RU2544741C1 - METHOD FOR AUTOMATIC CONFIGURATION OF OpenFlow SWITCHES AND OpenFlow ROUTERS - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: method for automatic configuration of OpenFlow switches and OpenFlow routers comprises modifying network traffic tables of OpenFlow equipment. A network packet is forwarded to the controller of a software-configurable network with an included module for determining the write priority in the network traffic table, wherein the set of quality parameters of the network traffic is determined using parameters which correspond to a class of traffic with which said packet is associated, and the priority of the packet specified by the first three bits of the ToS byte; if the ToS byte is not specified in the network packet, the entry corresponding to the network packet in the network traffic table is assigned the lowest priority; if the ToS byte is specified in the network packet, the packet is associated with one of three traffic classes, and the packet is then assigned a write priority in the network traffic table, calculation of which is carried out based on a weight coefficient and an OpenFlow statistics parameter corresponding to a selected traffic class, and also based on the packet priority specified by the first three bits of the ToS byte; the controller of the software-configurable network, in accordance with the OpenFlow protocol, then generates an instruction to add a new entry into the network traffic table of the OpenFlow switch or OpenFlow router.

EFFECT: faster operation of OpenFlow switches and OpenFlow routers when processing network packets.

2 dwg

Description

The invention relates to the field of automation control OpenFlow compatible switches and routers that make up the network infrastructure of software-configurable networks, based on the dynamic change of priorities of the entries in the flow tables on the network equipment in accordance with the traffic class, determined on the basis of the transmission quality parameters of network packets.

In connection with the development of computer networks, the task of creating a new approach to managing network equipment is being updated. Currently, the technology of software-configurable networks is actively developing, which is based on the separation of the functions of managing the network infrastructure and the functions of actually transmitting data over the network. Management functions are implemented in a dedicated component of a software-configured network — in a controller of a software-configured network, which is a server computer that controls network OpenFlow compatible equipment using the OpenFlow protocol.

Currently used methods for managing network equipment implement the method of remotely controlling network equipment according to the “manual” principle and do not have sufficient flexibility and speed to provide expansion (scaling) of the network and uniform distribution of network load in large networks with complex topology, which include software configurable networks. The traditional configuration of each network device is performed by a person (system administrator, network administrator or network equipment operator) using command or file management protocols SNMP, Telnet, SSH, FTP. The architecture of the software-configurable networks is based on a different approach based on the use of the OpenFlow open protocol, which allows you to programmatically control the network architecture, not "manually". The OpenFlow protocol allows you to configure network devices programmatically from a centralized network management component — a software-configured network controller. The main functions of a software-configurable network controller are adding and deleting entries from the network flow table on a controlled network device connected to the controller and compatible with the OpenFlow protocol. In this case, the controller provides a dynamic analysis of the current state of all connected devices. A network operating system is installed on the controller of the software-configurable network, which ensures the operation of the network management software system. The tasks of such a network management system include: collecting information about network equipment, collecting data about network interactions of network equipment and the current status of network equipment, setting up network equipment depending on the level of network load and current status.

In software-configured networks, network devices (switches and routers) controlled by the OpenFlow protocol are called OpenFlow switches and OpenFlow routers. For each incoming network packet, the OpenFlow switch (OpenFlow router) decides on the direction of its further forwarding. The packet forwarding direction is determined based on the network flow control table. Each table in a network device that supports the OpenFlow protocol and connects to the controller consists of a set of records. Each entry contains the identification parameters of network packets for which this record is applied, statistical information and a set of instructions that should be applied to network packets. The route determination for each incoming network packet is carried out by comparing the parameters of this network packet with the parameters specified in each record of the network flow table stored on the OpenFlow switch and OpenFlow router. If a match is found, the network packet is processed according to the instructions specified in the corresponding record, and as a result, it is sent along the route specified in the instructions. If no record for this packet is found in the network flow table, then the packet is transmitted for processing to the controller of the software-configured network, which creates a new record for this network stream, namely this network packet and for all subsequent network packets of the same type, entering a new route for this network stream to the network stream table of the corresponding OpenFlow switch and OpenFlow router.

