HBT 2204 Network Design And Management PDF

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HBT 2204- Networks Design and management Notes A computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications and allow sharing of resources and information among interconnected devices. Computer network design refers to the planning of the implementation of a computer network infrastructure. Network design is generally performed by network designers, engineers, IT administrators and other related staff. It is done before the implementation of a network infrastructure. The objective of network design is to satisfy data communication requirements while minimizing expense. Requirement scope can vary widely from one network design project to another based on geographic particularities and the nature of the data requiring transport. There are a number of details your network infrastructure design should show, these include:     

A clear map of the network. The structure and layout of the cabling required. The quantity, type and location of all devices on the network. Your IP addressing structure. Details of your network security architecture and processes.

Five Things to Be Considered in Designing a Network. Important things to consider include balancing security issues with the desire for easy access to information; building redundancy into the network in anticipation of breakdowns; and standardizing hardware and software to keep maintenance costs in check. Connectivity and Security Network connectivity today means more than Ethernet cables and wireless access points. People today are more connected while mobile than ever before and many of them want access to company email and data while they are out of the office. Balancing those needs while maintaining security is a challenge that needs to be addressed in the design phase of any network. This includes where data is stored, either in-house or offsite with cloud-based solutions, what types of information should be accessible, who should be able to access it, and which types of devices should be included. Firewalls and access servers need to be secure without slowing down operations.

Redundancy and Backing Up Redundancy means having backup devices in place for any mission-critical components in the network. Even small organizations should consider using two servers. Two identical servers, for example, can be configured with fail-safes so that one will take over if the other fails or requires maintenance. A good rule of thumb is to have redundant components and services in place for any part of a network that cannot be down for more than an hour. If an organization hosts it own Web servers, or cannot be without Internet connectivity, a second connection should be in place. Having an extra switch, wireless router, and a spare laptop onsite is a good practice for ensuring that downtime is kept to a minimum. Standardization of Hardware and Software Standardization of the hardware and software used in a network is important for ensuring the network runs smoothly. It also reduces costs associated with maintenance, updates and repairs. Conducting a full audit of the current computer systems, software and peripherals will help to determine which should be standardized. A CEO or director may require special consideration, but if 90 percent of the employees use the same notebooks, with the same word processing and email programs, a software or hardware patch across the organization can be conducted much less expensively than if everyone used a different computer model with different software installed on each. Disaster Recovery Plan A detailed disaster recovery plan should be a part of any network design. This includes, but is not limited to, provisions for back-up power and what procedures should be followed if the network or server crashes. It should also include when data is backed up, how it is backed up and where copies of the data are stored. A comprehensive disaster recovery plan includes office disasters, building disasters, and metropolitanwide disasters. In most cases, important data should be backed up daily. Many organizations do a full weekly backup, with daily incremental backups that copy any files that have been modified since the last weekly backup. Backup files should be stored in a secure location off-site in the event of a building disaster, such as a fire. Future Growth of the Organization While it is not always possible to anticipate how large an organization may be five years in the future, some allowances for future growth must be built into the network design. For example, Microsoft Small Business Server can be an excellent choice for many small organizations. However, if your office already has sixty employees, Small Business Server could soon be a wasted investment, as it has a limit of only 75 users.

Network design should factor in at least 20 percent growth per year, including everything from switch ports to data backup systems.

Analysis and Design Principles. There are two common approaches to analyze and design networks: The top-down approach: The top-down design approach simplifies the design process by splitting the design tasks to make it more focused on the design scope and performed in a more controlled manner, which can ultimately help network designers to view network design solutions from a business-driven approach. The bottom-up approach: In contrast, the bottom-up approach focuses on selecting network technologies and design models first. This can impose a high potential for design failures, because the network will not meet the business or applications’ requirements. Network management and administration refers to the processes, tools and applications used to administer, operate and maintain a network infrastructure. Performance management and fault analysis are also included in network management. The International Organization for Standardization (ISO) network management model defines five functional areas of network management. 

Fault Management—Detect, isolate, notify, and correct faults encountered in the network.

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Performance Management—Monitor and measure various aspects of performance so that overall performance can be maintained at an acceptable level.

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Security Management—Provide access to network devices and corporate resources to authorized individuals.

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Accounting Management—Usage information of network resources.

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Configuration Management—Configuration aspects of network devices such as configuration file management, inventory management, and software management.

