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SCHOOL OF COMPUTER SCIENCE AND ENGINEERING
DEPARTMENT OF COMPUTER SCIENCE ENGINEERING
Computer Networks and Design – SCSA1502
Computer Networks and Design – SCSA1502
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Computer Networks and Design – SCSA1502, Lecture notes of Computer Networks
A course outline for Computer Networks and Design – SCSA1502. It covers the fundamentals of network design, underlying LAN concepts, VPNs, intranets and extranets, networking tools and techniques, and evolving technologies. The course objectives include recognizing the principles of the big picture of computer networks, understanding the networking environment, knowing the importance of VPNs, conveying the availability of tools and techniques for networking, and discussing evolving technologies in networks. an overview of network design, the benefits of a hierarchical network design, and network design methodology.
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SCHOOL OF COMPUTER SCIENCE AND ENGINEERING
DEPARTMENT OF COMPUTER SCIENCE ENGINEERING
Computer Networks and Design – SCSA
Computer Networks and Design – SCSA
COURSE OBJECTIVES
To recognize the principles of the big picture of computer networks. To understand the networking environment. To know the importance of VPNs. To convey the availability of tools and techniques for networking. To discuss about evolving technologies in networks. UNIT 1 FUNDAMENTALS OF NETWORK DESIGN 9 Hrs Design Principles - Determining Requirements - Analyzing the Existing Network - Preparing the Preliminary Design - Completing the Final Design Development - Deploying the Network - Monitoring and Redesigning – Maintaining - Design Documentation - Modular Network Design - Hierarchical Network Design. UNIT 2 UNDERLYING LAN CONCEPTS 9 Hrs LAN connectivity for small businesses – Integration – Token-Ring – Ethernet – ATM LAN emulation – InterLAN Switching – LAN to Mainframe – Building networks. UNIT 3 VPNS, INTRANETS AND EXTRANETS 9 Hrs Virtual Network management and planning – VPNs for small businesses – Secure remote access in VPNs – IPSec VPNs – Integrating data centers with Intranets – Implementing and supporting Extranets. UNIT 4 NETWORKING TOOLS AND TECHNIQUES 9 Hrs Simulation method for designing multimedia networks – Determining remote bridge and router delays – Network baselining as a planning tool. UNIT 5 EVOLVING TECHNOLOGIES 9 Hrs Trends in data communications – Merits of xDSL technology – Preparing for cable modems - Voice and video on the LAN – Internet voice applications – Building IP PBX telephony network
- Fax over IP – Videoconferencing over IP networks. Max.45 Hrs.
SCHOOL OF COMPUTER SCIENCE AND ENGINEERING
DEPARTMENT OF COMPUTER SCIENCE ENGINEERING
Computer Networks and Design – SCSA
UNIT I - FUNDAMENTALS OF NETWORK-SCSA
UNIT I
FUNDAMENTALS OF NETWORK DESIGN
Design Principles - Determining Requirements - Analyzing the Existing Network - Preparing the Preliminary Design - Completing the Final Design Development - Deploying the Network - Monitoring and Redesigning – Maintaining - Design Documentation - Modular Network Design - Hierarchical Network Design. INTRODUCTION Network designers ensure that our communications networks can adjust and scale to the demands for new services. To support our network-based economy, designers must work to create networks that are available nearly 100 percent of the time. Information network security must be designed to automatically fend off unexpected security incidents. Using hierarchical network design principles and an organized design methodology, designers create networks that are both manageable and supportable. NETWORK DESIGN CONCEPTS What is the design methodology used by network designers? Network designers ensure that our communications networks can adjust and scale to the demands for new services. To support our network-based economy, designers must work to create networks that are available nearly 100 percent of the time. Information network security must be designed to automatically fend off unexpected security incidents. Using hierarchical network design principles and an organized design methodology, designers create networks that are both manageable and supportable Basics of network design Network design overview The benefits of a hierarchical network design Network design methodology NETWORK DESIGN OVERVIEW Computers and information networks are critical to the success of businesses, both large and small. They connect people, support applications and services, and provide access to the resources that keep the businesses running. To meet the daily requirements of businesses, networks themselves are becoming quite complex. Today, the Internet-based economy often demands around-the-clock customer service. This means that business networks must be available nearly 100 percent of the time. They must be smart enough to automatically protect against unexpected security incidents. These business networks must also be able to adjust to changing traffic loads to maintain consistent application
