Network simulation

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In computer network research, network simulation is a technique whereby a software program replicates the behavior of a real network. This is achieved by calculating the interactions between the different network entities such as routers, switches, nodes, access points, links, etc.^[1] Most simulators use discrete event simulation in which the modeling of systems in which state variables change at discrete points in time. The behavior of the network and the various applications and services it supports can then be observed in a test lab; various attributes of the environment can also be modified in a controlled manner to assess how the network/protocols would behave under different conditions.

Network simulator

A network simulator is a

Network emulation allows users to introduce real devices and applications into a test network (simulated) that alters packet flow in such a way as to mimic the behavior of a live network. Live traffic can pass through the simulator and be affected by objects within the simulation.

The typical methodology is that real packets from a live application are sent to the emulation server (where the virtual network is simulated). The real packet gets 'modulated' into a simulation packet. The simulation packet gets demodulated into a real packet after experiencing effects of loss, errors, delay, jitter etc., thereby transferring these network effects into the real packet. Thus it is as-if the real packet flowed through a real network but in reality it flowed through the simulated network.

Emulation is widely used in the design stage for validating communication networks prior to deployment.

List of network simulators

There are both free/open-source and proprietary network simulators available. Examples of notable open source network simulators / emulators include:

• ns Simulator
• GloMoSim

There are also some notable closed source network simulators. These include:

• OPNET (Riverbed)
• NetSim (Tetcos)

Uses of network simulators

Network simulators provide a cost-effective method for

• 5G-NR capacity, throughput and latency analysis
• Network R & D (More than 70% of all Network
  Research paper
  reference a network simulator)
• Defense applications such as
  MANET Radios, Tactical data links
  etc.
• VANET
  simulations
• UAV network/drone swarm communication simulation
• Machine Learning
  : Testing ML algorithms for optimizing network parameters, generating synthetic data training ML algorithms on networks
• Education: Online courses, Lab experimentation, and R & D. Most universities use a network simulator for teaching / R & D since it is too expensive to buy hardware equipment

There are a wide variety of network simulators, ranging from the very simple to the very complex. Minimally, a network simulator must enable a user to

• Model the network topology specifying the nodes on the network and the links between those nodes
• Model the application flow (traffic) between the nodes
• Providing network performance metrics as output
• Visualization of the packet flow
• Technology/protocol evaluation and device designs
• Logging of packet/events for drill-down analyses/debugging

See also

• Network emulation
• Traffic generation model

References