Computer networking or Data communications (Datacom) is the engineering discipline concerned with the computer networks. Computer networking is sometimes considered a sub-discipline of electrical engineering, telecommunications, computer science, information technology and/or computer engineering since it relies heavily upon the theoretical and practical application of these scientific and engineering disciplines. Network Hardware At least two computers (Server or Client workstation). Networking Interface Card's (NIC) Network Adapters A network adapter, more commonly known as Network Interface Card (NIC), is an expansion board that makes it possible to connect a PC to a network. Network adapters are needed for Ethernet and Token Ring networks, but not for online services which use modems to make the connection. The adapters in a network are connected to each other by cable. Network adapters are available in different types such as desktop adapters, mobile adapters, server adapters, and handheld adapters. Hub  An unintelligent network device that sends one signal to all of the stations connected to it.  All computers/devices are competing for attention because it takes the data that comes into a port and sends it out to all the other ports in the hub.  Traditionally, hubs are used for star topology networks, but they are often used with other configurations to make it easy to add and remove computers without bringing down the network.  Resides on Layer 1 of the OSI model Switch  Split large networks into small segments, decreasing the number of users sharing the same network resources and bandwidth.  Understands when two devices want to talk to each other, and gives them a switched connection  Helps prevent data collisions and reduces network congestion, increasing network performance.  Most home users get very little, if any, advantage from switches, even when sharing a broadband connection.  Resides on Layer 2 of the OSI model. Bridge  Connects two LANs and forwards or filters data packets between them.  Creates an extended network in which any two workstations on the linked LANs can share data.  Transparent to protocols and to higher level devices like routers.

Forward data depending on the Hardware (MAC) address, not the Network address (IP).  Resides on Layer 2 of the OSI model. Repeater  Used to boost the signal between two cable segments or wireless access points.  Can not connect different network architecture.  Does not simply amplify the signal, it regenerates the packets and retimes them.  Resides on Layer 1 of the OSI model. Router  A device that connects any number of LANs.  Uses standardized protocols to move packets efficiently to their destination.  More sophisticated than bridges, connecting networks of different types (for example, star and token ring)  Forwards data depending on the Network address (IP), not the Hardware (MAC) address.  Routers are the only one of these four devices that will allow you to share a single IP address among multiple network clients.  Resides on Layer 3 of the OSI model. Additional Network Hardware Devices Network Interface Cards (NICs) 1. Puts the data into packets and transmits packet onto the network. 2. May be wired or wireless. Gateway 3. Connects networks with different protocols like TCP/IP network and IPX/SPX networks. 4. Routers and Gateways often refer to the same device. Proxy server 5. Isolates internal network computers from the internet. 6. The user first access the proxy server and the proxy server accesses the internet and retrieves the requested web page or document. The user then gets a copy of that page from the proxy server. A connection medium, usually a wire or cable, although wireless communication between networked computers and peripherals is also possible. Coaxial Cable, Twisted pair, Fiber-optic, Atmosphere/Wireless – Choose Media based on : •Wiring configurations •Distance and location limitations •Speed •Reliability •Security •Budget Dialup over telephone line. DSL (Digital Subscriber Line)  High-speed (256 Kbps – 55 Mbps), Full-duplex. 

Connectors  RJ-45 - Standard connectors used for unshielded twisted-pair cable.   Network Softwares. Operating Systems: In order to transmit signals across a network, it is necessary for the computer to communicate with its modem or Network Interface Card. Network Operating Systems (NOS) provide the protocols necessary to achieve this goal, but each different type of modem or NIC needs to be able to communicate with the particular NOS. It is therefore necessary to install the special software that comes with the interface device. This software is often referred to as a driver. Computers made today usually come with both the interface and necessary drivers installed. Occasionally, you must install the modem or NIC yourself. It is necessary to install the correct driver for that interface device. Failure to so install the driver means that the device will be unable to communicate over the network or with the computer it is installed in. Network Operating Systems not only allow communication across a network, they also allow a network administrator to organize resources, control access, and ensure that the network is operating efficiently. •Operating System – Unix, Windows, Linux, OSx, Solairs –System Software •Application Software – Used to perform specific tasks Purpose Computer networks can be used for a variety of purposes: Facilitating communications. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing. Sharing hardware. In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer Sharing files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks. Sharing software. Users connected to a network may run application programs on remote computers. Network Topology.

