Local and Wide Area Networks: Local and Wide Area Networks: Understanding the PiecesUnderstanding the Pieces

John H. Porter John H. Porter University of Virginia Coastal Research CenterUniversity of Virginia Coastal Research Center

WHY have a LAN (Local Area WHY have a LAN (Local Area Network) hooked to the Internet?Network) hooked to the Internet?

Sharing of ResourcesSharing of Resources• disks disks • printersprinters

Access to InternetAccess to Internet• Electronic Mail Electronic Mail • WWW pagesWWW pages• use net resourcesuse net resources

Control of setups of multiple computersControl of setups of multiple computers

Ethernet - How does it work?Ethernet - How does it work?

Ethernet is the most common system Ethernet is the most common system used on LANsused on LANs

It operates the same way a group It operates the same way a group discussion worksdiscussion works• wait for a pausewait for a pause• start to talk - but stop if someone else talksstart to talk - but stop if someone else talks• in case of “collision” wait for a pause and in case of “collision” wait for a pause and

try againtry again

What are the PARTS you need?What are the PARTS you need?

Network Interface Network Interface Cards (NICs) for Cards (NICs) for computerscomputers

Category 5 (CAT5) Category 5 (CAT5) cables running to cables running to

Hubs or Switches Hubs or Switches Optical cable to Optical cable to

interconnect hubs interconnect hubs and switchesand switches

Server computers Server computers for printing & diskfor printing & disk

A router to connect A router to connect them to the Internetthem to the Internet

A high speed A high speed telecommunications telecommunications line to an Internet line to an Internet Service Provider Service Provider (ISP)(ISP)

Graphical NetworkGraphical Network

Server PCServer PC

PCPC

PCPC

PCPC

HubHub

HubHub

RouterRouterInternetInternetServiceServiceProviderProvider

CAT5 CableCAT5 Cable

Optical or CAT5 CableOptical or CAT5 Cable

ISDN,T1 etc.ISDN,T1 etc.

Network Interface CardsNetwork Interface Cards

Need one for each PC connected to the Need one for each PC connected to the networknetwork

Most modern MacIntosh computers Most modern MacIntosh computers have Ethernet capabilities built inhave Ethernet capabilities built in

Cost: $20-$100 Cost: $20-$100

CAT 5 CablesCAT 5 Cables

““twisted pair” copper wirestwisted pair” copper wires Have a RJ-45 connector at each endHave a RJ-45 connector at each end

• looks like an extra-wide modular phone looks like an extra-wide modular phone plugplug

Run between the computer and its “hub”Run between the computer and its “hub” Cost: about $250 per installed “drop” Cost: about $250 per installed “drop”

• 2 wall jacks2 wall jacks

Hubs and SwitchesHubs and Switches

Hubs connect PCs together to form a Hubs connect PCs together to form a networknetwork• in a minimal LAN, this might be all you needin a minimal LAN, this might be all you need

Switches are like Hubs but are “smart” Switches are like Hubs but are “smart” enough to optimize network traffic that enough to optimize network traffic that passes through thempasses through them

Cost: $50-$200 for most Hubs, $1,000-Cost: $50-$200 for most Hubs, $1,000-$3,000 for most switches$3,000 for most switches

– Cost depends on number of portsCost depends on number of ports

Optical or CAT5 CablingOptical or CAT5 Cabling

Hubs, switches and routers can be Hubs, switches and routers can be connected using optical cables or CAT5 connected using optical cables or CAT5 wiringwiring

Optical cables are preferred for Optical cables are preferred for connecting buildings due to reduced connecting buildings due to reduced susceptibility to lightning etc.susceptibility to lightning etc.

Server(s)Server(s)

A server is a “normal” PC usually A server is a “normal” PC usually running Windows NT or Linux that running Windows NT or Linux that shares disks and printers connected to shares disks and printers connected to it with other computers on the net.it with other computers on the net.

It can be configured to provide security It can be configured to provide security so that users only have access to “their” so that users only have access to “their” part of the systempart of the system

Cost: $3,000-$10,000Cost: $3,000-$10,000

RouterRouter

A router is a “very smart” network A router is a “very smart” network switch. It calculates the most efficient switch. It calculates the most efficient route for network packets to take. route for network packets to take.

Cost: $1,000-6,000Cost: $1,000-6,000

Internet ConnectionInternet Connection

A Internet connection to an Internet A Internet connection to an Internet Service Provider (ISP) can take many Service Provider (ISP) can take many forms:forms:• modem (56KB/S max) ($20/month)modem (56KB/S max) ($20/month)• ISDN (64KB/S or 128KB/S) ($200/month)ISDN (64KB/S or 128KB/S) ($200/month)• Leased lineLeased line

– T1 (1.5 MB/sec) ($1,000/month)T1 (1.5 MB/sec) ($1,000/month)– DSLDSL

Cutting Costs: The Ultimate Cutting Costs: The Ultimate Mini-NetMini-Net

Server PCServer PC

PCPC

PCPC

PCPC

HubHub

56K 56K modemmodem

InternetInternetServiceServiceProviderProvider

CAT5 CableCAT5 Cable

Serial CableSerial Cable

Regular phone lineRegular phone line

Server runs either WinNT orServer runs either WinNT orWin98 with Wingate 3.1 software Win98 with Wingate 3.1 software (http://www.wingate.com)(http://www.wingate.com)

Cost: NICs $60+Hub $50+Cables $40+Software $40= Cost: NICs $60+Hub $50+Cables $40+Software $40= $190$190Recurrent cost: $20/month for ISP feesRecurrent cost: $20/month for ISP fees