Simulation of Network Systems. ICS41: Computer Modeling and Simulation Lecture#3: 1

Transcription

1 Simulation of Network Systems ICS41: Computer Modeling and Simulation Lecture#3: 1

2 Network Simulation is a technique where a program simulates the behavior of a network. calculating the interaction between the different network entities (hosts/routers, data links, packets, etc) using mathematical formulas ICS41: Computer Modeling and Simulation Lecture#3: 2

3 Network Simulation When a simulation program is used in conjunction with live applications and services in order to observe end-to-end performance to the user desktop, this technique is also referred to as network emulation ICS41: Computer Modeling and Simulation Lecture#3: 3

4 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 to optimize technology decision-making. ICS41: Computer Modeling and Simulation Lecture#3: 4

5 Network Emulation Free software: ipfw or Dummynet runs on FreeBSD. netem is an optional part of recent Linux kernels. NISTnet is an emulator for Linux platforms. NS-2 is a popular network simulator that can also be used as a limited-functionality emulator. ICS41: Computer Modeling and Simulation Lecture#3: 5

6 Network Emulation Commercial software: Shunra VE Desktop runs on Microsoft Windows and simulates a network link, including latency, bandwidth, jitter and packet loss conditions. LANforge-ICE WAN Emulator runs on Linux and Microsoft Windows and supports bandwidthconstraints from 4 kbit/s to 1 Gbit/s, latency, jitter, packet loss/duplication/reordering and more. ICS41: Computer Modeling and Simulation Lecture#3: 6

7 Network Emulation Commercial devices: Anue Network Emulator, precision hardware based network emulators for Gigabit and ten Gigabit Ethernet, SONET/SDH and Fibre Channel. Shunra Virtual Enterprise, a comprehensive network simulation suite that simulates the network, remote locations, and the number and distribution of local and remote end-users for application and network testing. Apposite Technologies provides WAN emulation for terrestrial, wireless, and satellite links ICS41: Computer Modeling and Simulation Lecture#3: 7

8 Network Emulation Commercial devices: Packet Storm provides emulation at up to gigabit speeds Network Nightmare provides low end (< 20 Mbit/s) emulation Itheon Network Emulator provides Gigabit (10/100/1000) network environment emulation ICS41: Computer Modeling and Simulation Lecture#3: 8

9 Network Emulation Commercial devices: LANforge-ICE WAN Emulator supports bandwidth-constraints from 4 kbit/s to 1 Gbit/s, latency, jitter, packet loss/duplication/reordering Simena Network Emulator and Traffic Generator provides complete list of network impairments up to gigabit speeds, along with traffic injection and capture&replay. Maxwell, from InterWorking Labs, creates protocol impairments, not just packet impairments, on multiple, concurrent flows of network traffic ICS41: Computer Modeling and Simulation Lecture#3: 9

10 Network Simulation Uses: used to predict the behavior of networks and applications under different situations. researchers use network simulators to see how their protocols would behave if deployed. companies use simulators to design their networks and/or applications to get a feel for how they will perform under current or projected realworld conditions. ICS41: Computer Modeling and Simulation Lecture#3: 10

11 Network Simulation Uses: can also provide other tools to facilitate visual analysis of trends and potential trouble spots describe a computer simulation of a network of pipes or cables used in: pipeline transport (e.g. of natural gas, oil, water, etc.), electric power transmission, and electricity distribution. ICS41: Computer Modeling and Simulation Lecture#3: 11

12 Network Simulation Uses: to test: routing protocols, MAC protocols, transport protocols, applications, etc. ICS41: Computer Modeling and Simulation Lecture#3: 12

13 Simulator (network simulator) is the program in charge of calculating how the network would behave. may be distributed in source form (software) or provided in the form of a hardware appliance ICS41: Computer Modeling and Simulation Lecture#3: 13

14 Simulator (network simulator) Open source: NS-2, which runs on Linux, FreeBSD, SunOS, Solaris, Microsoft Windows and other operating systems. Proprietary Simulators: OPNET, Shunra, QualNet, and NetSim ICS41: Computer Modeling and Simulation Lecture#3: 14

15 Simulation input scripts or commands (network parameters) describe the state of the network (node placement, existing links) and the events (data transmissions, link failures, etc) trace files can document every event that occurred in the simulation and are used for analysis. ICS41: Computer Modeling and Simulation Lecture#3: 15