Schedule - This could include the phasing out of older applications, hiring of new personnel, and so forth. People - Considerations include who will install and operate the network, what skills they have, whether they require training, whether any of these tasks will be outsourced, and so forth. Legal Issues include any restrictions on the use and storage of data collected History Factors include examining the existing network's structure and determining whether any person or group will block changes or additions. Policies Consider whether current organizational policies might restrict the network design. Most businesses actually have only a few requirements for their network The network should stay up all the time, even in the event of failed links, equipment failure, and overloaded conditions. The network should reliably deliver applications and provide reasonable response times from any host to any host. The network should be secure. It should protect the data that is transmitted over it and data stored on the devices that connect to it. The network should be easy to modify to adapt to network growth and general business changes. Because failures occasionally occur, troubleshooting should be easy. Finding and fixing a problem should not be too time-consuming. Building a Good Network Good networks do not happen by accident. They are the result of hard work by network designers and technicians, who identify network requirements and select the best solutions to meet the needs of a business. The steps required to design a good network are as follows Step 1. Verify the business goals and technical requirements. Step 2. Determine the features and functions required to meet the needs identified in Step 1. Step 3. Perform a network-readiness assessment. Step 4. Create a solution and site acceptance test plan. Step 5. Create a project plan. After the network requirements have been identified, the steps to designing a good network are fol- lowed as the project implementation moves forward. Network users generally do not think in terms of the complexity of the underlying network. They think of the network as a way to access the applications they need, when they need them. Network Requirements Most businesses actually have only a few requirements for their network The network should stay up all the time, even in the event of failed links, equipment failure, and overloaded conditions. The network should reliably deliver applications and provide reasonable response times from any host to any host. The network should be secure. It should
protect the data that is transmitted over it and data stored on the devices that connect to it. The network should be easy to modify to adapt to network growth and general business changes. Because failures occasionally occur, troubleshooting should be easy. Finding and fixing a problem should not be too time-consuming. FUNDAMENTAL DESIGN GOALS When examined carefully, these requirements translate into four fundamental network design goals Scalability Scalable network designs can grow to include new user groups and remote sites and can support new applications without impacting the level of service delivered to existing users. Availability A network designed for availability is one that delivers consistent, reliable perform- ance, 24 hours a day, 7 days a week. In addition, the failure of a single link or piece of equipment should not significantly impact network performance. Security Security is a feature that must be designed into the network, not added on after the net- work is complete. Planning the location of security devices, filters, and firewall features is critical to safeguarding network resources. Manageability No matter how good the initial network design is, the available network staff must be able to manage and support the network. A network that is too complex or difficult to maintain cannot function effectively and efficiently. NETWORK DESIGN Implementation Components Implementation of a network design consists of several phases (install hardware, configure systems, launch into production, and so on). Each phase consists of several steps, and each step should contain, but be not limited to, the following documentation Description of the step Reference to design documents Detailed implementation guidelines Detailed roll-back guidelines in case of failure Estimated time needed for implementation Analysing the Existing Network The second step of the design methodology is characterizing the existing network and sites The following sections present insights into the process of examining an existing network and sites and describe the tools used to gather the data, assess the network, and analyze the network. Customer input Review existing documentation about the network, and use verbal input from the customer to obtain a first impression about the network Network audit Perform a network audit, also called an assessment, which reveals details of the network and augments the customer’s description Traffic analysis If possible, use traffic analysis to provide information about the applications and protocols used and to reveal any shortcomings in the network. Customer input includes all pertinent network and site documentation.
