"Networking 101: Basics" Jim Gogan INLS184

Introduction - Why network? l Communicate with others close by l Communicate with others far away l Gain access to information not on your computer l Share resources (software, peripherals)

*ANS? l LANs l WANs l MANs l internets l Internet l Intranet

Components of a LAN l Cable l Workstations/Servers l Interface cards (NICs) l Hubs/switches/etc. l Peripherals l Network protocols

Cable l Types of Cables –Coaxial cable –Twisted pair –Fiber optics l Wireless

Cabling Topologies l Daisy Chain l Bus l Ring l Star

Daisy Chain l Simplest to do l One device hooked to device after it l If broken, all connections are lost l Daisy Chain network example: original LocalTalk

Bus l Packets move along a straight line l Works like a trolley, must have bumpers at ends of lines l Devices are connected through taps on the line l As long as taps aren’t disconnected, network stays up l Bus network example: Thin-net Ethernet

Ring l Cable must form complete, unbroken ring l Packets with presence of token (usually) l If ring broken, all devices may go down l Ring network example: Token Ring

Star l Devices are connected along “arms” of the star l Arms connected to central hub l When disconnected, only that arm of the star is affected l Star network example: 10BaseT Ethernet

Workstations l The computer on an individual’s desk l May have its own local devices/peripherals as well as access to networked peripherals

Servers l Workstation (often higher end) with specific functions l Usually provides services: –File services –Web services – services

Interface cards l Connect individual devices to network l Must match type of device and type of cable

Hubs and Switches and Network Devices l Depends on type of network installed l More about these later …...

Peripherals l Accessory devices (printers, fax machines, backup devices, etc.) l Originally connected thru workstations or servers, now directly network connected l Originally dumb, now intelligent enough to do some real damage

Protocols l Common language among computers l Analogous to addressing envelopes l Many different protocols out there l Different “layers” use different protocols

Network Addressing l Must be unique to each device l A single physical device can have several network addresses l Usually divided into two parts: network and node (both parts can be combined into one address) l May be permanent (static) or temporary (dynamic)

Packets l Way information moves across the wire l Packets can carry data or protocol/control information only l Difference between “packet” and “cell”

How Networks Grow l File sharing l Application sharing l Peripheral sharing l Client/server applications – –WWW l Multimedia applications

Dividing/Expanding Networks l Why: –Too much traffic –Too many nodes –Distance limitations l How: –Repeaters –Bridges –Routers

Performance Terms l Bandwidth l Throughput l Latency (delay) l Jitter l Loss

Other Aspects/Considerations l Security l Management

Key Points l Standards= Good! l Simplicity= Good! (easy to develop) l Ethernet= Good! (it’s simple) l TCP/IP= Good! (it’s simple)