What is Network Analysis?

Network analysis is a general term for graph theory analysis, optimization analysis, and dynamic analysis of networks. Network analysis is to detect, analyze, and diagnose all transmitted data on the network, to help users eliminate network accidents, avoid security risks, improve network performance, and increase the value of network availability. Network analysis is a key part of network management and the most important technology. Network analysis generally includes the following analysis situations: quickly find and troubleshoot network failures; find network bottlenecks to improve network performance; find and resolve various network abnormal crises and improve security; manage resources, statistics and record the traffic and bandwidth of each node; specifications Network, view various applications, services, host connections, monitor network activities; analyze various network protocols, and manage network application quality.

Network analysis A method of calculating the network response when the stimulus and the network are known, also called circuit analysis. The most basic calculation rule is Kirchhoff's voltage law (KVL) and current law (KCL), plus the current-voltage relationship of each component in the network (abbreviated as VCR), and you can get enough network equations. (Usually a system of calculus equations) to find the required response. There are many different analysis methods depending on the type of excitation source and network, and the required solution response. The method of directly solving the network calculus equation belongs to time domain analysis or time domain solution, where the excitation and response are functions of time t; the method of using Laplace transform or Fourier transform to solve network equation belongs to frequency domain analysis or In the frequency domain, here the network equation is transformed into an algebraic equation, where the excitation and response are both functions of the complex frequency variable s or j.

Chinese name: Network analysis
Foreign name: network analysis

Content: Graph theory analysis, optimization, and dynamic analysis
Applied discipline: Network security, management, telecommunications
Function: Eliminate network accidents and avoid security risks

Network analysis steady state analysis

A sinusoidal excitation is a common and important situation. The method of solving its steady-state response is the phasor method (also known as the symbol method). The excitation and response at this time are sinusoidal functions of the same frequency, and both can be represented by a phasor that includes only its amplitude and primary phase. E.g:

Voltage phasor

Means,

Current phasor

Means. Using the phasor method, the calculus equation can be transformed into an algebraic equation, and the current-voltage relationship of the network element can be expressed by impedance or admittance. There are various analysis methods depending on the response required, and they all derive their corresponding network equations on the basis of KVL, KCL and VCR. For simple networks, the network equations can be listed by observation, and the network theorem and equivalent transformation can be used to simplify the solution process. For complex networks, network graph theory and matrices are often used to systematically list their network equations and solve them with a computer. The following six methods are commonly used.

2.1 Node voltage method

The voltage between a certain reference node is calculated by each node in the network. This network equation is called a node equation, and its matrix formula is:

Where U _n is the vector of the voltage of each node to be obtained; I _g is the current excitation source vector at each node is the node admittance matrix.

2.2 Loop current method

Taking the imaginary current flowing in each independent loop as the quantity to be sought, the network equation at this time is called the loop equation, and its matrix formula is:

Where I _m is the vector of the loop current to be obtained; U _g is the voltage excitation source vector of each loop; Z _m is the loop impedance matrix.

2.3 Port Analysis

Sometimes it is not required to find the current and voltage everywhere in the network, but only to care about the current and voltage on those terminals connected to the network. In this case, the network can be treated as a multi-terminal network. The most common is a dual-port network The system of equations related to the current and voltage on these ports is generally small and relatively easy to solve (only two equations are required for a dual-port network).

2.4 Network Function Method

When the network has only one excitation source (set its phasor x) and only one response (set its phasor to derive the network equation linking these two quantities as:

In the formula, H (j) is a network function, which is generally a function of frequency , and its dimension can be impedance, admittance, or dimensionless current ratio and voltage ratio, depending on the dimension of work and 7. Once H (j) is known, the response y can be obtained from a given x, and it is convenient to check its frequency characteristics.

2.5 Indefinite Admittance Matrix Method

Taking the voltage of a network external terminal to a reference point outside the network as the quantity to be calculated, the matrix equation of the network equation is:

Where U is the vector of the voltage of each external terminal to the reference point; I is the vector of the current of each terminal; Y _ind is the coefficient matrix of the equation and is called the indefinite admittance matrix (which is a singular matrix). Because it has simple and systematic writing and solving methods, and is suitable for computer processing, it is an important method for analyzing linear passive and active networks.

2.6 Topological Analysis

One type of topology method is to express the relationship between physical quantities such as current and voltage in the electrical network with a line graph, and then to obtain the network function according to the simplified rules or formulas of the line graph. The typical method is the signal flow graph method. The other is to obtain the network function by calculating the branch admittance products of various trees according to the line diagram of the electrical network and the component parameters in the network. This method is called tree enumeration or K-tree. Topological analysis methods are suitable for processing by computers, and it is easy to derive network functions with symbols, but they can handle smaller electrical networks.

The DC excitation can be treated as a special case of sinusoidal excitation equal to zero. For periodic signals, it can be decomposed into many sinusoidal components with different frequencies by means of Fourier series. Since the linear network obeys the superposition theorem, it can be calculated separately using the phasor method. The response of each sine component can be added and then superimposed.

Linear network analysis under non-periodic signal excitation can be solved with the help of Laplace transform, which transforms the network's calculus equation into an algebraic equation, and the current-voltage relationship of the network element is expressed by operational impedance and operational admittance. Transformations V (s) and I (s) that convert the sum in the network into complex numbers. This method can be regarded as a generalization of the phasor method. It replaces j in the phasor method with a complex frequency s (here s = + j), so it is called an algorithm. It can be used in various solutions in the phasor method. If a time-domain function formula of the response is also required, the inverse Laplace transform of the response transformation formula should be obtained.

