Introduction to network design and management.pdf

NETWORK DESIGN AND MANAGEMENT COSC 404 Network Design and Management Network design and management is of critical and growing importance in business, government and other organizations. Needs to be managed for effectiveness and efficien...

NETWORK DESIGN AND MANAGEMENT COSC 404 Network Design and Management Network design and management is of critical and growing importance in business, government and other organizations. Needs to be managed for effectiveness and efficiency. This study session discusses fundamental aspects of network administration. Network design and management is a branch of engineering that concerns the operational management of human–computer systems. An act of putting together a network of computers (workstations, PCs and supercomputers), getting them running and then keeping them running in spite of the activities of users who tend to cause the systems to fail.  System Administrator works for users use the system to produce work. should not just cater for one or two selfish needs, but also work for the benefit of a whole community, which is a global community of machines and organizations It is often difficult balancing act to determine the best policy, which accounts for the different needs of everyone with a stake in a system. Once a computer is connected to the Internet, we have to consider the consequences of being directly connected to all the other computers in the world. System administrators need to know a bit of everything Network Administration and System Administration The terms network administration and system administration exist separately and are used both variously and inconsistently by industry and by academics. Network System Administration Administration Network System administration administration is means the the term used management of traditionally by network mainframe and infrastructure Unix engineers to devicesadministration Network and system (routers aredescribe the challenging as the increasingly complexity of computer systems is and switches), theincreases all the time. of management management of computers whether PCs in a network they are coupled  Scope of Network Design and Management The management of a network consists of procedures and services that keep the network running properly. An important part of network management entails making sure that the network is available (or up and running as IT professionals) when employees and managers need it. Other admin activities are: 1. Monitoring the network capacity to ensure that all transmission requirements can be met. 2. Adding capacity to the network by increasing band width interconnecting additional modes, or creating and interconnecting additional networks. 3. Training people to use the network effectively 4. Assisting IT professionals in organizational applications that will make good use of the network’s capabilities. 5. Backing up the network software and data regularly to protect against the failure of network or any of its components 6. Putting security procedures in place to make certain that only authorized users have access to the network and ensuring that all security procedures are followed 7. Making sure the network personnel can respond quickly and effectively in the event of a network operational or security failure. 8. Diagnosing and troubleshooting problems on the network and determining the best course of action to take to solve them. Goal of Network Design and Management o To keep the network running properly, configuring and managing services that are provided over the network. There are many services that we use regularly, some work in the background enabling other services to run smoothly.  Challenges of Network Design and Management System administration is not just about installing operating systems. It is also includes planning and designing an efficient community of computers so that real users will be able to get their jobs done. That means: Designing a network which is logical and efficient. Deploying large numbers of machines which can be easily upgraded later. Deciding what services are needed. Planning and implementing adequate security. Providing a comfortable environment for users. Developing ways of fixing errors and problems which occur. Keeping track of and understanding how to use the enormous amount of knowledge which increases every year. Principles of Network Design and Management Policy (the foundation) o System administration begins with a policy – a decision about what is wanted and what should be, in relation to what can be afforded. o Policy speaks of what we wish to accomplish with the system, and what we are willing to tolerate of behaviour within it. o It must refer to both the component parts and to the environment with which the system interacts. o If we cannot secure predictability, then we cannot expect long-term conformance with a policy.  Principles of Network Design and Management Predictability o The highest level aim in system administration is to work towards a predictable system, Predictability has limits. It is the basis of reliability, hence trust and therefore security. o Policy and predictability are intertwined. o System administration is difficult because it involves a kind of ‘search’ problem. o The search for a stable aspect in the general policies that can lead to stable and predictable behaviour. o In choosing policy, one might easily promote a regime of cascading failure, of increasing unpredictability that degenerates into disorder. o Avoiding these regimes is what makes system administration difficult. Principles of Network Design and Management Scalability o Scalable systems are those that grow in accordance with policy; i.e. they continue to function predictably, even as they increase in size. o The important point to understand about predictability is that it has limits. o Human–computer systems are too complex and have too many interactions and dependencies to be deterministic. o When we speak of predictability, it must always be within a margin of error. o If this were not the case, system administration would not be difficult.  