Post on 04-Jun-2018
8/13/2019 Mobile Networks Lab6
1/18
Performance Evaluation of Ethernet
Networks under different Scenarios
Lab 6
mobilenetworkslab@gmail.com
8/13/2019 Mobile Networks Lab6
2/18
Lab Objective
This lab is designed to demonstrate the operationof the Ethernet network.
The simulation in this lab will help you examinethe performance of the Ethernet network under
different scenarios.
In this lab you will set up an Ethernet a number ofnodes connected via a coaxial link in a bus
topology. The coaxial link is operating at a datarate of 10 Mbps.
You will study how the throughput of the networkis affected by the network load as well as the size
of the packets.
8/13/2019 Mobile Networks Lab6
3/18
Overview
The Ethernet is a working example of the more generalCarrier Sense, Multiple Access with Collision Detect(CSMA/CD) local area network technology. TheEthernet is a multiple-access network, meaning that aset of nodes sends and receives frames over a shared
link. The carrier sense in CSMA/CD means that all the
nodes can distinguish between an idle and a busy link.The collision detect means that a node listens as ittransmits and can therefore detect when a frame it is
transmitting has interfered (collided) with a frametransmitted by another node. The Ethernet is said to bea 1-persistent protocol because an adaptor with aframe to send, transmits with probability 1 whenever abusy line goes idle.
8/13/2019 Mobile Networks Lab6
4/18
Network Topology
Create Project with Office (200 x 100)m scale
Rapid Configuration (BUS)
Select Models (ethcoax)
8/13/2019 Mobile Networks Lab6
5/18
8/13/2019 Mobile Networks Lab6
6/18
Edit attributes of Coax Cable
Advance EditAttributes
Delay (0.05)
A higher delay is usedhere as an alternative to
generating higher traffic
which would require
much longer simulationtime.
Thickness (5)
8/13/2019 Mobile Networks Lab6
7/18
Configuring Network Nodes
Configure the traffic
generated by the nodes:
Select all nodes (Select
Similar Nodes) Edit Attributes (Apply
Changes to Selected
Objects)
Expand the Traffic
Generation Parameters
Expand Packet
Generation Arguments
8/13/2019 Mobile Networks Lab6
8/18
Promoted Attribute
To examine the network performance under
different loads, you need to run the simulation
several times by changing the load into the
network.
An easy way to do that is using promoted
attribute.The Interarrival Time attribute for
package generation can be assigned differentvalues during simulation time.
8/13/2019 Mobile Networks Lab6
9/18
Adding values for promoted attribute
Configure/Run
Simulation
Object Attributes
Click ADD
Select 1strow then
WILDCARD
On object attributes Click Values
Add the following 9
values
8/13/2019 Mobile Networks Lab6
10/18
Saving values in File
To save a scalar value that represents
the average load in the network
the average throughput of the network
Configure the simulator to save them in a file.
Click on the Advanced tab in the Configure
Simulation dialog box
Enter Scalar File Name
8/13/2019 Mobile Networks Lab6
11/18
Choose Statistics
Global Statistics
Traffic Sink (Traffic Received (pkt/sec))
Traffic Source (Traffic Sent (pkt/sec))
Collecting Scalar Value at the end of each
simulation run:
Choose Statistics (Advanced)
Global Statistics Probes Right-click on Traffic Received probeEdit Attributes. Set the
scalar data attribute to enabled Set the scalar type attribute
to time averageCompare to the following figure and click OK.
Repeat the previous step with the Traffic Sent probe.
Save the Probe Model (FileSave)
8/13/2019 Mobile Networks Lab6
12/18
Running Simulation
Run the simulation for 15 seconds
the simulator will be completing nine runs,
one for each traffic generation interarrival
time (representing the load into the network).
Notice that each successive run takes longer
to complete because the traffic intensity is
increasing.
8/13/2019 Mobile Networks Lab6
13/18
View Results
View Results (Advanced)
Select Load Output Scalar Filefrom the Filemenu
Select Create Scalar Panel from the Panelsmenu
Assign:
View and Analyze the resulting Graph
8/13/2019 Mobile Networks Lab6
14/18
Questions
Explain the graph wereceived in thesimulation that shows
the relationship betweenthe received throughput)and sent (load) packets.
Why does the
throughput drop whenthe load is either verylow or very high?
8/13/2019 Mobile Networks Lab6
15/18
Lab Task 2 Create three duplicates of the simulation scenario implemented in this lab. Name
these scenarios Coax_Q2a, Coax_Q2b, and Coax_Q2c. Set the Interarrival Timeattribute of the Packet Generation Arguments for all nodes (make sure to check
Apply Changes to Selected Objects while editing the attribute) in the new scenarios
as follows:
Coax_Q2a scenario: exponential(0.1)
Coax_Q2b scenario: exponential(0.05)
Coax_Q2c scenario: exponential(0.025)
In all the above new scenarios, open the Configure Simulation dialog box and from
the Object Attributes delete the multiple-value attribute (the only attribute shown in
the list).
Choose the following statistic for node 0: Ethcoax Collision Count. Make sure that
the following global statistic is chosen: Global StatisticsTraffic SinkTrafficReceived (packet/sec).
Run the simulation for all three new scenarios. Get two graphs: one to compare node
0s collision counts in these three scenarios and the other graph to compare the
received traffic from the three scenarios.
Explain the graphs and comment on the results. (Note: To compare results you needto select Compare Results from the Results menu after the simulation run is done.)
8/13/2019 Mobile Networks Lab6
16/18
Lab Task 3
To study the effect of the number of stations onEthernet segment performance, create a duplicate ofthe Coax_Q2c scenario, which you created in LabTask2.
Name the new scenario Coax_Q3. In the new scenario,remove the odd-numbered nodes, a total of 15 nodes(node 1, node 3, , and node 29).
Run the simulation for the new scenario. Create a
graph that compares node 0s collision counts inscenarios Coax_Q2c and Coax_Q3. Explain the graphand comment on the results.
8/13/2019 Mobile Networks Lab6
17/18
Lab Task 4
In the simulation a packet size of 1024 bytes is used(Note: Each Ethernet packet can contain up to 1500bytes of data). To study the effect of the packet size onthe throughput of the created Ethernet network,
create a duplicate of the Coax_Q2c scenario, which youcreated in Question 2. Name the new scenarioCoax_Q4. In the new scenario use a packet size of 512bytes (for all nodes). For both Coax_Q2c and Coax_Q4scenarios, choose the following global statistic:
Global StatisticsTrafficSinkTrafficReceived (bits/sec).Rerun the simulation of Coax_Q2c and Coax_Q4 scenarios.Create a graph that compares the throughput aspackets/sec and another graph that compares thethroughput as bits/sec in Coax_Q2c and Coax_Q4scenarios. Explain the graphs and comment on the results.
8/13/2019 Mobile Networks Lab6
18/18
Lab Report
Prepare a report that follows the guidelines
explained in Lab 3. The report should include
the answers to the above questions as well as
the graphs you generated from the simulationscenarios.
Discuss the results you obtained and compare
these results with your expectations. Mentionany anomalies or unexplained behaviors.