting the frame further via the OpenFlow protocol and determining a route in the network.

EFFECT: enabling early diagnosis of real-time traffic loss before switching to OpenFlow switch flow tables.

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Description

The invention relates to the field of telecommunications and can be used in a software-defined network (SDN) and switches based on the OpenFlow protocol for transmitting heterogeneous traffic.

State of the art

Modern networked computer paradigms are based on Ethernet technology, which allows various traffic to be transmitted over the network. Existing requirements for traffic processing must have the properties of mobility, speed, and simplified administration of network equipment. All these requirements led to the emergence of PKS [US 9215093 B2].

The main element is the controller, which processes traffic and calculates optimal routes for transmitting traffic to switches. Traffic is exchanged via the OpenFlow protocol [US 9215093 B2].

In the PCS, control and configuration occurs over data streams and a set of frames. An incoming frame enters a switch running using the OpenFlow protocol, where a match between a set of frame fields is found in one of the flow tables. The flow table consists of the following fields: IEEE 802.1 fields, priority, counters, instructions, timeouts [US 9215093 B2]. As in a regular network, heterogeneous traffic is transmitted, which in turn is divided into real-time traffic and regular (elastic) traffic.

In the known communication method [US 9356871 B2], the SCN and the controller react to a possible loss of real-time traffic too late. The disadvantage of this method is that it takes some processing time to transmit a frame from the controller to the OpenFlow switch, since the frame is not transmitted instantly. In the known existing method [US 2018/0063848 A1], a rule for an incoming frame is searched in the flow tables for some correspondence to the list of frame header fields; if the frame does not have a rule in the first flow table, it moves to the next table, and so on. The disadvantage of this method is that the frame can only be deleted at the stage of searching for a rule in the last flow table. The OpenFlow protocol algorithm in the known existing method [US 9215093 B2] spends significant time searching for a rule in the flow tables for an incoming frame. The disadvantages of this method include late informing the controller about deleting the frame, until all flow tables have been searched, in case of a mismatch in the fields; The flow table is too cumbersome; the table could be simplified by controlling timeouts at the input of the OpenFlow switch.

The closest technical solution is patent US 9215093 B2 “ENCOOING PACKETS FOR TRANSPORT OVER SDN NETWORKS” (prototype). Analogs: US 9356871 B2 “PROGRAMMABLE MANAGEMENT ENGINE FOR NETWORKS”, US 2018/0063848 A1 “USING LTE CONTROL CHANNEL TO SEND OPENFLOW MESSAGE DIRECTLY TO SMALL CELLS TO REDUCE LATENCY IN AN SDN-BASED MULTI-HOP WIRELESS BACKHAUL NETWORK.”

Technical result

The technical result is early diagnosis of real-time traffic losses before moving to the OpenFlow switch flow tables by monitoring timeouts at the switch input.

Brief description of drawings

In fig. Figure 1 shows a diagram of the functioning algorithm of the method for early diagnosis of real-time traffic losses with control of timeouts in the SDN.

In fig. Figure 2 shows the preferred option for the operation of switch nodes using the OpenFlow protocol, transmitting heterogeneous traffic, where 1 is the bus for receiving frames from the frame forwarding equipment to the input port of the switch; 2 – traffic classifier; 3 – bus for real-time traffic; 4 – bus for normal traffic; 5 – timeout control defender; 6 – flow table 0; 7 – flow table 1; 8 – flow table N; 9 – group table; 10 – OpenFlow command decoder; 11 – output channel bus and further frame transmission.

Figure 3 shows a possible version of a hardware defender in the PKS and consists of several timeout control blocks: control for instantaneous removal of a frame from the PKS hard timeout and control depending on the length of the frame for reaching the receiving side idle timeout.

In fig. Figure 4 shows the timing diagrams of the operation of the switch using the OpenFlow protocol in the PCN using the proposed method when transmitting heterogeneous traffic: RT - real-time traffic and ET - regular (elastic) traffic. In case of unsuccessful passage of the first control frame of the hard timeout check, after time t1 the PKS controller is informed about retransmission, while checking the second stage of the idle timeout timeout immediately after time t2. The usual method of transmitting traffic to the PCN and controlling losses of RF traffic occurs at a minimum only after time t3 when comparing with the rules in the flow table 0, and in the maximum case only after time N*t4, until a comparison occurs with all flow tables N and only after This causes a message about deleting the PB frame to the PKS controller.

Detailed Description of the Invention

The implementation of the algorithm for the functioning of the proposed method for early diagnosis of real-time traffic losses with control of timeouts in the PCN consists of performing the following actions:

1. A frame from the PKS controller arrives at the incoming port of the switch operating using the OpenFlow protocol.

2. The frame received by the switch is classified by the type of traffic (real-time traffic or elastic traffic).

3. Elastic traffic is processed by the existing transmission method and forwarded to the switch flow tables to find a rule for a given frame and further route it.

4. In the case of real-time traffic, it goes to the input of the timeout control defender, which consists of two check blocks: hard timeout and idle timeout.

5. If the arrival time of a real-time traffic frame is greater than the previously known hard timeout timeout window, then a command is issued to inform the controller to retransmit the frame and remove the current frame from the network.

