Designing Local Area Network Network Scale/Networking Technologies/Physical Cables

Network Scale•Do you need:

– Large or Complex Network? – No server, One server, or many

servers?– Special networking equipments, such

as bridges, routers, and backbones?– Do the users of your network require

high bandwidth and therefore a fast (and expensive) network?

Network Scale• You need answer of these questions:

– How many client computers do you have?

– How far apart are the computers?– What software are you using?– What software will you use?– What special requirements do you

have?– How much you can spend?

How Many Client Computers?Peer Network (2 – 10 Users)Peer networks are good for:

– File Sharing– Printer Sharing– E-Mail– Tight budgets– Easy installation

They are not good for:

– Security– Backup– Organization of data– Database

applications– Large networks– Simple

administration– Internet/WAN access

Peer network (2 – 10 Users)This network requires Operating system such as Windows for workgroups, Windows 95, Macintosh, OS/2 and Novell DOS

Single-Server Netwrok(10 – 50 Users)Single-Server networks are good for:

– Centralized File Services– Network Printing– E-Mail– Workflow and groupware– Easy installation– Login security– Archiving– Organizing data– Simple administration– Internet/WAN access

They are not good for:

– Application serving– Distributed

organizations– Large organization

Single-Server Network (10 – 50 Users)This network requires network operating systems such as Windows NT, Netware, or OS/2 Server

Multiserver Networks(50 – 250 Users)Multiserver networks are good for:

– Centralized File Services

– Network Printing– E-Mail– Workflow and

groupware– Login security– Application services– Large databases– Internet/WAN access

They are not good for:

– Tight budgets– Easy installation– Organizing data– Simple

administration

Multiserver Networks (50 – 250 Users)This network requires network operating systems such as Windows NT, Netware, or OS/2 Server

Multiserver High-Speed Backbone Network (250 – 1000 Users)High speed backbone networks are good for:

– Centralized File Services

– Network Printing– E-Mail– Workflow and

groupware– Login security– Application services– Client-server

database– Internet/WAN access

They are not good for:

– Tight budgets– Easy installation– Organizing data– Speed

Enterprise Network (1000 + Users)Enterprise networks are good for:

– Network Printing– E-Mail– Workflow and

groupware– Login security– Application

services– Client-server

database– Internet access

They are not good for:

– Tight budgets– Easy installation– Centralized file

services– Organizing data– Speed

Enterprise network

FDDI ring FDDI ring

Engineering

Operation

Development

Research

Finance

Marketing

Sales

Administration

F & A Building R & D Building

Network Scale• How Far Apart Are the Computers?• What Software Are You Using?

– Word Processing and Spreadsheet– Graphics and CAD– Database Software

• What Software will You Use?– E-Mail– Internet Service– Groupware– Video Teleconferencing

Network Scale• What Special Requirements Do

You Have?– Do you have some special need of

security on your network? Are any of your computers more than 100 meters from where you will locate your Hub? Have there been any problems with electrical interferences? Etc.

• How Much Can You Spend?

Networking Technologies• Ethernet

– There is no guarantee that a computer will ever be able to transmit data in a heavily loaded network

– A computer only has to wait for silence before transmitting.

– Keeps about 30 clients per network segment • Fast Ethernet

– Fast Ethernet is more expensive than Ethernet and 10 times faster than Ethernet.

Networking Technologies• Token Ring

– All computers will eventually get to transmit data, no matter how loaded the network is.

– All computers will suffer some delay before being able to transmit white they wait for the token.

– Token Ring is a contemporary of Ethernet, but because the electronics required to control the network process are inherently more costly, it never caught on as well as Ethernet.

Networking Technologies• FDDI (Fiber Distribution Data

Interface)– FDDI is a token-passing ring network

that operates at 100 Mbps over two-counter-rotating fiber optic cable rings.

– FDDI is a fast fiber version of Token Ring and has been the choice for high speed backbones.

– FDDI rings can be quite large, up to about 13 Kilometers between devices with single mode fiber.

Networking Technologies• Fiber Channel

– Fiber Channel is a large high-speed backbone network technology that connects all the terminals, microcomputers, mainframes, local area networks, and other communications equipment.

– It currently operates at very high speeds and will eventually make a good choice for backbone connectivity in very large networks.

Networking Technologies• ATM

– Asynchronous Transfer Mode (ATM) (a.k.a. cell relay) is a technology originally designed for use in wide area networks that is now often used in backbone networks.

– ATM backbone switches typically provide point-to-point full duplex circuits at 155 Mbps (total of 310 Mbps).

– ATM uses a very different type of protocol than traditional LANs. It has a small 53-byte fixed length packet and is connection-oriented. Ethernet and token ring use larger variable length packets and are typically connectionless.

Physical Cables• Twisted Pair (UTP, STP)

– COST PER LOCATION: Cat 5 UTP Moderate Cat 5 STP Expensive

– DISTANCE LIMITATION: Cat 5 100 meters No more than 80 meters should be permanently installed between wall outlet and the patch panel in the computer room.

– OTHER LIMITATIONS: Cat 5 UTP is susceptible to interference from sources that generate EMI such as Motors HVAC unit, fluorescent lights etc.

– BANDWIDTH: Cat 5 100Mbps

Physical Cables• Coax

– COST PER LOCATION: Thinnet coaxial cable-lowest cost, Thicknet coaxial cable cost is double than Thinnet.

– DISTANCE LIMITATION: Thinnet – 185 meters, Thicknet - 500 meters per segment.

– OTHER LIMITATIONS: Because they are bus networks, the path of the installed cable must match the locations of the existing computers.

– BANDWIDTH: The useful bandwidth of coaxial cabling is 10Mbps.

Physical Cables• Fiber

– Although many types of optical fibers are available, but most network devices using only two types multi-mode with a core diameter 62.5 micron and single-mode with a core diameter 8.3 micron.

– COST PER LOCATION: Very Expensive.– DISTANCE LIMITATION: Multi-mode fiber – 2000

meters when using 10BaseFL and 400 meters when using Fast Ethernet 100BaseF. Modern cable bandwidth 622Mbps at 1000 meters. That bandwidth can be doubled each time the cable distance is halved.

– OTHER LIMITATIONS: Since fiber is immune to EMI, and because it is nearly impossible to tap. It should be handled with care during installation.

– BANDWIDTH: The useful bandwidth of optical fiber depends on the network standard. Single-mode FO can carry any network signal at any speed, and multi-mode FO can carry all current network signals within building.

Physical Cables• Wireless Radio

– Wireless Radio is very expensive, but it can be extremely useful in situations where running cable is prohibitively expensive or not possible. The different types of wireless radio solutions in existence all serve different needs and different ranges. The frequency ranging from 900MHz spread spectrum to 23GHz microwave.

Physical Cables• Wireless IR

– Wireless Infrared is broken down into local area and point-to-point solutions. All infrared solutions require a clear line of sight and are greatly impacted by weather, such as rain or fog, unless they are indoor-only solutions.

– Following is description of three types Infrared solutions:

– Short-distance infra-building LED: These devices are generally aimed at central Infrared Hub that can be mounted on a ceiling for total room coverage.

– Medium-distance infra-building LED: These devices must be aimed in each others general direction because they are highly focused and are limited to fewer than 500 meters.

– Long-distance point-to-point LD: It is laser diode solutions can operate at full network speed for a verity of protocols up to 155Mbps – 500 meters and at 20Mbps or less up to 1200 meters.