Figure 4.1 A snapshot of CRAFT network in NAM
NSSL Home > Scientific Publications > Technical Memorandum NSSL-107
In order to understand how well the CRAFT network performs and to predict its performance as a possible nationwide operational radar data delivery system in the future, it is crucial to examine the network in detail. In particular, network properties such as bandwidth, local buffer, and latency play a very important role in understanding the network performance. These parameters are studied through a simulation of the initial test bed of 6 radars in Oklahoma.
The simulation is done using the Network Simulator (NS). NS (version 2) is an object-oriented, discrete event driven network simulator developed at UC Berkeley written in C++ and OTcl. NS is primarily useful for simulating local and wide area networks. It implements network protocols such as TCP and UDP, traffic source behavior such as FTP, Telnet, Web, CBR and VBR, router queue management mechanism such as Drop Tail, RED and CBQ, and routing algorithms such as Dijkstra, and more. Due to its implementation of a wide variety of network functionalities, NS was determined to be a suitable candidate for simulating the CRAFT network.
There are two languages, namely C++ and OTcl, that comprise the NS simulation software package. C++, which can efficiently manipulate bytes, packet headers, and implement algorithms that run over large data sets, is suitable for detailed protocol implementation. On the other hand, OTcl enables fast exploration of a number of scenarios due to its nature of simple syntax. The CRAFT network simulation was written in OTcl only, making use of the default NS built-in classes (Appendix A).
The NS outputs several text files containing statistics information (Appendix B) and information for the input to a graphical display tool called Network Animator (NAM). The following figure shows a snapshot of the graphical representation of the CRAFT network in NAM:
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Figure 4.1 A snapshot of CRAFT network in NAM |