some functionality can only be provided by the network- more expensive network.To validate that the simulation works accurately, the output trace file of NS2 after simulation is compared with the traffic generated at the destinations of the production network.1EE 122: Network ApplicationsKevin LaiAug 28, 2Network FunctionalityNetwork functionality is only useful if it benefits users- also applies to any computer system, but easier to forget in networking- e.g., Is it worth it to upgrade a 56Kb/s modem link in your network to 100Mb/s Ethernet? Only if it significantly improves user experienceGeneralization of Amdahl’s Law from computer architecture- Also applies to metrics other than timeenhancedenhancedenhancednewoldoverallspeedupfractionfractiontimeexecutiontimeexecutionSpeedup+−=)1( 3Network Applicationshow networks affect users- buy stock in networking companies, work for networking companies- use network applicationsneed to understand application requirements- to build useful networks- to understand why networks are built the way they are- to understand why some ideas 4Different Network Applicationstelephony (making a phone call)sending emailweb browsing- buying something- reading newssending instant messagesfile sharingplaying a distributed game watching/listening to streaming 5Requirements of the Network throughputlatency cost- compatibility with existing equipment usually lowers cost qualifications- distribution: mean, worst-case- in small bursts / all the timeease of programmabilityrouting- unicast, multicast, 6Web Browsing Network RequirementsTransfer 1KB-100KB files- e.g., HTML file, JPEG image Depends on size of content at sites visitedNews oriented sizes (e.g., Average throughput 32Kb/s – 1Mb/s- Average latency 100 – 250ms- Average loss < 10%Flat rate $20-$50/ 7Telephony Network Requirements Stream data at 9.6Kb/s – 128Kb/s- an encoded audio signalWired- Worst case throughput 64Kb/s – 128Kb/s- Worst case latency 100ms – 125ms- Loss < 1%- $.01-$.10/minuteMobile- Worst case throughput 9.6Kb/s – 128Kb/s- Worst case latency 100ms – 250ms- Loss < 10%- $.10-$1/ 8File Sharing RequirementsTransfer 3MB – 600MB file- MP3 audio file, MPEG video fileInbound throughput 128Kb/s – 10Mb/sOutbound throughput 128Kb/s – ? Mb/sFlat rate $20-$50/ 9Distributed Game Requirementse.g., WarCraft III, Quake III, EverQuest- unlimited number of players stream data about player’s state- e.g., location in the world, appearance, items carried, units controlled, etc.Throughput 128Kb/s – ? Mb/sLatency 0ms – 250msFlat rate $20-$50/ 10Comparing ApplicationsResearch community consistently failed to predict next popular application- predicted: telnet actually: email- predicted: ftp actually: Deliver a packet with unknown delay for $.10/Mb, but less delay than people paying $.05/Mb- Deliver a packet with unknown delay, maybeWhich model satisfies which application?What model do existing networks 13Service Model PhilosophiesProvide functionality for existing popular application- e.g., telephone network- less work for application developers This traffic test file is then used by the NS2 traffic agents in the simulated network model representing the real production network. Analyzed the performance of 5 node network when the packet is drop down by graphical method also called as Xgraph when rate parameter is in mb and also analyzed the performance of same network by changing the value of rate parameter at same time so no packets would drop down at same time and also analyzed the performance by Xgraph method.In this work, a modified sniffer program was used to capture real traffic data from a production network and output to a traffic text file. We also simulate the design of 5 node wired network scenario, its packet drop rate analysis through TCP protocol using NS2 as a simulator. The aim of this paper is to demonstrate how traffic agents in NS2 simulator are used to generate different types of traffic based on real traffic network. Normally the traffic in NS2 is generated from the traffic agents such as TCP and UDP agents whose parameters are based on certain statistical distribution. Wired networks can also be used as part of other wired and wireless networks. Ethernet is the fastest wired network protocol, with connection speeds of 10 megabits per second (Mbps) to 100 Mbps or higher. One of the challenges in NS2 modeling is to seamlessly integrate real world traffic data into the NS2 network model. There has been substantial interest from researchers in the development and contribution of modules in NS2.
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