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…

Security Protocol (packet) in NS2

Security is not my area of work, but most of the places, I have been bombarded with questions like , is it possible to implement security protocol in ns2.
The answer is yes, here is the solution for that.  Here is the document to read
This work is done in 2005 and developed for ns version 2.26 or 2.27. I have done the compilation for ns-2.35
The files to be modified
1. Create a new agent called "Security_packet" and two files Security_packet.h and Security_packet.cc are created.
2. Add a new packet type in ~ns-2.35/common/packet.h
3. Add a new packet type in ~ns-2.35/tcl/lib/ns-default.tcl
4. Add a new packet type in ~ns-2.35/tcl/lib/ns-packet.tcl
5. modify the ~ns-2.35/Makefile.in

1. Download the two files here
2. Copy the security.cc and security.h file in ~ns-2.35/security folder (create the security/ folder and paste both the files)
3. Open ~ns-2.35/Makefile.in and make an entry as shown below,

4. Open the ~ns-2.35/common/packet.h file
There will be two changes
Change one
static const packet_t PT_SECURITY_PACKET=74;
as shown below
and another change
name_[PT_SECURITY_PACKET]= "Security_packet";
as shown below


5. Open the file ~ns-2.35/tcl/lib/ns-default.tcl, and paste the following line at the end of the file
Agent/Security_packet set packetSize_ 0

See below
6.  open the file ~ns-2.35/tcl/lib/ns-packet.tcl, Input the following line 
as shown below

To Compile

Open the terminal, 
$] cd ~ns-allinone-2.35/ns-2.35/
$] ./configure
$] make

Run the security.tcl file using the ns command 
$] ns security.tcl

See the output, Since my area is not on the security, read the document/source code yourself

Thats it!!!

T S Pradeep Kumar

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