(Both the preliminary design and final design are done Using PDIOO) FOLLOWING A DESIGN METHODOLOGY CAN HAVE MANY ADVANTAGES It ensures that no step is missed when the process is followed It provides a framework for the design process deliverables It encourages consistency in the creative process, enabling network designers to set appropriate deadlines and maintain customer and manager satisfaction. It allows customers and managers to validate that the designers have thought about how to meet their requirements Preliminary Design Step involves in the preparation of detailed Documentation of the network It is achieved by collecting information from customer, inspecting the site, and accessing the network using Automated Tools Different Approaches
1. Top Down Approach A top-down approach to network design means that requirements are considered first, with the applications and network solutions that will run on the network driving the design Figure 2 Top-Down Approach Bottom- Up Approach A bottom-up approach would first select devices, features, cabling, and so on, and then try to fit the applications onto this network Issues in Bottom-Up Approach A bottom-up approach can lead to redesign if the applications are not accommodated properly. This approach can also result in increased costs by including features or devices that are not required A bottom-up approach would first select devices, features, cabling, and so on, and then try to fit the applications onto this network
Figure 3 Bottom-Up Approach Issues in Bottom-Up Approach A bottom-up approach can lead to redesign if the applications are not accommodated properly. This approach can also result in increased costs by including features or devices that are not required THE BENEFITS OF A HIERARCHICAL NETWORK DESIGN To meet the four fundamental design goals, a network must be built on an architecture that allows for both flexibility and growth. Hierarchical Network Design In networking, a hierarchical design is used to group devices into multiple networks. The networks are organized in a layered approach. The hierarchical design model has three basic layers Core layer Connects distribution layer devices Distribution layer Interconnects the smaller local networks Access layer Provides connectivity for network hosts and end devices Hierarchical networks have advantages over flat network designs. The benefit of dividing a flat network into smaller, more manageable hierarchical blocks is that local traffic remains local. Only traffic destined for other networks is moved to a higher layer. Layer 2 devices in a flat network provide little opportunity to control broadcasts or to filter undesirable traffic. As more devices and applications are added to a flat network, response times degrade until the network becomes unusable. Figures 1-1 and 1-2 show the advantages of a hierarchical network design versus a flat network design. Figure 4 Flat Network
separately. It provides scalability by allowing enterprises to add modules easily. As network complexity grows, the designer can add new functional modules. It enables the designer to add services and solutions without changing the underlying network design. Figure 7 Enterprise Campus Interactive Activity 1-1 Match the Characteristics of the Hierarchal Model and the Cisco Enterprise Architecture (1.1.2) In this interactive activity, you match the characteristics of the hierarchal model and the Cisco Enterprise Architecture to their correct location. Use file ia- 112 on the CD-ROM that accompanies this book to perform this interactive activity NETWORK DESIGN METHODOLOGIES Large network design projects are normally divided into three distinct steps Step 1. Identify the network requirements. Step 2. Characterize the existing network. Step 3. Design the network topology and solutions. Step 1 Identifying Network Requirements The network designer works closely with the customer to document the goals of the project. Figure 1-5 depicts a meeting between the designer and the business owner. Goals are usually separated into two categories Business goals Focus on how the network can make the business more successful Technical requirements Focus on how the technology is implemented within the network Step 2 Characterizing the Existing Network Information about the current network and services is gathered and analysed. It is necessary to compare the functionality of the existing network with the defined goals of the new project. The designer determines whether any existing equipment, infrastructure, and protocols can be reused, and what new equipment and protocols are needed to complete the design. Step 3 Designing the Network Topology A common strategy for network design is to take a top-down approach. In this approach, the network applications and service requirements are identified, and then the network is
designed to support them. When the design is complete, a prototype or proof-of-concept test is performed. This approach ensures that the new design functions as expected before it is implemented. Figure 8 Enterprise Campus A common mistake made by network designers is the failure to correctly determine the scope of the network design project. Determining the Scope of the Project While gathering requirements, the designer identifies the issues that affect the entire network and those that affect only specific portions. By creating a topology similar to Figure 1-6, the designer can isolate areas of concern and identify the scope of the project. Failure to understand the impact of a particular requirement often causes a project scope to expand beyond the original estimate. This oversight can greatly increase the cost and time required to implement the new design.
Monitoring and Redesigning Phase After the network is operating, baseline operational statistics should be gathered so that working status can be identified The network should then be monitored for anomalies and problems. If problems occurs, or if requirements change or are added, then appropriate design changes must be made and the entire design process should be repeated for that portion of the network. Note Monitoring and redesign take place in the PDIOO Operate and Optimize phases, and can lead back into the Plan and Design phases. Maintaining Design Documentation The design should be documented throughout the process. Documentation should include the following items All the agreed-to requirements and constraints The state of the existing network, if any Preliminary design options and a brief review of why the final design was chosen Final design details Results of any pilot or prototype testing Deployment plans, schedules, and other implementation details Monitoring requirements Any other pertinent information A module is a component of a composite structure Modular network design involves creating modules that can then be put together to meet the requirements of the entire network. A modular design for a network has many benefits, such as It is easier to understand and design smaller, simpler modules rather than an entire network It is easier to troubleshoot smaller elements compared to the entire network The reuse of blocks saves design time and effort, as well as implementation time and effort The reuse of blocks allows the network to grow more easily, providing network scalability It is easier to change modules rather than the entire network, providing flexibility of design.