The software-configurable network controller configures OpenFlow switches and OpenFlow routers by changing entries in the network flow tables, thereby changing the direction of packet transmission on the network. In all existing OpenFIow equipment configurations, network flow tables are defined with entries for which the same priorities are specified. As a result, the entries in the table are arranged in random order. In existing solutions for managing OpenFlow switches and OpenFlow routers, all entries in the network flow tables are equal and their processing order is not specified in the table, which leads to the need to iterate over all entries in the network flow table in search of the desired entry and, accordingly, to temporary delays in the transmission of network packets (US 2011286324, H04L 12/26, publ. 2011-11-24; EP 2408155, H04L 12/56, publ. 2012-01-18).

However, OpenFlow-equipment allows you to set recording priorities and thereby control the sequence of processing network packets with this device. Thus, improving the performance of OpenFlow switches and OpenFlow routers when processing network packets consists in creating such a control system in software-configurable networks, which is based on reconfiguring the network flow tables based on calculating the priority of entries in the tables. This priority calculation is based on the partitioning of the ToS byte of a network packet into a set of classification pointers for this packet and distribution of network traffic among programmable classes of network packets.

The basis of the invention is the creation of a method for automatically configuring OpenFlow switches and OpenFlow routers, which improves the performance of OpenFlow switches and OpenFlow routers when processing network packets by implementing the management of network infrastructure in a computer programmable network, the infrastructure of which is OpenFlow switch (OpenFlow router) and controller software-defined network. The solution to this problem is provided by dynamically changing the priorities of the entries in the network flow tables in accordance with the parameters of network traffic quality and statistics of OpenFlow equipment. This method allows you to optimize the processing of a network packet by establishing the priority order of matching the packet parameters with the record parameters in the network stream table and further performing the steps indicated in the network stream table for the corresponding recording packet. By organizing recording queues based on priorities and classifying network packets, the use of this method reduces the time it takes to search for records in network flow tables and, as a result, increases the performance of network OpenFlow compatible network equipment.

The solution of the technical problem is ensured by transmitting a network packet for which no correspondence was found with entries in the network flow table of OpenFlow switches and OpenFlow routers, to the controller of a software-configured network to form a new record in the network flow table. This network stream table entry corresponding to this network packet is formed depending on whether the ToS byte is set. The first three bits of the ToS byte correspond to the priority of this IP packet, the fourth bit corresponds to the requirement for the delay time for transmitting the IP packet, the fifth bit corresponds to the bandwidth requirement for the route on which the IP packet should be transmitted, and the sixth bit corresponds to the reliability requirement for IP transmission package. If the ToS byte is not specified, the network packet is assigned the lowest write priority in the network stream table. A packet for which a ToS byte is specified refers to one of three classes of traffic. Next, this packet is assigned the priority of the entry in the network flow table, which is calculated taking into account the weight coefficient and the parameter of Open Flow statistics corresponding to the selected traffic class, as well as taking into account the priority of the packet specified by the first three bits of the ToS byte.

In accordance with the structure of the ToS byte, three classes (K _j , 1≤j≤3) of the processed network traffic are allocated, each of which is characterized by the center of the class (µ _j , 1≤j≤3):

- traffic, to which there are special requirements for the transmission delay (D-traffic, from the English Delay). The center of the class is the vector µ ₁ = 〈00010000〉;

- traffic, which has special requirements for the throughput of the route (T-traffic, from the English Throughput). The center of the class is the vector µ ₂ = 〈00001000〉;

- traffic, to which special requirements are placed on the reliability of transmission (R-traffic, from the English Reliability). The center of the class is the vector µ ₃ = 〈00000100〉.

Each class is initially assigned a weight coefficient value (w _j , 1≤j≤3), which affects the priority of the entry in the network flow table created in accordance with the analyzed network packet.

Each traffic class is assigned an Open Flow statistic parameter for the port (S _j , 1≤j≤3), which will be taken into account when calculating the recording priority in the network stream table:

- for D-traffic, the ratio of the number of sent packets (TransmPack) to the number of received packets (RecPack) is taken into account;

- for T-traffic, the ratio of the number of bytes sent (TransmBytes) to the number of received bytes (RecBytes) is taken into account;

- for R-traffic, the ratio of the number of packets dropped when receiving packets (RecDrops) and the number of packets dropped when receiving packets (TransmDrops) to the number of packets received (RecPack) is taken into account.

