Analyzing And Modeling Of Communication Network

Published Date: 02 Nov 2017

OPNET (Optimized Network Engineering Tools) is a comprehensive software environment for modeling, simulating, and analyzing the performance of communication networks (including the internet). Recent articles [Cheng, 1-Vukadinovic, 7] have described how OPNET has been used. OPNET features include object oriented editors that mirror the structure of actual networks, and support of most network types and technologies. OPNET has become the industry standard tool for designing networks, and evaluating network performance under various test conditions

Today the field of computer networks all over the world has entered an exponential growth phase. These demands have made the necessity of capable network engineers extremely covet. An invaluable tool in this case consists of the network simulator OPNET Modeler that offers the tools for model design, simulation, data mining and analysis for, considering the alternatives, a reasonable cost. OPNET Modeler can simulate a wide variety of different networks which are link to each other.

Background of the problem

Industry studies have repeatedly shown that configuration errors are a major source of network downtime, degraded performance, and gaps in network security. Maintaining network integrity and security is imperative for ensuring quality service, demonstrating regulatory compliance, and mitigating risks. However, the sheer number and diversity of devices in the network make the task of identifying problem configurations intractable. These problems made me to study on the above topic

Statement of the problem

A company that has a local area network (LAN) on a first floor office building, and plans to add an additional network on another floor. To develop a model of a company's wide area network(WAN). The models are used to study how the performance of the network is affected by the different design decisions that are made to upgrade the network. And effect the different network configurations on different protocols. This problem made me to analyze and model the communication network using OPNET to provide industry a best performance network design.

Research questions to be answered

The key to network modeling is the ability to closely match the generated network model map to the real network topology. We wanted to find out how accurately each product modeled events such as link failure, link change, device failure, load change, route change and link overloading will effect by different configurations on different protocol

Statement of hypothesis or research objectives

To find out the Mechanism of network modeling, Modeling Accuracy, Basic Methods/ Algorithms for analyzing communication network and to Analyze and model (LAN and WAN) based on OPNET using different protocols with various configurations.

Importance of the study

The context of this research is to analyze and model communication network using OPNET. The models are used to study how the performance of the network is affected by the different design decisions that are made to upgrade the network. And effect the different network configurations on different protocols.

Scope and delimitations of the study

This research helps me to check the entire network, diagnosing device misconfigurations, errors, policy violations, and inefficiencies. To understand powerful modeling platform and also inherent understanding of topology and routing to detect network-level issues. The limitations of this study is strict to Ethernet Simulation, TCP simulation, OSPF Simulation and Queuing policies

Selection of subjects

Subjects included are:

Communication network analyzing and modeling based on OPNET.

Basic method of communication network analyzing

Mechanism of network modeling

System modeling of communication network

OPNET modeling and analyzing

Simulative experiment and analyzing of communication network modeling based on OPNET

Research design

The nature of study is Explanatory. Study is limited to analyze and model the communication networks using OPNET Modeler 9.0 and OPNET IT GURU 10.5

To accomplish this research I prefer to follow the Quasi-experimental approach. The solution can be found by experiment and some correlation study

Literature Review

This part of research introduces to OPNET, and how to use OPNET to build and analyze network models. OPNET is a modeling and simulation tool [MIL31] that provides an environment for analysis of communication networks. The tool provides a three layer modeling

hierarchy. The highest layer referred to as the network domain allows definition of network topologies. The second layer referred to as the node domain allows definition of node architectures (data flow within a node). The third layer (process domain) specifies logic

or control flow among components in the form of a finite state machine.

Analysis of a LAN scenario.

Researcher will learn about LAN networks by solving the problems they are asked to do in a LAN scenario . They will understand how a LAN protocol works and calculate its performance: i.e. Aloha, CSMA/CD, etc. First they will find statistics about the throughput of network protocol (S) as function of G (traffic offered), the access time and again the throughput as function of the parameter a changing either the diameter of the network or the bit rate.

After being analyzed such topics they will work extensively in Ethernet technologies learning the different versions of an Ethernet network: half or full duplex, switched, etc. And they will also improve the proposed scenario by designing a new LAN network by modifying the previous topology adding equipment such bridges, switches, etc. Finally they should analyze the performance achieved by their design.

In this research, the basic model is a hypothetical company’s LAN (local area network) on a first floor office building (See Figure 1). The 30 nodes represent workstations that are linked to a database server via a switch. The Applications object in the figure specifies the application traffic (e.g. database access, e-mail, web browsing, and file transfer) that can exist in the network. The Profiles object specifies the user profiles that can be modeled in the network. The user profile modeled in this network is database access (light) - workstations accessing the database server at a low rate. The company plans to add an additional network on another floor. The researcher configure the simulator to collect the following statistics for the first floor network: the database server’s Ethernet load and the entire network’s Ethernet delay. After the first network’s statistics are collected, the researcher expand the network model to include a second floor segment which consists of a 30-workstation star topology which is similar to the first network. The second floor network does not have a database server; it is connected to the first floor database server via a router. After the expanded network model is completed, researcher collect statistics (the database server’s Ethernet load and the entire network’s Ethernet delay), and compare them with previous statistics that were collected for the first network. The statistics are used in determining if the database server will be able to handle the additional load of a second network, and if the total delay across the final network will be acceptable once the second network is installed.

