28-08-2012, 12:11 PM
QualNet 5.0.2Programmer’s Guide
QualNet-5.0.2-ProgrammersGuide.pdf (Size: 3.48 MB / Downloads: 257)
Introduction
QualNet provides a comprehensive set of tools with all the components for custom network modeling and
simulation projects. QualNet's unparalleled speed, scalability, and fidelity make it easy for modelers to
optimize existing networks through quick model setup and in-depth analysis tools. Models in source form
provide developers with a solid library on which to build and experiment with new network functionality.
The end result is accurate prediction of network performance for a diverse set of application requirements
and uses. From wired LANs and WANs, to cellular, satellite, WLANs and mobile ad hoc networks,
QualNet's library is extensive. Because of its efficient kernel, QualNet models large scale networks with
heavy traffic and mobility in reasonable simulation times.
This chapter gives a brief introduction to the different components of QualNet, and introduces the protocol
stack that forms the basis of QualNet architecture.
QualNet Components
QualNet has several core components, as well as various add-on components. This section provides a brief description of the core components of QualNet. Detailed descriptions, functions, and usage instructions for each of the QualNet components are available in QualNet User’s Guide.
QualNet Simulator
QualNet Simulator is a state-of-the-art simulator for large, heterogeneous networks and the distributed applications that execute on those networks. QualNet Simulator is an extremely scalable simulation engine, accommodating high-fidelity models of networks of tens of thousands of nodes. QualNet makes good use of computational resources and models large-scale networks with heavy traffic and mobility, in reasonable simulation times.
QualNet Simulator has the following attractive features:
•Fast model set up with a powerful Graphical User Interface (GUI) for custom code development and reporting options
•Instant playback of simulation results to minimize unnecessary model executions
•Fast simulation results for thorough exploration of model parameters
•Scalable up to tens of thousands of nodes
•Real-time simulation for man-in-the-loop and hardware-in-the-loop models
•Multi-platform support
QualNet Protocol Stack
QualNet uses a layered architecture similar to that of the TCP/IP network protocol stack. Within that architecture, data moves between adjacent layers. QualNet's protocol stack consists of, from top to bottom, the Application, Transport, Network, Link (MAC) and Physical Layers.
Adjacent layers in the protocol stack communicate via well-defined APIs, and generally, layer
communication occurs only between adjacent layers. For example, Transport Layer protocols can get and
pass data to and from the Application and Network Layer protocols, but cannot do so with the Link (MAC)
Layer protocols or the Physical Layer protocols. This rule concerning communication only between
adjacent layers may be circumvented by the programmer, as explained in Section 4.11.
Network Layer
The Network Layer is responsible for data forwarding and queuing/scheduling. The Internet Protocol (IP) resides at this layer and is responsible for packet forwarding. At the source node, the Network Layer receives data from the Transport Layer and relies on the Link (MAC) Layer for link-by-link data delivery. At the destination node, the Network Layer receives data from the Link (MAC) Layer and passes the data up to the Transport Layer.
The Network Layer also implements certain types of routing protocols. Examples of Network Layer routing
protocols implemented in QualNet are AODV, DSR, OSPF, and DVMRP. Examples of queuing/scheduling
protocols implemented in QualNet are FIFO, RED, RIO, WFQ, and WRR.
Section 4.4 provides implementation details of Network Layer protocols in QualNet and describes how to
develop a custom Network Layer protocol. The following types of protocols are covered in this section:
Network Layer unicast routing protocols, Network Layer multicast routing protocols, queuing protocols, and
schedulers.
Link (MAC) Layer
The Link (MAC) Layer provides link-by-link transmission. At the sending side, the Link (MAC) Layer receives data from the Network Layer and passes the data to the Physical Layer for transmission over the wired or wireless channel. At the receiving side, the Link (MAC) Layer receives data from the Physical Layer and forwards the data up to the Network Layer. Examples of protocols at the Link (MAC) Layer implemented in QualNet are point-to-point, IEEE 802.3, IEEE 802.11, and CSMA.
Section 4.5 provides implementation details of MAC Layer protocols in QualNet and describes how to
develop a custom MAC Layer protocol. Procedures for both wired and wireless MAC protocols are covered
in this section.
Physical Layer
The Physical Layer is responsible for transmitting and receiving raw bits from the wired and wireless channel. At the source node, the Physical Layer receives data from the Link (MAC) Layer and sends the data to the Physical Layer of the destination node. At the destination node, the Physical Layer receives data from the Physical Layer of the source node and passes the data to the Link (MAC) Layer.