Figure 1 presents a diagram of the management of network flows in software-configured networks. The interaction between the OpenFlow switch (OpenFlow router) and the controller of the software-configured network is carried out using the OpenFlow protocol. For the network packet arriving at the network equipment, a record is searched in the network stream table. If the record is found, the packet is transmitted further to the network according to the instructions specified in this record. If there is no entry in the table of network streams corresponding to the network packet, this packet is transmitted to the controller of the software-configured network to generate a new record in the table of network streams. Figure 2 presents the operation diagram of the controller software-configured network. The packet arrives at the input to the controller for which there is no correspondence with the entries in the network flows table of the network equipment; at the output, the controller generates a new entry in the flows network table that contains parameters, statistics and instructions, and also sets the priority of this entry in the flows network table. When calculating the priority of a record in the table of network flows, the controller of the software-configured network takes into account the type of traffic to which the network packet received by the controller belongs and the priority of this network packet specified by the first three bits of the ToS byte, if the ToS byte is not specified, the network packet is assigned The lowest write priority in the network stream table.

To assign the network packet received by the controller of the software-configured network to one of the defined traffic classes, the Hamming distance is calculated [Sklyar B. Digital communication: Theoretical foundations and practical application. M .: Williams, 2003] between the center vector of the corresponding class and the vector representing the ToS byte of the packet being analyzed.

, где L - длина вектора.The Hamming weight of a binary vector is defined as the number of nonzero elements of this vector. Hamming distance - the number of positions at which the corresponding value vectors differ: $$d_{ij}={\Sigma }_{k=\mathrm{one}}^L\left|x_{i_k}-x_{j_k}\right|$$

where L is the length of the vector.

According to the properties of addition modulo 2, the sum of two binary vectors is another binary vector, the binary units of which are located at those positions by which these vectors differ.

The Hamming distance between two vectors is equal to the weighting Hamming coefficient of their sum. Also, the Hamming weight of a binary vector is equal to its Hamming distance to the zero vector. The Hamming distance is a metric on the set of binary vectors of length L, satisfying the axioms of the metric.

. Между полученным вектором $$x_i^{*}$$

и текущими центрами классов вычисляется расстояние Хэмминга: $$d_{ij}={\Sigma }_{k=1}^8\left|x_i^{*}{}_k-{\mu }_{j_k}\right|$$

, 1≤j≤3. Вектор $$x_i^{*}$$

относят к классу, которому соответствует наименьшее расстояние Хэмминга min_1≤j≤3 d_ij. Если для нескольких j выполняется равенство $$d_{ij}=\underset{1\le j\le 3}{\min }{d}_{ij}$$

, то вектор $$x_i^{*}$$

может быть отнесен к любому классу K_j, для которого $$d_{ij}=\underset{1\le j\le 3}{\min }{d}_{ij}$$

.The analyzed ToS byte of the network packet received by the software-configured network controller is represented as a vector $$x_i^{*}$$

. Between the resulting vector $$x_i^{*}$$

and the current class centers compute the Hamming distance: $$d_{ij}={\Sigma }_{k=\mathrm{one}}^8\left|x_i^{*}{}_k-{\mu }_{j_k}\right|$$

, 1≤j≤3. Vector $$x_i^{*}$$

relate to the class, which corresponds to the least Hamming distance min _1≤j≤3 d _ij . If for several j the equality $$d_{ij}=\underset{\mathrm{one}\le j\le 3}{\min }{d}_{ij}$$

then vector $$x_i^{*}$$

can be assigned to any class K _j for which $$d_{ij}=\underset{\mathrm{one}\le j\le 3}{\min }{d}_{ij}$$

.

к классу K_j вычисляется значение приоритета записи в таблице сетевых потоков, соответствующей сетевому пакета, полученному контроллером программно-конфигурируемой сети: F=w_j·S_j+P_i, где w_j - весовой коэффициент, соответствующий классу K_j, S_j - учитываемый параметр OpenFlow-статистики для порта, соответствующий классу K_j, P_i - приоритет, заданный первыми тремя битами байта ToS, указанный в десятичной системе счисления.In accordance with the established accessory of the vector $$x_i^{*}$$

to the class K _j , the value of the recording priority in the table of network flows corresponding to the network packet received by the controller of the software-configured network is calculated: F = w _j · S _j + P _i , where w _j is the weight coefficient corresponding to the class K _j , S _j - the taken into account parameter of OpenFlow statistics for the port corresponding to the class K _j , P _i is the priority specified by the first three bits of the ToS byte specified in the decimal system.

This method is universal due to the fact that for each interaction system in software-configurable networks, the infrastructure of which includes OpenFlow switches and OpenFlow routers, their own weight coefficients w _j , 1≤j≤3 can be determined.

