2Computer NetworksPrimary purposes of network is to increase productivity.The minimum requirements for setting up a network are:An NIC cardNetwork MediaConnectors
3Network Interface Circuit (NIC) Card IS a printed circuit board that provides network communication capabilities to and from a PC.Amplifies electronic signalsPackage data for transmissionPhysically connects computer to transmission mediaEach NIC card is stored with a unique address provided by IEEE called MAC address.MAC is a 48 bit address, the first 24 bits is the vendor code and the next 24 bits represent the Serial Number.
4Network MediaIS the actual physical environment which data travels as it moves from one computer to another, and it connects network devices.The most common types of network media are:Coaxial CablesTwisted Pair CablesFiber Optic CablesWireless
5Coaxial Cables Consists of Used to connect dish antenna to a TV set. Single copper conductorPlastic insulationOver a wire mesh( Braided Copper Shielding)Another plastic insulation.Used to connect dish antenna to a TV set.Coaxial Cables are of two types:Thicknet (longest distance )ThinnetConnectors used:BNCTTerminators.
6Twisted Pair Cables Used for both LANs and telephone systems. Composed of four color-coded pairs of copper conductors twisted around each other.The outer jacket provides protection and keeps the pairs in alignment.There are two types:Unshielded Twisted Pair Cable (UTP)Shielded Twisted Pair Cable (STP)
7Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Used in normal office environments.IS the most popular network media.Connectors used is RJ 45 connectors.
8Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) The advantage of UTP is its ability to limit signal degradation from electromagnetic interference (EMI) and Radio frequency interference.Reduces CrosstalkThere are different categories of UTP cable.The most used is CAT5 –have the maximum segment length 100m.(shorter than coax)
9Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Implementation Straight through CableUsed forSwitch to routerSwitch to PC or serverHub to PC or server
10Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Implementation Crossover Cable (pins 1 and 2 on one connector connect to pins 3 and 6 on the other)Used forSwitch to switchSwitch to hubHub to hubRouter to router PC to PC
11Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Implementation Roll-over Cable (pins 1 on one connector connect to pins 8 on the other)Used forConsole port of a router or switch to the PC
12Twisted Pair Cables shielded Twisted Pair Cable (STP) Protect against signal degradation.Each pair of wires is wrapped in a metallic foil.The four pairs of wires are then wrapped in an overall metallic braid or foil.
13Twisted Pair Cables shielded Twisted Pair Cable (STP) Reduces electrical noise within and outside the cable.Used in Token Ring.Maximum segment length is 100m
14Fiber Optic Cables Capable of conducting modulated light transmission. Consists of two fibers encased in separate sheaths.A cable, consisting of a center glass core surrounded by layers of plastic, that transmits data using light rather than electricity.Connectors used are multimode.Not effected by EMIThere are two types of fiber-optic cables:Single-modeMultimode
15Fiber Optic Cables Single-mode Allow only one mode of light to propagate through the fiber.Capable of higher bandwidth and greater distancesUses Lasers as the light-generation method and is expensive.
16Fiber Optic Cables Multimode Allows multiple modes of light to propagate through the fiber.Often used for workgroup applications.The segment length is less than the single-mode.
17WirelessThe device use to signal distribution called wireless hub or access pointTo receive the signal from the access point the pc needs to install wireless (NIC)Radio frequency (RF)Transmit voice, video and dataAffected by electromagnetic interferenceLimited distanceWireless LAN (WLAN) use radio waves, microwave and Infrared waves.
19Network Topologies The configurations of network components Widely used network topologiesBusStarExtended starRingMeshPartial Mesh
20Bus Network Topology Most simple network topology All devices connected to a common central cable (wire or other media )InexpensiveEasily expandedIf cable fails, the entire network will shut downEarlier Ethernet commonly implement a bus topology
22Star Network TopologyStar topology is centered around central routing device called a switch or a hub by point-to-point links.All network nodes connect to the hubEasy to install and updateIf hub fails, network failsDisadvantage that it require more cabling therefore, higher cost than the bus.Extended star
24Ring Network Topology Each node connected to two other nodes in a ring Similar to the buss, but with the ends of the buss connected together by unidirectional transmission link to form a single closed loop.Each station on the network connects to the network at a repeater.Expensive and difficult to installOne example of a ring topology is Token Ring networks
26Dual-Ring Tow rings allow data to be sent in both directions Creates redundancy.
27Mesh Network Topology Every node connected to every other node Fast ReliableNo hub or bus to failIf one device goes down, it is the only node affectedExpensiveEvery node must be wired to every other nodeDifficult to add nodesIf there are 32 nodes in a mesh network and you wish to add a new node, how many new cables must you add?32 nodesAdd new 33rd nodeNew node must connect to all 32 existing nodes, therefore 32 cables to add
28Partial MeshAt least one derive is connected to all other devices without being fully meshed.