21-09-2016, 09:58 AM
Design Routing Protocol Performance Comparison in NS2:
AODV comparing to DSR as Example
1455513547-adovcns2.pdf (Size: 409.28 KB / Downloads: 13)
Abstract
There are already many projects try to tell us how to
use NS-2 easily, while not as that difficult as its official
manual says. However, how to easily use NS-2 to do
performance evaluation is still lacking. Usually, a trace
file which comes out from one time NS-2 simulation is
larger than 600MB, to analysis this huge file definitely
will cost great time. Till now, there are many evaluation
methods, but use them is very time cost and may not
exactly what the simple version we want. This paper is to
let people who use NS-2 can easily do the work of network
post simulation. Thus make it easier and faster in making
NS-2 more practical. Furthermore, this paper apply this
performance evaluation method on the comparison of two
on-demand source routing protocols AODV and DSR, and
shows DSR is somewhat suitable for sensor work
applications
1. Introduction
Ns-2 is an object-oriented simulator developed as part
of the VINT project at the University of California in
Berkeley. The project is funded by DARPA in
collaboration with XEROX Palo Alto Research Center
(PARC) and Lawrence Berkeley National Laboratory
(LBNL). Ns-2 is extensively used by the networking
research community. It provides substantial support for
simulation of TCP, routing, multicast protocols over
wired and wireless (local and satellite) networks, etc.
The simulator is event-driven and runs in a
non-realtime fashion. It consists of C++ core methods
and uses Tcl and Object Tcl shell as interface allowing
the input file (simulation script) to describe the model
to simulate. Users can define arbitrary network
topologies composed of nodes, routers, links and
shared media. A rich set of protocol objects can then be
attached to nodes, usually as agents. It had already
become the ”de facto” standard in networking research
Although NS is fairly to use once you get to know
the simulator, it is quite difficult for a first time user,
because there are few user-friendly manuals. Even
though there is lots documentation written by the
developers who has in depth explanation of simulator,
it is written with the depth of a skilled NS user.
There already are many user friendly tutorials to
make how to use ns-2 easily [3, 4]. They give a new
user some basic idea of how the simulator works, how
to setup simulation networks, where to look for further
information about network components in simulator
codes, how to create new network components, and so
on. They are mainly focus on simple examples and
brief explanations. Although all the usage of the
simulator or possible network simulation setups may
not be covered in those projects, the projects also help a
new user to get quick started. However, with this good
tutorials material available today, there still lack
documents to ease the analysis work of post-simulation.
Since ns-2 is an academic project, the main purpose is
for evaluating the existing network’s performance or
the performance of network with new design of
component [6, 7]. Thus, to make progress on this
problem, this paper is to let people who use ns-2 can
easily do the work of network post simulation analysis,
which will further make ns-2 more practical on doing
scalable simulation.
In the rest of this paper, section 2 will discuss how to
conduct a wireless simulation in ns-2; section 3 will
describe about the trace file format of ns-2, and then
section 4 will do analysis on two sample routing
protocols, AODV and DSR, and also show how our
performance evaluation mode can work on the analysis
of them.
2. Wireless simulation in NS-2
2.1. Software structure and mechanism of NS-2
The key to get to know ns-2 is it is a discrete event
network simulator. In ns-2 network physical activities
are translated to events, events are queued and
processed in the order of their scheduled occurrences.
And the simulation time progresses with the events
processed. And also the simulation “time” may not be
the real life time as we “inputted”.
But, why is ns-2 that useful, what kind of work can
be done by ns-2, it can model essential network
components, traffic models and applications. Typically,
it can configure transport layer protocols, routing
protocols, interface queues, and also link layer
mechanisms. We can easily see that this software tool
in fact could provide us a whole view of the network
construction, meanwhile, it also maintain the flexibility
for us to decide. Thus, just this one software can help
us simulate nearly all parts of the network [1-5]. This
definitely will save us great amount of cost invested on
net work constructing. The following Figure 1 shows a
layered structure which ns-2 can simulate for us
After the simulation finish, the way ns-2 used to
present the most details information on that much
network layer is that it provides us a huge trace file
recording all the events line by line in it. So, now we
see why event driven mechanism is used in ns-2, since
it really could maintain the things ever happened as
records. And we can trace these records to evaluate the
performance of special stuffs in our network, such as routing protocol, Mac layer load, and so on.