6. If the arrival time of the real-time traffic frame is less than or equal to the previously known hard timeout timeout window, the following defender check is performed with idle timeout control.

7. If the arrival time of a real-time traffic frame is greater than the previously known idle timeout timeout window taking into account the frame length, then a command is issued to inform the controller to retransmit the frame and remove the current frame from the network.

8. If the arrival time of a real-time traffic frame is less than or equal to a previously known idle timeout timeout window based on the frame length, then a rule search is performed in the switch flow tables to determine further routing of the frame.

9. According to the found rule from the flow table, the command decoder executes the command for execution depending on its format and the command itself according to the found rule, and assumes the following action: transfer the frame to the output port of the switch, transfer the frame to the switch queue depending on its type, delete frame and inform the controller about retransmission.

10. Go to step 1 and transfer traffic to the SDN again.

The operation of the preferred option for the operation of switch nodes using the OpenFlow protocol, which transmits heterogeneous traffic, is as follows.

Bus 1 carries frames from the frame forwarding equipment to the input port of the switch. Traffic classifier 2 determines the type of traffic and its further processing. If the type of traffic is normal, then it is sent via bus 4 of this traffic, but if it is real-time traffic, then it is sent via bus 3.

The real-time traffic frame is sent to the hardware defender 5 in the PKS, which consists of several timeout control blocks: control for instant removal of the frame from the PKS and control depending on the length of the frame reaching the receiving side.

If the timeout control is successfully passed, the real-time traffic frame is sent to search for a rule for this frame in one of the flow tables (6-8); the rule search is also determined for the regular traffic frame. Switching between flow tables and their relationships is ensured by group table 9 of the switch using the OpenFlow protocol.

According to the rule found from the flow table, the command decoder 10 executes the command for execution depending on its format and the following is performed: either transfer the frame to the output channel bus of the switch 11, or transfer the frame to the switch queue depending on its type, or delete the frame and inform the controller about retransmission.

The functioning of the timing diagrams of the preferred device that implements the switch using the OpenFlow protocol in the PCN using the proposed method when transmitting heterogeneous traffic is as follows.

The current arrival time of the real-time traffic frame is compared with the previously known time window of each timeout (hard timeout, idle timeout), and:

1) if both times are equal, then the real-time traffic frame is transmitted immediately to the output channel of the switch;

2) if the arrival time of the real-time traffic frame is greater than any pre-known time window, then a command is issued to inform the controller to retransmit the frame at an early stage;

3) if the arrival time of a real-time traffic frame is less than the previously known hard timeout timeout window, the following check is performed with the idle timeout timeout window, and if the arrival time in this case is also less than the idle timeout timeout timeout window, then transmission to the switch queue for traffic frames real time.

Claims (7)

1. A method for early diagnosis of real-time traffic losses with control of timeouts in a software-defined network (SDN), which implements the transmission of heterogeneous traffic, in which there are many network devices, such as a controller and switches operating using the OpenFlow protocol, which provide traffic forwarding between nodes real-time and elastic traffic, traffic frames have different header fields, and real-time traffic frames in the header contain a pointer to the time the frame was sent, elastic traffic is transmitted in a standard way via the OpenFlow protocol in switches, characterized in that timeouts are monitored for real-time traffic frames to match the time of arrival of the frame to the network with a pre-known time window for the possibility of transmitting the frame further via the OpenFlow protocol and determining the route in the network; real-time traffic comes from the input ports of the switch and is sent via the bus to the input of the switch timeout control defender to control checks for instant removal of a frame from the PCN using the hard timeout and deletion depending on the length of the frame reaching the receiving side using the idle timeout; for real-time traffic, control for instant removal of a frame from the SCN consists of comparing the frame arrival time with a pre-known time window of the hard timeout timeout; if the frame arrival time does not fit into the time window, the frame is removed from the SCN and is reported to the controller through a set of OpenFlow protocol instructions PKS; for real-time traffic, control depending on the frame length of reaching the receiving side consists of comparing the frame arrival time with a pre-known idle timeout timeout window; if the frame arrival time does not fit into the time window, the frame is removed from the SCN and through a set of OpenFlow protocol instructions reported to the PKS controller. 2. The method according to claim 1, characterized in that control for instant removal of a frame from the SCN is performed after transmitting a real-time traffic frame to the input port of the switch and before transmitting the frame to the flow tables. 3. The method according to claim 1, characterized in that control depending on the frame length of reaching the receiving side is performed after successful control for instantaneous removal of the frame from the SDN and before transmitting the frame to the flow tables. 4. The method according to claim 1, characterized in that for real-time traffic the arrival time of the frame is compared with the pre-known time window of switch defender timeouts; if the frame arrival time does not fit into the time window of any of the timeouts, the frame is removed from the SCS and after a set of OpenFlow protocol instructions is communicated to the PKS controller. 5. The method according to claim 1, characterized in that the flow tables in OpenFlow for real-time traffic are simplified by monitoring and storing timeouts in its structure and the performance of frame transmission analysis is increased by removing control of timeouts in the flow tables. 6. The method according to claim 1, characterized in that the type of traffic at the SDN input is determined before the start of transmission in the flow tables of the OpenFlow protocol. 7. The method according to claim 1, characterized in that a hardware defender unit is introduced into the PCS, which performs the functions of timeout control.

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