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CHAPTER – 4

4. Simulation procedure

4.1 Introduction

The main aim of this chapter is to discuss the simulation procedure followed in

evaluating the performance of AODV under black hole attacks. As discussed in the

previous chapters OPNET modeler is used as the simulation tool and three

scenarios are created. First scenario has normal mobile ad hoc network with

AODV as routing protocol and works under ideal working conditions. Second

scenario has Balckhole attacks and the third scenario is used to analyze and

improve the performance of AODV. The actual simulation setup used and the

procedure followed to create the required scenarios is given in this chapter as

below.

4.2 Mobile Ad hoc network setup for normal scenario

As discussed Mobile ad hoc network is used for evaluating the performance of

AODV routing protocol under black hole attacks and thus in this context a simple

MANET is simulated using OPNET. Following steps are followed to create the

basic MANET

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• A new project is chosen from the file menu and a blank scenario is used to

create the first scenario

• Campus is chosen as the required network scale and the size is set to

1000X1000 meters and thus now the MANET operates within a campus

• MANET is chosen as the model family from the list of models available

with OPNET modeler

• Now a blank workspace is created and the required objects can be used for

the simulation from the object palette and a typical object palette provided

with OPNET modeler is as given below

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From the above screen it can be observed that there are number of objects for

MANET simulation and few of them are used across this scenario and they are as

listed below

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• Wireless LAN mobile workstations are used as the mobile clients and in this

scenario a total of 26 mobile nodes are used[43]. They are dragged from the

object palette towards the workspace

• Application configuration is used to set the applications used across the

network and in this scenario FTP and Web applications are used.

• Profile configuration object is used to set the required profiles for the

applications and detailed configuration details are discussed in the later

sections

• Mobile configuration object is used to set the mobility profiles for all the

mobile nodes and a detailed configuration is discussed in the later

sections[2,12,44].

Above listed objects are used for the simulation of the MANET and the detailed

configuration settings done are as explained below

4.2.1 Application Configuration definitions

Application configuration object is used to define the required applications that

generate the traffic over the network. Application configuration object has an

option to create any number of applications and in this simulation two applications

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are used like FTP (File Transfer Protocol) and Web. Required configurations are

used to set the applications and the corresponding screenshot is as given below

From the above graph it can be understood that there are two applications used like

FTP where medium load is imposed over the network and for the Web application

a simple HTTP is used with heavy browsing[45]. Once the required applications

are create now the corresponding profiles should be created to support the

application traffic and the corresponding procedure followed in this context is as

given below

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4.2.2 Profile configuration settings

There are two applications across the network and to generate the required

application traffic corresponding profiles need to be created. Profile configuration

object is used to create the profile and as there are two application two profiles are

created and the corresponding screenshot is as given below

From the above screen it is clear that there are two profiles like FTP and Web and

the corresponding settings are done. Start time offset for both the profiles is set to a

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constant value of 100 seconds and duration is set to end of simulation. Once the

profiles are created now all the mobile nodes and the wireless LAN server should

support the corresponding application traffic and the configuration are explained in

the later sections.[46]

4.2.3 Mobility configuration

Mobility configuration is required to set the mobility patterns for all the 26 mobile

nodes used across the simulation. There are number of mobility models available

for simulation and in this scenario default random way point mobility is used and

the corresponding screen is as given below

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From the above screen it is clear that default random way point is used as the

required mobility model for the mobile nodes. Speed of the mobile nodes is set o a

constant value of 50 seconds, pause time I set to 0 seconds, start time is set to a

constant value of 15 seconds and the stop time is till end of the simulation. Once

the mobility model is set for the mobile nodes across the network now the nodes

should support the mobility and the corresponding procedure is as explained below

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4.2.4 Mobile nodes and wireless LAN server configurations

As discussed in the previous sections there are 26 mobile nodes and a single

wireless LAN server and these mobile nodes acts as application clients and WLAN

server acts as application server. For communication among these clients and

server always a protocol is required and in this simulation AODV is used as the

required routing protocol. The actual procedure followed in this context is given in

the below screen[47].

From the above screen it is clear that AODV is used as the ad hoc routing protocol.

All the mobile nodes and the wireless LAN server are selected and similar settings

are done. Now all the nodes and server communicates using the AODV protocol

and as the main aim of this simulation is to evaluate the performance of AODV

under Balckhole attacks the corresponding AODV attributes are modified due to

the attacks in the next scenario. In this scenario default AODV routing protocol

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parameters are used. Once the AODV routing protocol is set for the simulation

now the next process is to assign the application traffic to the mobile nodes and the

procedure followed in this context is given below

• Deploy defined applications option is chosen from the protocols application

menu

• All the mobile nodes are deployed towards the FTP and Web clients and the

wireless LAN server is assigned to both the FTP and HTTP server and the

corresponding screenshot is as given below[48].