TEXT/ REFERENCE BOOKS
- Gil Held, “Network Design: Principles and Applications (Best Practices)”, Auerbach Publications, 1st edition, 2000.
- Diane Tiare and Catherine Paquet, “Campus Network Design Fundamentals”, Pearson Education, 1st edition, 2006.
- Larry L. Peterson, Bruce S. Davie, “Computer Networks: A Systems Approach”, Morgan Kaufmann Publishers Inc., 5th^ edition, 2012.
- William Stallings, “Data and Computer Communications”, Pearson Education, 8th edition,
- James F. Kurose, Keith W. Ross, “Computer Networking - A Top-Down Approach Featuring the Internet”, Pearson Education, 6th edition, 2012. PART A- 2 MARK QUESTIONS S.NO QUESTIONS CO LEVEL 1 Identify the design methodology used by network designers? CO1 3 2 List the technical requirements of computer network. CO1 4 3 Discuss the steps required to design a good network. CO1 6 4 Examine various fundamental design goals in the network. CO1 4 5 Identify various design principles applicable to network. CO1 3 6 Summarize the benefits of PDIOO Cycle. CO1 2 7 List the requirements related to business Issues in the computer network.
CO1 4
8 Show the PDIOO life cycle Diagram. CO1 1 9 How refer design documents explain briefly. CO1 1 10 List the Network design task and explain briefly. CO1 1 PART B- 10 MARK QUESTIONS S.NO QUESTIONS CO LEVEL 1 Analyzing the existing network and explain briefly for each steps. CO1 4 2 Discuss the preparing for preliminary design with neat diagrams. CO1 6 3 Discuss the preparing for final design document, Monitoring, Designing and Maintaining Design Documentation.
CO1 6
4 Explain hierarchical network design with neat diagram and write the comparison of flat and hierarchical network.
CO1 5
5 Explain Modular Network Design with examples and also write the benefits of modular network design.
CO1 5
UNIT II
UNDERLYING LAN CONCEPTS
LAN connectivity for small businesses – Integration – Token-Ring – Ethernet – ATM LAN emulation – InterLAN Switching – LAN to Mainframe – Building networks. NETWORKS A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. Distributed Processing Most networks use distributed processing, in which a task is divided among multiple computers. Instead of one single large machine being responsible for all aspects of a process, separate computers (usually a personal computer or workstation) handle a subset. Network Criteria A network must be able to meet a certain number of criteria. The most important of these areperformance, reliability, and security. Performance Performance can be measured in many ways, including transit time and response time.Transit time is the amount of time required for a message to travel from one device to another. Response time is the elapsed time between an inquiry and a response. The performance of a network depends on a number of factors, including the number of users, the type of transmission medium, the capabilities of the connected hardware, and the efficiency of the software. Performance is often evaluated by two networking metrics throughput and delay. We often need more throughput and less delay. However, these two criteria are often contradictory. If we try to send more data to the network, we may increase throughput but we increase the delay because of traffic congestion in the network. Reliability In addition to accuracy of delivery, network reliability is measured by the frequency of failure, the time it takes a link to recover from a failure, and the network's robustness in a catastrophe. Security Network security issues include protecting data from unauthorized access, protecting data from damage and development, and implementing policies and procedures for recovery from breaches and data losses. PHYSICAL STRUCTURES Type of Connection
A network is two or more devices connected through links. A link is a communications pathway that transfers data from one device to another. For visualization purposes, it is simplest to imagine any link as a line drawn between two points. For communication to occur, two devices must be connected in some way to the same link at the same time. There are two possible types of connections point-to-point and multipoint. Point-to-Point A point-to-point connection provides a dedicated link between two devices. The entire capacity of the link is reserved for transmission between those two devices. Most point-to-point connections use an actual length of wire or cable to connect the two ends, but other options, such as microwave or satellite links, are also possible. When you change television channels by infrared remote control, you are establishing a point-to-point connection between the remote control and the television's control system. Multipoint A multipoint (also called multidrop) connection is one in which more than two specific devices share a single link. In a multipoint environment, the capacity of the channel is shared, either spatially or temporally. If several devices can use the link simultaneously, it is a spatially shared connection. If users must take turns, it is a timeshared connection. Figure 10 Types of connection PHYSICAL TOPOLOGY The term physical topology refers to the way in which a network is laid out physically. One or more devices connect to a link; two or more links form a topology. The topology of a network is the geometric representation of the relationship of all the links and linking devices (usually called nodes) to one another. There are four basic topologies possible mesh, star, bus, and ring