|PET-SIM is the networking tool developed inhouse using C and Tcl language with certain objectives as given below.
To provide an interactive interface to NS (network simulator) package for building network topology.To conduct performance study of given network topology such as bandwidth utilization, packet losses, throughput, packet delays and delay-jitter.To view the working of designed topology graphically with aid of nam package
of NS.To study the feasibility of multimedia network topology construction with the given network resources: link capacities, propagation delays and buffers etc.
Features of PETSIM :Provides easy use of NS tool for users unaware of NS commands and Tcl language.Provides option to enter the topology and its resources through interactive or file mode.Users can enter network topology, link capacities, applications (TCP and UDP based) between nodes, scheduling and ending time of applications.Facilitates to view the movement of packets, dropped packets in the network in an animated manner.
Framework of PET-SIM :
The PET-SIM construction and its working is depicted in the following figure.
It consists of an user interface which takes input from users about the topology and the network resources either through keyboard or file. The gathered topology and the network resources are passed on to a Tcl program which executes NS commands to run the topology. At the same time it generates out.tr (trace file consisting of information about the packet sequence numbers, drops, type of packet etc.,) and out.nam (network animation file for viewing animation of network).
It also displays nam file and the performance parameters of the topology. If a user is intrested in calculation of performance parameters, he can calculate using out.tr file.
Topology can be entered in a file as given in the following example. Consider 3 nodes, with links 1-2 and 2-3 with capacities 2 mbps, 1.5 mbps respectively. Run an FTP application between nodes 1-3.
Entries in file will be,
3 number of nodes in topology
1 2 2 define link 1-2 and its capacity
1 another link to be defined
2 3 2 define link 2-3 and its capacity
0 no more links to be defined
0 define FTP session
1 3 session between 1 and 3 nodes
0 3 starting and ending time of application
0 no more application to be given