Network emulation
Encyclopedia
Network emulation is a technique where the properties of an existing, planned and/or non-ideal network
are simulated in order to assess performance, predict the impact of change, or otherwise optimize technology decision-making.
can be accomplished by introducing a device on the LAN
that alters packet flow in a way that imitates the behavior of application traffic in the environment being emulated. This device may be either a general-purpose computer running software
to perform the network emulation or a dedicated emulation device
. The device incorporates a variety of network attributes into its emulation model – including the round-trip time across the network (latency
), the amount of available bandwidth
, a given degree of packet loss
, duplication of packets, reordering packets, and/or the severity of network jitter
. Desktop PCs can be connected to the emulated environment, so that users can experience the performance and behavior of applications in that environment first-hand. Similarly, phones can be connected to the emulated environment so that users can directly assess VoIP
call quality for themselves.
in that a network emulator appears to be a network; end-systems such as computer
s can be attached to the emulator and will behave as if they are attached to a network. Network simulators are typically programs which run on a single computer, take an abstract description of the network traffic (such as a flow arrival process) and yield performance statistics (such as buffer occupancy as a function of time).
A network emulator emulates the network which connects end-systems, not the end-systems themselves. Systems which emulate the end-systems are called traffic generators.
Telecommunications network
A telecommunications network is a collection of terminals, links and nodes which connect together to enable telecommunication between users of the terminals. Networks may use circuit switching or message switching. Each terminal in the network must have a unique address so messages or connections...
are simulated in order to assess performance, predict the impact of change, or otherwise optimize technology decision-making.
Methods of emulation
Network emulationEmulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
can be accomplished by introducing a device on the LAN
Län
Län and lääni refer to the administrative divisions used in Sweden and previously in Finland. The provinces of Finland were abolished on January 1, 2010....
that alters packet flow in a way that imitates the behavior of application traffic in the environment being emulated. This device may be either a general-purpose computer running software
Computer software
Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it....
to perform the network emulation or a dedicated emulation device
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
. The device incorporates a variety of network attributes into its emulation model – including the round-trip time across the network (latency
Lag
Lag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
), the amount of available bandwidth
Bandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
, a given degree of packet loss
Packet loss
Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is distinguished as one of the three main error types encountered in digital communications; the other two being bit error and spurious packets caused due to noise.-...
, duplication of packets, reordering packets, and/or the severity of network jitter
Jitter
Jitter is the undesired deviation from true periodicity of an assumed periodic signal in electronics and telecommunications, often in relation to a reference clock source. Jitter may be observed in characteristics such as the frequency of successive pulses, the signal amplitude, or phase of...
. Desktop PCs can be connected to the emulated environment, so that users can experience the performance and behavior of applications in that environment first-hand. Similarly, phones can be connected to the emulated environment so that users can directly assess VoIP
Voice over IP
Voice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...
call quality for themselves.
Emulation, simulation and traffic generation
Emulation differs from simulationSimulation
Simulation is the imitation of some real thing available, state of affairs, or process. The act of simulating something generally entails representing certain key characteristics or behaviours of a selected physical or abstract system....
in that a network emulator appears to be a network; end-systems such as computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
s can be attached to the emulator and will behave as if they are attached to a network. Network simulators are typically programs which run on a single computer, take an abstract description of the network traffic (such as a flow arrival process) and yield performance statistics (such as buffer occupancy as a function of time).
A network emulator emulates the network which connects end-systems, not the end-systems themselves. Systems which emulate the end-systems are called traffic generators.
Network simulation software
- NS-2Ns (simulator)ns is a name for series of discrete event network simulators, specifically ns-1, ns-2 and ns-3...
is a popular free network simulator that can also be used as a limited-functionality emulator. - NIST Net is a network emulation package that runs on Linux. NIST Net allows a single Linux PC set up as a router to emulate a wide variety of network conditions.
See also
- NetflowNetflowNetFlow is a network protocol developed by Cisco Systems for collecting IP traffic information. NetFlow has become an industry standard for traffic monitoring and is supported by platforms other than Cisco IOS and NXOS such as Juniper routers, Enterasys Switches, vNetworking in version 5 of...
- Network simulatorNetwork simulatorA network simulator is a piece of software or hardware that predicts the behavior of a network, without an actual network being present.-Uses of network simulators:Network simulators serve a variety of needs...
- Network simulationNetwork simulationIn communication and computer network research, network simulation is a technique where a program models the behavior of a network either by calculating the interaction between the different network entities using mathematical formulas, or actually capturing and playing back observations from a...
- Network traffic simulationNetwork traffic simulationNetwork traffic simulation is a process used in telecommunications engineering to measure the efficiency of a communications network.-Overview:...
- Traffic generation model
- Packet flow