3.1 State variable analysis

It is suitable for both linear time-invariant networks and time-varying and nonlinear networks. For a linear time-invariant network, capacitance, voltage, inductance, and current are usually used as state variables, and a set of first-order differential equations that use them as quantities to be calculated-state equations. The equation of state can be derived from the network's topological graph, or it can be derived from the network's higher-order differential equations or network functions. The advantage of this method is that there are abundant methods for solving such first-order differential equations, and it is suitable for computer processing. It is also easy to apply to time-varying and non-linear networks.

In addition to the state variable method, linear time-varying network analysis can also use time-varying network functions. For non-linear networks, the network equations derived from KVL, KCL and VCR are non-linear equations. Generally there are no closed solutions, and they are usually solved by numerical or graphical methods.

3.2 Computer-Aided Analysis of the Network

With the development of computer technology, a general network analysis program appeared in the 1960s, which not only facilitated calculation, but also promoted the development of network theory. This kind of universal network analysis program can be used for DC analysis, sinusoidal steady state analysis, transient analysis, noise analysis, tolerance analysis, and nonlinear network analysis. Many methods are used in the program, such as improved node method, state variable method, and mixed analysis method, and techniques such as sparse matrix are introduced to improve the efficiency of solving equations.

Network Analysis Network Management

Improve the overall level of domestic network management

Compared with overseas, domestic network management started late, and the management level of users is not as good as overseas. Claire actively applies this technology to network fault resolution, network performance improvement and network security protection. It aims to improve the level of domestic network management, shorten the gap with foreign countries, and help users realize full visualization of their networks. The phenomenon sees the essence and truly controls its own network.

Help network managers refine network management

Network analysis technology is the key to network management, and it is a necessary technology for the network to enter deep management. The popularity of network analysis technology is also an inevitable trend. Kelai actively helps users build in-depth knowledge of this technology! The free version of the software is launched on the official website for the exchange of technical enthusiasts. At the same time, it provides a large number of technical learning documents and video materials. The popularity in the country allows users to effectively access advanced network management technology.

Promote network analysis technology exchange

Kelai Software actively organizes various technical exchange activities. In addition to regular product and technical training, exchange activities with industries such as finance, telecommunications, energy, and government have promoted the application of network analysis technology in the industry more widely and in depth. At the same time, technology applications More practical needs.

Key to network analysis management

Network management faces huge challenges

Today's network management requires network analysis technology more than ever! The network is constantly generating new critical applications. The expansion of the scale and the complication of the structure have caused users to continuously increase the management and maintenance costs of the network. At the same time, viruses, attacks and network failures are threatening the health of the network at all times development of. Effectively guarantee the continuous, efficient and secure development of the network, making network analysis technology the key to network management!

Network analysis breakthrough direction

Expanding Network Horizons

Through comprehensive monitoring and analysis of network data, network problems caused by various network application behaviors are obtained from the underlying data of the network, and they can be quickly located to better prevent security policies and manage faults and performance more reasonably.

Fine network management

Network maintenance is becoming more and more complicated. It is an inevitable trend for network management to be refined. Network analysis technology is a powerful guarantee for refined management by capturing data packets at the bottom of the network and decoding, analyzing, and diagnosing them.

Perspective network behavior

Only through the use of network analysis technology can its network behavior, information interaction, and data transmission process be fully visible, and it can provide reliable data support for troubleshooting, performance improvement, and network security issues.

Network analysis analysis value

Network analysis upgrade network back analysis

The value of back analysis

Discover network-wide communication records and monitoring, proactively discover network value space and potential network risks.

Track and establish association indexes of network communication data, high-precision and deep mining of massive data, and long-term trend statistics.

Reorganization, restoration and reproduction of forensic network events for security event forensics and prevention of network problems.

Network analysis network analysis

The network analysis system is a network management solution that allows network managers to take appropriate measures in various network problems. It detects, analyzes, and diagnoses all transmitted data on the network, helping users eliminate network accidents, avoid security risks, and improve Network performance increases the value of network availability.

Managers no longer need to worry about network accidents being difficult to resolve. Kelai's network analysis system can help enterprises minimize network failures and security risks, and network performance will gradually improve. It brings network managers:

Quickly find and troubleshoot network problems;
Find network bottlenecks to improve network performance;
Discover and resolve various network anomalies and improve security;
Manage resources, statistics and record the traffic and bandwidth of each node;
Standardize the network, view the connections of various applications, services, hosts, and monitor network activities;
Manage web applications.

Network analysis

The continuous, efficient and secure operation of the network is the basis for the normal operation of the user's business. This requires network managers to be able to grasp key indicators of business application operation at any time, detect abnormalities in time and provide early warning, and implement active operation and maintenance and management. When faults occur, they can quickly and effectively locate problem points, clarify responsibilities, and analyze the cause. Reduce downtime; once the network receives an attack or a security event, it needs to have the means and basis to effectively locate, analyze, and obtain evidence. "Kelea Network Backtracking Analysis System" is an intelligent, distributed network analysis platform that meets the increasing needs of users for network failure, performance, and security analysis.

The value of back analysis:

"Kelea Network Backtracking Analysis System" is a high-performance hardware platform integrating network seven-layer protocol analysis technology, high-performance data storage and intelligent data mining technology, and distributed data processing technology. It can provide users with other network management and security products. Irreplaceable value.

Discovery-real-time network communication analysis and monitoring to proactively discover abnormal behaviors and hidden dangers of security faults in the network.

Tracking-intelligent data mining and communication analysis to quickly locate the root cause of the failure and restore the network attack process.

ForensicsRestore and reproduce the original communication data of the network. It is used for packet-level auditing and forensics of security events.