Building Topology in NS3

1. Building Topology
[Part-01]

2. Point-To -Point Topology
<Reading Code>
Node-1 Node-2

3. Flow Chart
Create Node
Attach NetDeive
&
Channel
[NODES]
Install
Protocol Stack
[NODES]
Assign
Ip Address
[NETDEVICE]
Install
Application
[NODES]

4. Node
● Use to create NODE
– To create NODE Object we use Node class with
TEMPLATE function CreateObject<> &
Reference Counting Smart Pointer Ptr<>
Ptr<Node> n= CreateObject<Node>();
● Use of Helper Class
– To create Group of NODE we use NodeContainer
NodeContainer nc;
nc.Create(3);

5. Channel & NetDevice
● It is a logical path over which information flows
– To create Channel we use following classes:-
● WifiChannel
● CsmaChannel
● PointToPointChannel
● Etc...
– To create NetDevice we use following classes:-
● WifiNetDevice
● CsmaNetDevice
● PointToPointNetDevice
● Etc...

6. Channel & NetDevice
● Use of Helper Classes
– We can use Helper Classes:-
● WifiHelper
● CsmaHelper
● PointToPointHelper
● Now ATTACH NetDevice & Channel
– NetDeviceContainer device
– device=pointTopoint.Install(NodeContainer);
● At this point we are done with :-
– NODE
– NetDevice
– Channel
Coupling of NetDevice
with Channel
NetDevice-0 NetDevice-1Point-to-point
Channel
Node-0 Node-1

7. Internet Stack & Ipv4Address
● Now its time to install Protocol Stack
– Helper Class
● InternetStackHelper i
● Now INSTALL protocol stack on Nodes
– i.install(NodeContainer);
● Ipv4Address
– Now associate the devices on our node with IP addresses
● Ipv4AddressHelper iaddr;
● Iaddr.SetBase(“10.1.1.0”,”255.255.255.0”);
– Now assign this IP address to Nodes using Ipv4Interface object
● Ipv4InterfaceContainer iinter = iaddr.Assign(device)
NetDevice-0 NetDevice-1Point-to-point
Channel
Node-0 Node-1
Internet Stack Internet Stack10.1.1.1/24 10.1.1.2/24

8. Application
● Application abstract class
– UdpEchoServerApplication – server
application
– UdpEchoClientApplication -client application
● We use Helper classes
– UdpEchoServerHelper
– UdpEchoClientHelper

9. Server Application
UdpEchoServerHelper server(9);
– Set up a UDP echo server application on one of the node
– Require the port number as a parameter to the constructor
ApplicationContainer serApp;
serApp.Install(nodes.Get(1));
servApp.Start(Seconds(1.0));
servApp.Stop(Seconds(10.0));
– Install server application on Node-1
NetDevice-0 NetDevice-1Point-to-point
Channel
Node-0 Node-1
Internet Stack Internet Stack10.1.1.1/24 10.1.1.2/24
Server App
NetDevice-0 NetDevice-1Point-to-point
Channel
Node-0 Node-1
Internet Stack Internet Stack10.1.1.1/24
Server App

10. Client Application
UdpEchoClientHelper client(i.GetAddress(1),9);
● Pass parameter (to helper) to set the Remote Address and
Remote port for for client to connect.
ApplicationContainer clientApp
=client.Install(nodes.Get(0));
clientApp.Start(Seconds(2.0));
clientApp.Stop(Seconds(9.0));
NetDevice-0 NetDevice-1Point-to-point
Channel
Node-0 Node-1
Internet Stack Internet Stack10.1.1.1/24
Server AppClient App
10.1.1.2/24

11. Start Simulation
Simulation::Run();
Simulation::Destroy();
return 0;
NetDevice-0 NetDevice-1Point-to-point
Channel
Node-0 Node-1
Internet Stack Internet Stack
Server AppClient App

12. Running Example
● Copy program from example to scratch
folder
● And run using following commands
● ./waf --run /scratch/first

13. Simple Modification in
Topology CODE
● Change following values:-
● NetDevice
– DataRate
– Delay
● UDP packet
– MaxPacket
– Interval
– Packet Size

14. ● What is the use of Helper Classes ?
● Why we use Container class ?
● Effect of Packet Size on Rx time @Server ?

15. To be Continued...