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From the above screen it is clear that all the mobile nodes are assigned to source of

both the FTP and Web profiles and the WLAN server is assigned to FTP and Web

server. Now the mobile nodes act as the FTP and Web clients and the WLAN

server acts as both the FTP and Web server. Now all the mobile nodes should

support the mobility model created across the mobile configuration object and the

corresponding procedure is shown in the below screenshot[49].

Set mobility profile is used to set the mobility defined across the mobile

configuration and as the mobility used is default mobility all the mobile nodes now

follow the corresponding mobility patterns. Once the basic network setup is ready

the corresponding network is as shown below

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4.2.5 Performance metrics

As the main aim of this simulation is to evaluate the performance of AODV under

Black hole attacks evaluation of performance is required. OPNET provides options

to evaluate the performance across global level, node level and link level and in

this simulation global level metrics are chosen and the corresponding screenshot is

as given below

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From the above screen it can be observed that four levels of performance metrics

are chosen for this simulation like AODV, FTP, HTTP and wireless LAN and the

actual values used in here are as given below[50].

Following are the performance metrics used for AODV routing protocol

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• Number of hopes per route

• Route discovery time

• Routing traffic received and sent in bits per sec and packets per sec

• Total acknowledgments and cache replies sent

• Total packets dropped

• Total replies sent from destination

• Total route errors sent

• Total route replies sent

• Total requests sent

Following are the performance metrics used for FTP application

• Download response time

• Total traffic sent and received in bytes per sec and packets per sec

• Upload response time

Following are the performance metrics used for HTTP application

• Object response time

• Page response time

• Traffic sent and received in bytes per sec and packets per sec

Following are the performance metrics used for Wireless LAN server

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• Data dropped

• Delay

• Load

• Medium access delay

• Network load

• Retransmission attempts

• Throughput

Once the required simulation metrics are chosen first scenario is ready to simulate

and the procedure followed to create the second scenario is as given below

4.3 Blackhole attacks scenario

First scenario is duplicated to create the second scenario and the main aim of this

scenario is to impose Blackhole attacks across the network[51]. As it is not

possible to impose physical attacks over the network required configuration

changes are done for creating the simulated Blackhole attacks. In general when

there are some Blackhole attacks over the network behavior of the AODV routing

protocol is altered against the configuration details. Following are few changes

made to the parameters of AODV routing protocol and the corresponding

screenshot is as given below

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From the above screen it is clear that route discovery parameters, active route

timeout, hello interval loss, allowed hello loss and other parameters are altered

when compared to first scenario. Few changes are also made to wireless LAN

server parameters and they are as given below

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With this configurations simulation of Blackhole attacks over the MANET is done

and the third scenario is used to improve the performance of AODV and the

configurations changes made are discussed in the next section

4.4 AODV performance scenario

This scenario is used to improve the performance of AODV under Blackhole

attacks and this scenario is created by duplicating the second scenario.

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Configuration changes are made to AODV routing protocol parameters and

Wireless LAN parameters and they are shown below

Above are change changes made to AODV routing protocol parameters and with

these configurations overall performance of MANET network and AODV is

improved under Blackhole attacks as well. Following are the changes made to

wireless LAN parameters and thus performance of application server is also

improved and thus the overall performance of applications as well

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Once all the three scenarios are created simulation is run for 1 hour and manage

scenarios option is used. Similar performance metrics are used for all the three

scenario and the manage scenario screen is as shown below

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Once the simulation is done results are compared for performance evaluation and a

detailed discussion is done in the next chapter[52,53].

4.5 Running the simulation

Main aim of this simulation is to evaluate and improve performance of AODV

routing protocol under Blackhole attacks. Mobile ad hoc network (MANET) is

simulated using OPNET modeler and three scenarios are created. First scenario has

normal MANET working conditions with AODV routing protocol, second scenario

has Blackhole attacks and third scenario has improved AODV working conditions.

AODV routing protocol parameters and wireless LAN parameters are configured

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to simulate the Blackhole attacks and same parameters are used to improve the

AODV performance and overall network and application performance.

Performance metrics are chosen at AODV, FTP, HTTP and Wireless LAN server

level and the simulation is run for one hour to evaluate the results and they are

discussed in the next chapter[54].