Queuing Models in NS2

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M/M/1 is a system with poisson arrival time, servicing exponentially and a queue of unlimited capacity and type of FIFO Queue. This is the simplest queuing system.  NS2 supports various distributions like pareto, exponential, constant, unifrom, etc to handle the network dynamics and metrics. So it is very easy to test the given network link to monitor a given queue using any of these queuing models. The listing 3 and 4 are monitoring the link when DropTail queue is used with a capacity of finite and infinite. Listing 13.3 uses infinite capacity and Listing 13.4 uses Finite capacity The output screen shot is shown below the scripts for further understanding
Listing 3 – M/M/1 Queuing Model #new Simulator creation set ns [new Simulator] #trace file creation for capturing the UDP data set tf [open out.tr w] $ns trace-all $tf
#setting the exponential distribution param set lambda 30.0 set mu     33.0
#creation of nodes set n1 [$ns node] set n2 [$ns node] #The queue limit is 1Lakh as the capacity is infin…

cbrgen and setdest in NS2 (Network Simulator 2)

This post will help you to understand the automatic TCL code generation for creating connections between the nodes, to create hops, generates tcp or cbr agents, etc.

There are two things are used: setdest and cbrgen.tcl

setdest is used to

  • Create hops between the nodes using the GOD (General Operations Director) object.
  • Create mobility for nodes in terms of metres/second
  • Move from one place to another place using setdest (Set destination) with speed
  • To execute, use ./setdest
Example of Setdest is

$] cd /home/pradeepkumar/ns-allinone-2.35/ns-2.35/indep-utils/cmu-scen-gen/setdest

$] ./setdest -v 2 -n 10 -s 1 -m 10 -M 50 -t 30 -P 1 -p 1 -x 500 -y 500 > usersetdest.tcl

The above output is redirected to usersetdest.tcl 

cbrgen.tcl 
  • create connections between the nodes , one can specify the maximum number of connections to be made for all the nodes in the network
  • to create the type of agents between the nodes (cbr or tcp)
  • rate at which the packets are transmitted.
  • to execute this, ns cbrgen.tcl

Example of cbrgen.tcl is
$] /home/pradeepkumar/ns-allinone-2.35/ns-2.35/indep-utils/cmu-scen-gen
$] ns cbrgen.tcl -type cbr -nn 10 -seed 1 -mc 5 -rate 5.0 > cbr-10-test.tcl
See the image below to use these two scripts

If you want the step by step instruction, refer this video


T S Pradeep Kumar

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