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Connecting to a computer Network. Network interface Card (NIC) Connecting Devices Network Cables Wireless Networks Network Topology Network Operating System. Network Interface Card (NIC). Transferring message from computer to network cables
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Connecting to a computer Network • Network interface Card (NIC) • Connecting Devices • Network Cables • Wireless Networks • Network Topology • Network Operating System
Network Interface Card (NIC) • Transferring message from computer to network cables • Is an expansion card (or built-in) to motherboard • is the KEY hardware component for connecting the computer to a network • of course need software setting too …
Each NIC has a unique hardware number • MAC Address (Medium Access Control) • used to identify the computer in a network • e.g. 00-10-B5-59-CF-56 • already burnt in by manufacturer
Network Card Classification • by type of connectors • AUI / BNC / RJ-45 • by Expansion bus • ISA / PCI / PCMCIA / USB • by Bandwidth • 10Mbps / 100Mbps / 1000Mbps • 10/100 Mbps (Combo)
Connecting Device • For connecting the computers and devices in a network • repeater • hub • bridge • switch • router
Repeater • one-port to one-port • a device that • amplifies the signal it receives and then resend it • because there has signal attenuation during the transmission of signal over long distance • remove unwanted noise • do not consider to forward the signal or not
Hub • a repeater with multi-ports (multi-ports repeater) • also do not consider to forward the signal or not • disadvantage : • shares bandwidth • broadcast the signal to all other ports • for heavy traffic network, the performance degrade
Bridge • one-port to one-port • used to interconnect LAN segment • with the advantage of repeater plus • when receiving a signal, will consider to forward the signal or not Yes / No ?
Switch • a bridge with multi-ports (multi-ports bridge) • unlike hub, it does not broadcast signal to all ports • but just send the signal to destination port • because it contains a switching tables
D C E B F A To E
Router • a device used to connect multiple networks • an essential device for connecting a LAN to the internet • To translate information between LAN and the Internet • LAN - private IP address • Internal - real IP address
WAN LAN • A router also has the function of choosing the best route (path) for information flow • best path = shortest distance, shortest time • depending on the protocol used
Network cables • Used to connect computers and other devices • Common types : • twister pair cable • coaxial cable • optical fibre
Twisted-Pair Cable • like telephone cables • has a square, plastic head • RJ-45 connector • telephone … RJ-11 connector • often used in LAN • Type of twisted-pair cable • shielded twisted pair (STP) • unshielded twisted pair (UTP) …. Most common
Shielded Twisted Pair cable (STP) • has a metal wrapper around each wire • to reduce noise due to electromagnetic (EM) wave • i.e. to reduce interference • Unshielded Twisted Pair cable (UTP) • do not has a metal wrapper around each wire • Types of UTP : • Category 1, 2, 3, 4, 5 • Most common : Cat. 5 • data transfer rate up to about 100Mbps
Coaxial Cable • commonly used for VCR and cable TV connections • uses BNC connector • Adv : • retain the strength of signal over long distance transmission (c.f. twisted pair cable)
Structure of a coaxial cable • Innermost = copper wire • then ===== a sheath of insulation • then ===== a metal wire mesh • conducts and shields against interference • Outermost = coating (plastic) • More insulation of coaxial cable • allow coaxial cable to carry more information than twisted pair cable
Crosstalk • because twisted pair and coaxial cable use copper conductors • transmit electrical signals • generate EMI • electromagnetic interference • EMI disturb the quality of transmission • = CROSSTALK
Optical fibre cable • made of a bundle of glass threads that transmit light beams • using the principles of total internal reflection • Adv (c.f. twisted pair and coaxial) • greater signal carrying capacity • faster data transmission • less susceptibility to noise / interference • from other device
Adv (cont’d) • Better Security for signal during transmission • much thinner • less heavy • Disadv : • more expensive • more technique is require during the installation • more easy to break