Computer Networks PDF

Computer Networks What’s Ahead? Build an understanding of the fundamental concepts of computer networking. Familiarize the student with the basic taxonomy and terminology of the computer networking area. Prepare yourself for entry in the advanced courses in computer networki...

Computer Networks What’s Ahead? Build an understanding of the fundamental concepts of computer networking. Familiarize the student with the basic taxonomy and terminology of the computer networking area. Prepare yourself for entry in the advanced courses in computer networking. Gain expertise in some specific areas of networking such as the design and maintenance of individual networks. Computer Network Computer Network A computer network is a collection of computing devices that are connected in various ways to communicate and share resources. Usually, the connections between computers in a network are made using physical wires or cables. However, some connections are wireless, using radio waves or infrared signals. Computer Network Why Networking? Computer networking method in which multiple computers across different locations share computer- processing capability: 1. Sharing information — i.e. data communication 2. Sharing hardware or software 3. Centralize administration and support Distributed processing offers several advantages such as lower cost, reliable, improved performance and reduced processing time, and flexible (geographical locations). Computer Network What is Protocol? Protocol is a set of guidelines for implementing networking communications between computers. Computer Network Networking Layers Computer Network What is Message Encapsulation? In computer networking, encapsulation is a method of designing modular communication protocols in which logically separate functions in the network are abstracted from their underlying structures by inclusion or information hiding within higher level objects. Computer Network What is OSI? OSI stands for Open Systems Interconnection ▪ provides a general framework for standardization ▪ defines a set of layers and services provided by each layer ▪ one or more protocols can be developed for each layer Computer Network What is TCP/IP? TCP stands for Transmission Control Protocol TCP software breaks messages into packets, hands them off to the IP software for delivery, and then orders and reassembles the packets at their destination IP stands for Internet Protocol IP software deals with the routing of packets through the maze of interconnected networks to their final destination. Computer Network Networks A network is a set of devices connected by communication links. The Internet is a collaboration of more than hundreds of thousands of interconnected networks. Computer Network What is Topology? The pattern of interconnection of nodes in network is called the topology. Factors to Consider while making a Topology Choice: ▪ Cost ▪ Reliability ▪ Flexibility Computer Network Common Network Topologies BUS All networked nodes are interconnected, peer to peer, using a single, open-ended cable. Both ends of the bus must be terminated with a terminating resistor to prevent signal bounce. Computer Network Common Network Topologies Advantages: 1. Easy to implement and extend 2. Well suited for temporary networks that must be set up in a hurry 3. Typically the least cheapest topology to implement 4. Failure of one station does not affect others Disadvantages: 1. Difficult to administer/troubleshoot 2. Limited cable length and number of stations 3. A cable break can disable the entire network; no redundancy 4. Maintenance costs may be higher in the long run 5. Performance degrades as additional computers are added Computer Network Common Network Topologies STAR Have connections to networked devices that “radiate” out from a common point Each networked device in star topology can access the media independently. Have become the dominant topology type in contemporary LANs. Stars have made buses and rings obsolete in LAN topologies Computer Network Common Network Topologies Advantages: 1. Compared to Bus topology it gives far much better performance 2. Easy to connect new nodes or devices 3. Centralized management. It helps in monitoring the network 4. Failure of one node or link doesn’t affect the rest of network Disadvantages: 1. If central device fails whole network goes down 2. The use of hub, a router or a switch as central device increases the overall cost of the network 3. Performance and as well number of nodes which can be added in such topology is depended on capacity of central device Computer Network Common Network Topologies RING Started out as a simple peer-to- peer topology. Each networked workstation had two connections: one to each of its nearest neighbors. Data was transmitted unidirectional around the ring. Sending and receiving of data takes place by the help of TOKEN. Computer Network Common Network Topologies Advantages: 1. This type of network topology is very organized 2. Performance is better than that of Bus topology 3. No need for network server to control the connectivity between workstations 4. Additional components do not affect the performance of network 5. Each computer has equal access to resources Disadvantages: 1. Each packet of data must pass through all the computers between source and destination, slower than star topology 2. If one workstation or port goes down, the entire network gets affected 3. Network is highly dependent on the wire which connects different components Computer Network Common Network Topologies PEER TO PEER A peer-to-peer can be developed using leased private lines or any other transmission facility. This topology is a relatively simple way of interconnecting a small number of sites. Represents the least- cost solution for that contain a small number of internetworked locations Computer Network Common Network Topologies Advantage: 1. It is inexpensive relative to other options Disadvantages: 1. They don’t scale very well. As additional, the number of hops between any given pair of locations remains highly inconsistent and has an upward trend 2. An equipment or facility failure anywhere in a peer-to-peer Computer Network Common Network Topologies MESH This topology features the ultimate reliability and fault tolerance. Every networked node is directly connected to every other networked node. Redundant routes to each location are plentiful, hence static routing impractical. Use dynamic routing protocols. One application would be to provide interconnectivity for a limited number of routers that require high network availability. Computer Network Common Network Topologies Advantages: 1. Minimizes the number of hops between any two network-connected machines 2. Can be built with virtually any transmission technology Disadvantages: 1. These can be fairly expensive to build 2. A finite (although substantial) limit on the scalability of the network Computer Network Common Network Topologies PARTIAL-MESH TOPOLOGY Partial meshes are highly flexible topologies that can take a variety of very different configurations. The routers are much more tightly coupled than any of the basic topologies but are not fully interconnected, as would be the case in a fully meshed network. A partially meshed WAN topology is readily identified by the almost complete interconnection of every node with every other node in the network. Computer Network Exercise 1. A novice network technician needs to connect the following devices together to create a new network segment. ▪ 3 workstations ▪ a server ▪ a printer ▪ a hub (for a star topology only) He is unsure how to proceed and has asked you to draw the devices arranged in different topologies 2. Illustrate this network by drawing a diagram. Ensure you show all devices. Label and annotate your diagram appropriately and explain the function of the hub, switch and bridge.