• Applications are the sources of traffic in the network. This traffic is modeled as individual packets. 
  • These packets flow from the source to the destination over the designed network. As it flows through the network, depending on the devices, link bandwidths, and networking protocols, the packets would experience network effects such as delay, error, loss, etc.
  • Applications are generally parameterized in terms of packet size, inter-packet arrival time, priority, transport protocol running below, etc. 
  • Each application has its own distinctive traffic pattern and creates its own unique load on the network.
  • NetSim allows users to model and simulate different types of applications like CBR, Custom, FTP and HTTP, etc.


In this example, we explain the parameter settings for getting the same throughput for CBR and FTP applications. Note that:

  • In CBR Application we configure the Packet-size. 
  • Whereas in FTP we configure the File-size.
  • Traffic Generation Rate for CBR.

                                  Generation Rate (Mbps) =(Packet Size (bytes) * 8)/ Inter arrival Time(micro sec)

                       

  • For FTP

                                   Generation Rate (Mbps) =(File Size (bytes) * 8)/ Inter arrival Time(sec)


  • If we want to configure 'equivalently' for both CBR and FTP applications, then for what ever the FTP-IAT and FTP-File-Size set, the CBR settings should be


    CBR-Packet-Size(Bytes) = 1460 
    CBR-Inter-arrival_time (mircoseconds) = (1460 * 1,000,000 * FTP-IAT(seconds) /FTP-File-Sie (B))


Case 1 - For FTP Application 

  • Network Scenario:
  • Application Settings

    Application Properties

    Application Type

    FTP

    Source ID

    1

    Destination ID

    2

    Transport Protocol

    UDP

    Packet Size

    1,250,000 Bytes

    IAT

    5 sec



Case 2 - For CBR Application

  • Network Scenario:
  • Application Settings: 
    • CBR IAT = (1460 * 1,000,000 * 5 / 1,250,000)

Application Properties

Application Type

CBR

Source ID

1

Destination ID

2

Transport Protocol

UDP

Packet Size

1460 Bytes

IAT

5840 micro sec


  • Simulation time is 100 sec for both cases


Results Comparison for CBR and FTP Applications: You will get approximately the same throughput if you run the simulation for a long time. There will be a small difference because in FTP the entire file is generated in the beginning but in CBR packets are generated every IAT 


Application Type

Throughput (Mbps)

CBR

1.99

FTP

1.99