25-04-2011, 11:37 AM
SUBMITTED BY:
NC ANUM AHMED PIRKANI
NC SADIA RIFFAT
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NETWORK SIMULATOR 2 (NS2):
This assignment has been done with the help of network simulator 2. Using this simulator, we have analyzed in detail TCP and UDP flows.
NS2 was installed using the ubuntu software.
Using this software, we made both the trace files and the NAM file for the different specifications of transport layer protocols i.e. TCP and UDP and corresponding application layer protocols given for them.
When the simulation is run, the trace file gives a lot of information about the simulation results i.e., using it; we can plot the graph which gives the relationship between different parameters.
With the help of NAM file, we can practically see the flow of packets between different nodes. Along with it, we can also see the packet loss.
INTRODUCTION:
Using this simulator, we tried to make different protocols and analyzed the changes occurring in them by changing the transport layer protocol and the application layer protocol.
MORE ABOUT NS:
NS (network simulator) is basically used to design network protocols which may be wired and wireless.
NS provides substantial support for simulation of TCP, routing and multicast protocols.
Different network protocols can be compared with one another.
Nam can be used to see the packet movement, queue build-up and packet loss directly. It is used to visualize the animation of the flow.
It has two type of files:
• NAM file:
We can see animations of the network protocol designed using this NAM file.
A snapshot of a NAM file is as under:
NAM interface
Color
Node manipulation
Link manipulation
Topology layout
Protocol state
• TRACE FILE:
This file contains the code established for the network protocol. With the help of this file, we can get all the information about the specifications of network which may include
Nodes involved( sources and destinations)
Position of several nodes
Bandwidths
No of bytes during flow
Window size
Time for flow
Throughput
Type of transport and application layer protocol
Basically, with the trace file, we can come to know all what is happening in our network protocol.
With the help of this trace file, we can plot a graph which can be used to see the relationship between different parameters like the type of transport protocol e.t.c.
STEPS:
Some of the steps which can be used while designing the protocol are:
Create simulator
Create an event scheduler
Turn the tracing on
Create network topology
setup packet loss, page link dynamics e.t.c
setup routing agents
Create connections(transport) between nodes
Create traffic
Start simulation
XGRAPH:
It draws a graph on an X display given data read from data files or from some input.
DESCRIPTION OF QUESTION:
Following specifications define the assignment.
The delays have been mentioned on the figure.
FLOW1: N1-N5
FLOW2: N2-N6
For the TCP transport layer protocol, we have FTP application layer protocol while, for the UDP transport layer protocol, we have CBR application layer protocol.
For the given questions, we have different TCP flavors i.e. TCP reno and TCP tahoe.
Queue size is specified to be 10 for all questions.
For all the questions, we have to calculate the average throughput i.e. the throughput during whole time interval.
ANALYSIS
QUESTION NO. 1:
Read about TCP Reno, TCP Tahoe and TCP SACK. Provide a comparison of the three TCP flavors, preferably in a table format. Finally provide a short analysis/result on which of the three is better. Your analysis must be precise not exceeding 15-20 lines.
ANSWER:
TCP:
It is a reliable connection oriented protocol. It ensures reliability of packet transference due to acknowledgements. Reliability is ensured by starting a timer whenever a packet is sent. If the acknowledgement is received within the time then its fine else wise, there is packet loss.