Local and Wide Area Networks: Understanding the Pieces John H. Porter University of Virginia Coastal Research Center
WHY have a LAN (Local Area Network) hooked to the Internet? • Sharing of Resources • disks • printers • Access to Internet • Electronic Mail • WWW pages • use net resources • Control of setups of multiple computers
Ethernet - How does it work? • Ethernet is the most common system used on LANs • It operates the same way a group discussion works • wait for a pause • start to talk - but stop if someone else talks • in case of “collision” wait for a pause and try again
Network Interface Cards (NICs) for computers Category 5 (CAT5) cables running to Hubs or Switches Optical cable to interconnect hubs and switches Server computers for printing & disk A router to connect them to the Internet A high speed telecommunications line to an Internet Service Provider (ISP) What are the PARTS you need?
Server PC PC PC PC Graphical Network Hub Internet Service Provider Router Hub CAT5 Cable Optical or CAT5 Cable ISDN,T1 etc.
Network Interface Cards • Need one for each PC connected to the network • Most modern MacIntosh computers have Ethernet capabilities built in • Cost: $20-$100
CAT 5 Cables • “twisted pair” copper wires • Have a RJ-45 connector at each end • looks like an extra-wide modular phone plug • Run between the computer and its “hub” • Cost: about $250 per installed “drop” • 2 wall jacks
Hubs and Switches • Hubs connect PCs together to form a network • in a minimal LAN, this might be all you need • Switches are like Hubs but are “smart” enough to optimize network traffic that passes through them • Cost: $50-$200 for most Hubs, $1,000-$3,000 for most switches • Cost depends on number of ports
Optical or CAT5 Cabling • Hubs, switches and routers can be connected using optical cables or CAT5 wiring • Optical cables are preferred for connecting buildings due to reduced susceptibility to lightning etc.
Server(s) • A server is a “normal” PC usually running Windows NT or Linux that shares disks and printers connected to it with other computers on the net. • It can be configured to provide security so that users only have access to “their” part of the system • Cost: $3,000-$10,000
Router • A router is a “very smart” network switch. It calculates the most efficient route for network packets to take. • Cost: $1,000-6,000
Internet Connection • A Internet connection to an Internet Service Provider (ISP) can take many forms: • modem (56KB/S max) ($20/month) • ISDN (64KB/S or 128KB/S) ($200/month) • Leased line • T1 (1.5 MB/sec) ($1,000/month) • DSL
Server PC PC PC PC Cutting Costs: The Ultimate Mini-Net Server runs either WinNT or Win98 with Wingate 3.1 software (http://www.wingate.com) Internet Service Provider 56K modem CAT5 Cable Hub Serial Cable Regular phone line Cost: NICs $60+Hub $50+Cables $40+Software $40= $190 Recurrent cost: $20/month for ISP fees