.Consider an example of calculating the priority of an entry in the network flow table of an OpenFlow switch (OpenFlow router) corresponding to a network packet received by a software-configured network controller with a given ToS byte that corresponds to a binary vector $$x_0^{*}=〈10110100〉$$

.

и текущими центрами классов $$d_{0j}={\Sigma }_{k=1}^8\left|x_0^{*}{}_k-{\mu }_{j_k}\right|$$

, 1≤j≤3:We calculate the Hamming distance between the vector $$x_0^{*}$$

and current class centers $$d_{0j}={\Sigma }_{k=\mathrm{one}}^8\left|x_0^{*}{}_k-{\mu }_{j_k}\right|$$

, 1≤j≤3:

; $$d_{01}={\displaystyle \sum _{k=\mathrm{one}}^8\left|x_0^{*}{}_k-{\mu }_{{\mathrm{one}}_k}\right|}=3$$

;

; $$d_{02}={\displaystyle \sum _{k=\mathrm{one}}^8\left|x_0^{*}{}_k-{\mu }_{2_k}\right|}=5$$

;

. $$d_{03}={\displaystyle \sum _{k=\mathrm{one}}^8\left|x_0^{*}{}_k-{\mu }_{3_k}\right|}=3$$

.

и центрами классов:Determine the smallest value of the Hamming distance between the vector $$x_0^{*}$$

and class centers:

. $$\underset{\mathrm{one}\le j\le 3}{\min }{d}_{0j}=\min \left\{3;5;3\right\}=3=d_{01}=d_{03}$$

.

может быть отнесен как к классу K₁, так и к классу K₃. Отнесем вектор $$x_0^{*}=\langle 10110100\rangle$$

к классу K₁ с центром µ₁=〈00010000〉.Since for j = 1 and j = 3 is satisfied equation d _0j = min _1≤j≤3 d _0j, then in accordance with the proposed algorithm, the vector $$x_0^{*}$$

can be assigned to both class K ₁ and class K ₃ . Take the vector $$x_0^{*}=〈10110100〉$$

to class K ₁ with center µ ₁ = 〈00010000〉.

Suppose that the following weights w _j are assigned that correspond to the classes K _j , _{1 j j} 3 3: w ₁ = 20; w ₂ = 15; w ₃ = 30.

According to the proposed algorithm, class K ₁ corresponds to D-traffic, for which it is necessary to calculate the following parameter of OpenFlow statistics for the port:

, $$S_{\mathrm{one}}=\frac{TransmPack}{\mathrm{Re}cPack}$$

,

where TransmPack is the number of packets sent, RecPack is the number of packets received.

.Let TransmPack = 90, RecPack = 100. Then $$S_{\mathrm{one}}=\frac{90}{\mathrm{one\; hundred}}=0,9$$

.

The priority specified by the first three bits of the ToS byte specified in the decimal system is P ₀ = 5.

We calculate the priority of the entry in the network flow table that advises the network packet in question:

F = w ₁ · S ₁ + P ₀ = 20 · 0.9 + 5 = 23.

All network flows to which entries with a higher priority correspond in the network flow table will be processed earlier. Prioritizing entries in the network flow table of an OpenFlow switch (Open Flow router) and, accordingly, network flows reduces the detection time of entries in the network flow table by setting the order of entries.

The described method provides an increase in the performance of OpenFlow switches and OpenFlow routers in a software-configurable network, an increase in the throughput of a software-configurable network, a simplification of the traffic classification process, and a reduction in the number of errors when configuring a software-configurable network.

Claims (1)

A method for automatically configuring OpenFlow switches and OpenFlow routers, including changing the network flow tables of OpenFlow equipment, characterized in that the network packet is sent to the controller of the software-configured network with the recording priority determination module enabled in the network flow table, in which a set of parameters is determined the quality of network traffic using the parameters corresponding to the class of traffic to which this packet belongs and the priority of the packet specified by the first three bits mi of ToS bytes; if the ToS byte is not specified in the network packet, the lowest priority is assigned to the record corresponding to the network packet in the network stream table; if the ToS byte in the network packet is specified, the packet is assigned to one of three traffic classes, then this packet is assigned the priority of the entry in the network flow table, which is calculated taking into account the weight coefficient and the OpenFlow statistics parameter corresponding to the selected traffic class, as well as priority of the packet specified by the first three bits of the ToS byte; then, in the controller of the software-configured network, in accordance with the OpenFlow protocol, a command is added to add a new record to the network flow table of the OpenFlow switch or OpenFlow router.

Images