WAN Modeling

The basic model in this research is a hypothetical company’s WAN (wide area network). The company has subnets in its offices in Atlanta, Dallas, Denver, and Minneapolis. All the offices are connected to the Internet via 56K point-to-point protocol (PPP) links (Figure 2). The network model also includes profiles of the following types of users and their locations: Engineers – Atlanta and Denver offices, Researchers – Minneapolis office, and Salespersons – Dallas office. The model makes use of the following profiles that have been defined by OPNET: engineers – light web browsing, light e-mail use, light telnet use, and light file transfer; researchers – heavy web browsing and light e-mail use. e-commerce customer – light web browsing; and sales persons – light database access, light e-mail use, light web browsing, and light file printing. The applications (e.g. web browsing) are supported by servers in the Atlanta office (Figure 3).

Network Modeling Using OPNET

OPNET is among the leading discrete event network simulators used both by the commercial and research communities. It provides a comprehensive framework for modeling wired as well as wireless network scenarios. Simulation models are organized in a hierarchy consisting of three main levels: the simulation network, node models and process models. The top level refers to the simulation scenario or simulation network. It defines the network layout, the nodes and the configuration of attributes of the nodes comprising the scenario. The node models are at the second level in the hierarchy and consist of an organized set of modules describing the various functions of the node. The modules in the nodes are implemented using process models, the lowest level in the hierarchy. Process models consist of finite state machines, definitions of model functions, and a process interface that defines the parameters for interfacing with other process models and configuring attributes. Finite state machine models are implemented using Proto C, which is a discrete event library based on C functions. The hierarchal structure of the models, coupled with support for C language programming, allows for easy development of communication or networking models.

OPNET Modeler uses an object-oriented approach for the development of models and

simulation scenarios. The models can be identified as a CLASS, which can be reused any

number of times in the simulation by creating its different instantiations, just like the creation of objects in any object-oriented programming language. Besides allowing the creation of multiple instances, OPNET allows the user to extend the functionality of the basic models already available as part of the model library. Thus, by defining the value of the attributes of the basic model the user can develop customized models following particular standards or vendor specifications.

Basic methods of communication networks is not limited to ATM or TCP …… But many are more included

Asynchronous transfer mode (ATM) is the new generation of computer and communication networks that are being deployed throughout the telecommunication industry as well as in campus backbones. ATM technology distinguishes itself from the previous networking protocols in that it has the latest traffic management technology and thus allows guaranteeing delay, throughput, and other performance measures. This in turn allows users to integrate voice,

video, and data on the same network. Available bit rate (ABR) service in ATM has been designed to fairly distribute all unused capacity to data traffic and is specified in the ATM Forum’s Traffic Management (TM4.0) standard. This research will describe the OPNET models that have been developed for ATM and ABR design and analysis.

The OPNET ATM Model Suite

The OPNET ATM model suite (AMS) described in [MIL32] supports many of the characteristics of ATM networks. The model suite provides support for signaling, call setup and teardown, segmentation and reassembly of cells, cell transfer, traffic management and buffer management. Standard ATM nodes such as routers, stations, bridges, switches etc. are provided to facilitate building of common topologies used for the design and analysis of ATM networks. Traffic management within AMS incorporates functions such as call admission control, policing using a continuous-state leaky bucket implementation (GCRA), call-based queuing, priority scheduling and collection of standard statistics such as end-to-end delay and end-to-end delay variation.

Reference Topology

The example network topology used for the design and development of traffic management functions within AMS represents an N-source configuration shown in Figure 1. Source and destination end-systems are connected to a pair of ATM switches that communicate

via a bottleneck link. The node architecture for the end-system (source/destination) consists of AAL clients sending/receiving traffic to/from the AAL/ATM/PHY protocol stack. The AAL layer is responsible for segmentation of data traffic into AAL PDU’s. The ATM layer (represented as four modules: management, layer, translation and switching) encapsulates the AAL PDU within the ATM cell and transmits the cell to the network. The management module is responsible for signaling. The translation module receives incoming traffic and directs it to the higher layer or back to the network based on the destination address. Figure 1The OPNET ATM Model

Instrumentation.

Operational Instruments : OPNET Modeler 9.0 and OPNET IT Guru 10.5

Resources Needed and available

Opnet Technologies' IT Guru 10.5 and OPNET Modeler 9.0

Approval of study from Department. Offsite help from experts who has experience on OPNET domain.

Projected Start and Completion Date: January 15th 2006 to February 28th 2006