Network Design Designing a network can be a challenging task as it involves more than just connecting computers. A network requires many features for it to be reliable, manageable and scalable network. Principles of Network Design Good designs should: o Deliver services requested by users o Deliver acceptable throughput and response times o Be within budget and maximize cost efficiencies o Be reliable o Be expandable without major redesign o Be manageable by maintenance and support staff o Be well documented o Network criteria Networks: key issues Performance Throughput Delay Reliability Data transmitted are identical to data received. Measured by the frequency of failure The time it takes a link to recover from a failure Security Protecting data from unauthorized access Network Structure/Network Design Model/ Topology  Physical Topology Refers to the physical lay out of a network Two or more devices connected to a link, two or more links form a topology. Topology is the schematic description of a network arrangement, connecting various nodes (sender and receiver) through lines of connection 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 MESH Topology It is a point-to-point connection to other nodes or devices. Traffic is carried only between two devices or nodes to which it is connected. Types of Mesh Topology Partial Mesh Topology : In this topology some of the systems are connected in the same fashion as mesh topology but some devices are only connected to two or three devices. Full Mesh Topology : Each and every nodes or devices are connected to each other.  MESH Features Topology Fully connected. Robust. Not flexible. Advantages Each connection can carry its own data load. It is robust. Fault is diagnosed easily. Provides security and privacy. Disadvantages Installation and configuration is difficult. Cabling cost is more. Bulk wiring is required. STAR Topology In this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node.  STAR Features Topology Every node has its own dedicated connection to the hub. Acts as a repeater for data flow. Can be used with twisted pair, Optical Fibre or coaxial cable. Advantages Fast performance with few nodes and low network traffic. Hub can be upgraded easily. Easy to troubleshoot. Easy to setup and modify. Only that node is affected which has failed rest of the nodes can work smoothly. Disadvantages Cost of installation is high. Expensive to use. If the hub is affected then the whole network is stopped because all the nodes depend on the hub. Performance is based on the hub, that is it depends on its capacity BUS Topology Bus topology is a type of network connection in which every computer and network device is connected to single cable.  BUS Topology Features of Bus Topology It transmits data only in one direction. Every device is connected to a single cable Advantages of Bus Topology 1. It is cost effective. 2. Cable required is least compared to other network topology. 3. Used in small networks. 4. It is easy to understand. 5. Easy to expand joining two cables together. Disadvantages of Bus Topology Cables fails then whole network fails. If network traffic is heavy or nodes are more the performance of the network decreases. Cable has a limited length. It is slower than the ring topology RING Topology It forms a ring as each computer is connected to another computer, with the last one connected to the first. Each device has a dedicated point to point connection with only the two devices on either side of it Exactly two neighbours for each device. When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along  RING Topology Features A number of repeaters are used and the transmission is unidirectional. Data is transferred in a sequential manner that is bit by bit. Advantages 1. Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data. 2. Cheap to install and expand Disadvantages 3. Troubleshooting is difficult in ring topology. 4. Adding or deleting the computers disturbs the network activity. 5. Failure of one computer disturbs the whole network. It is a types of topology which is a mixture of two or more topologies. HYBRID Topology For example, if in an office, one department ring topology is used and in another star topology is used, connecting these topologies will result in Hybrid Topology (ring topology and star topology).  Features HYBRID Topology It is a combination of two or topologies Inherits the advantages and disadvantages of the topologies included Advantages Reliable as Error detecting and troubleshooting is easy. Effective. Scalable as size can be increased easily. Flexible. Disadvantages Complex in design. Costly. Network Technology There are generally two primary categories of network technology: local area network (LAN) – covers an area less than 2 miles wide area network (WAN) - can be worldwide Network of a size in between are normally referred to as metropolitan area network (MAN) - span tens of miles.