The topology defines how network devices (computers, printers..etc) are connected and how the data flows from one device to another. There are two conventions while representing the topologies. The physical topology defines how the devices are physically wired. The logical topology defines how the data flows from one device to another. Network Topology. The topology defines how the devices (computers, printers etc) are connected and how the data flows from one device to another. There are two conventions while representing the topologies. The physical topology defines how the devices are physically wired. The logical topology defines how the data flows from one device to another. Broadly categorized into, Bus topology: Bus Topology is the simplest of network topologies. In this type of topology, all the nodes (computers as well as servers) are connected to the single cable (called bus), by the help of interface connectors. This central cable is the backbone of the network and is known as Bus (thus the name). Every workstation communicates with the other device through this Bus. A signal from the source is broadcasted and it travels to all workstations connected to bus cable. Although the message is broadcasted but only the intended recipient, whose MAC address or IP address matches, accepts it. If the MAC /IP address of machine doesn’t match with the intended address, machine discards the signal. A terminator is added at the ends of the central cable, to prevent bouncing of signals. A barrel connector can be used to extend it. Below I have given a basic diagram of a bus topology and then have discussed advantages and disadvantages of Bus Network Topology Advantages (benefits) Bus Topology 1) It is easy to set-up and extend bus network. 2) Cable length required for this topology is the least compared to other networks. 3) Bus topology costs very less. 4) Linear Bus network is mostly used in small networks. Good for LAN. Disadvantages (Drawbacks) of Bus Topology

1) There is a limit on central cable length and number of nodes that can be connected. 2) Dependency on central cable in this topology has its disadvantages. If the main

cable (i.e. bus ) encounters some problem, whole network breaks down. 3) Proper termination is required to dump signals. Use of terminators is a must. 4) It is difficult to detect and troubleshoot fault at individual station. 5) Maintenance costs can go higher with time. 6) Efficiency of Bus network reduces as the number of devices connected to it increases. 7) It is not suitable for networks with heavy traffic. 8) Security is very low because all the computers receive the sent signal from the source. Ring Topology Ring topology was in the beginning of LAN area. In a ring topology, each system is connected to the next system.

Each device has a transceiver which behaves like a repeater which moves the signal around the ring; ideal for token passing access methods. In this topology signal degeneration is low; only the device that holds the token can transmit which reduces collisions. Advantages of Ring Topology 1) This type of network topology is very organized. Each node gets to send the data when it receives an empty token. This helps to reduces chances of collision. Also in ring topology all the traffic flows in only one direction at very high speed. 2) Even when the load on the network increases, its performance is better than that of Bus topology. 3) There is 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 of Ring Topology

1) Each packet of data must pass through all the computers between source and destination. This makes it 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. 4) Network cards are expensive as compared to Ethernet cards and hubs.

Star topology In Star topology, all the components of network are connected to the central device called “hub” which may be a hub, a router or a switch. Unlike Bus topology (discussed earlier), where nodes were connected to central cable, here all the workstations are connected to central device with a point-to-point connection. So it can be said that every computer is indirectly connected to every other node by the help of “hub”. All the data on the star topology passes through the central device before reaching the intended destination. Hub acts as a junction to connect different nodes present in Star Network, and at the same time it manages and controls whole of the network. Depending on which central device is used, “hub” can act as repeater or signal booster. Central device can also communicate with other hubs of different network. Unshielded Twisted Pair (UTP) Ethernet cable is used to connect workstations to central node. Advantages of Star Topology 1) As compared to Bus topology it gives far much better performance, signals don’t necessarily get transmitted to all the workstations. A sent signal reaches the intended destination after passing through no more than 3-4 devices and 2-3 links. Performance of the network is dependent on the capacity of central hub. 2) Easy to connect new nodes or devices. In star topology new nodes can be added easily without affecting rest of the network. Similarly components can also be removed easily. 3) Centralized management. It helps in monitoring the network. 4) Failure of one node or link doesn’t affect the rest of network. At the same time its easy to detect the failure and troubleshoot it. Disadvantages of Star Topology 1) Too much dependency on central device has its own drawbacks. If it 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. Mesh topology. A mesh physical topology is when every device on the network is connected to every device on the network; most commonly used in WAN configurations Helps find the quickest route on the network; provides redundancy. Very expensive and not easy to set up. Advantages of Mesh topology 1) Data can be transmitted from different devices simultaneously. This topology can withstand high traffic.

2) Even if one of the components fails there is always an alternative present. So data transfer doesn’t get affected. 3) Expansion and modification in topology can be done without disrupting other nodes. Disadvantages of Mesh topology

1) There are high chances of redundancy in many of the network connections. 2) Overall cost of this network is way too high as compared to other network topologies. 3) Set-up and maintenance of this topology is very difficult. Even administration of the network is tough. Hybrid topology Hybrid, as the name suggests, is mixture of two different things. Similarly in this type of topology we integrate two or more different topologies to form a resultant topology which has good points(as well as weaknesses) of all the constituent basic topologies rather than having characteristics of one specific topology. This combination o...