Queuing Models in NS2

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…

Data Types in C Programming

Declaration of variable names does two things
  • it tells the compiler what the variable name is
  • specifies what type of data the variable will hold
So it is mandatory that each variable should belong to a particular data type. C supports different data types like integer, character, float, double, etc.
Data type Size on a 16 bit machine Range
char 1 byte or 8 bits -128 to 127
signed char 1 byte -128 to 127
unsigned char 1 byte 0 to 255
short int or short 1 byte -128 to 127
int 2 bytes -32768 to 32767
unsigned int 2 bytes 0 to 65535
long int or long 4 bytes -2,147,483,648 to 2,147,483,647
unsigned long int 4 bytes 0 to 4,294,967,295
float 4 bytes 3.4E-38 to 3.4 E+38
double 8 bytes 1.7E-308 to 1.7E+308
long double 10 bytes 3.4E-4932 to 1.1E+4932
Example of declaring variables
int a=20,b=20,c;
int a=10;
int b=9;
int c=20;
float c=3.5;
char a =’A’;
long int al or long a;
short int b or short b;
double c;
long double c;

 T S Pradeep Kumar

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