NETWORK SIMULATION TOOLS

• NS2
• NS3
• OMNET ++
• OPNET
• QUALNET
• PSIM
• PEER SIM

Architecture of a Node in NS2 PROJECT
id_ Node ID
agents_ List of attached transport layer agents
nn_ Total number of Nodes (a static class instvar belonging to
an OTcl class Node)
neighbor_ List of neighboring nodes
nodetype_ Node type (e.g., regular node or mobile node)
ns_ Simulator
dmux_ Demultiplexer or port classifier
module_list_ List of enabled routing modules
reg_module_ List of registered routing modules
rtnotif_ List of routing modules which will be notified of route up-
dates
ptnotif_ List of routing modules which will be notified of port at-
tachment/detachment
hook_assoc_ Sequence of the chain of classifiers
mod_assoc_ Association of classifiers and routing modules, whose in-
dexes and values are classifiers and the associated routing
modules, respectively.

The routing mechanism in NS2 PROJECTconsists of four main components:
• Routing agent: collects information (e.g., the network topology) needed to compute a routing
• Route logic: uses the information collected by the routing agent, and compute the routing table.
• Classifier: employs the computed routing table for packet forwarding.
• Routing module: acts as a single point of management of a group of classifiers in a Node.It takes configuration commands from a routing agent a route logic, and a Node, and propagates them to relevant classifiers.