CHAPTER 9NETWORK DESIGN & LAN DESIGN

REQUIREMENT FOR A NETWORK DESIGN

Points that must be considered before designing a successful network: Study of the existing & future organizational

network need Proper planning of the required network Planning for the operating system & other

groupware Logical planning of the network Physical planning of the network Cost evaluation of the overall network Future expansion of the network Running & maintenance cost of the network Any security consideration.

ORGANIZATION NEED

Before designing, you may need to study the organization & its need for a computer networks.

Ex: how many computers needed?, where they will be placed? The OS type, etc

You will try to answer these questions & design accordingly.

COST EVALUATION

Is the most dominating factor in designing a network.

There are before design & after design costs. Cost arises: initial purchase of hardware,

software, devices, cables etc Ongoing cost: hardware, salary for

administrators, software & maintenance Best practice to follow: always use the least

costly approach to meet the objectives.

BANDWIDTH REQUIREMENT

Bandwidth represents the capacity of the connection.

Higher bandwidth = better performance Bandwidth requirement depends on types of

application used, audio, video usage, number of users, peak hour usage etc.

PHYSICAL LAYOUT

The physical structure of the building (no of floors, walls etc) influences the network layout.

Involves the positioning of servers, hubs, switches, routers & laying out cables.

Depending on the organizational requirement, 1 or more type of topologies can be used. Mesh topology Star topology Bus topology Ring topology Tree topology Hybrid

NETWORK ARCHITECTURE

Is the logical planning of the network & involves selecting proper protocols, data link technologies & logical divisions into domain & subdomain.

It involves the security & policies issues. Proper logical planning makes administration

task easy. Server/client based architecture is easy to

control & implement security procedures.

NETWORK WIRING CONFIGURATION

Cabling depends on the location of the servers, workstations & structure of the office building.

It is usually done by cabling contractors specialized in it.

Cabling cost depends on the quality & quantity of the cable needed. Apart from the cabling cost, there are installations, connectors, wall plates, jacks & patch panel costs.

NETWORK WIRING CONFIGURATION

FACTOR UTP STP COAXIAL FIBER OPTIC

COST Low Average Average HighINSTALLATION Easy Fairly easy Fairly easy Hard BANDWIDTH CAPACITY

1-155Mbps(normal 10Mbps)

1-155Mbps(normal 10Mbps)

Normal 10Mbps

2Gbps (normal 100Mbps)

NODE CAPACITY PERSEGMENT

2 2 30(10Base2) 100(10Base5)

2

ATTENUATION High High Low Low

CHARACTERISTICS OF THE CABLES

TWISTED PAIR CABLING

Twisted pair also known as 10BaseT, is ideal for small, medium or large networks.

Mostly used for star topology networks & depending on the configuration of the cable it can be of 2 types: Straight-through cable – used

to connect computer to the hub/switch

Cross-over cable – used to connect hub to another hub, switch to another switch (same devices)

THIN COAXIAL CABLING

Also called as 10Base2 & suitable for office network & used for connecting very few computers (10 or less)

They are cost effective & easy to install. In coaxial cabling each computer needs a network

card & T connector, computer at both end needs 50ohm terminator plug.

Commonly used in bus topology network, consisting of baseband & broadband.

Thin coax wire

Diameter=0.25inches, max length=200m

Thick coax wire Diameter=0.5inches, max length=500m

WIRED LAN Used at home or office environment & also called

as Ethernet LAN. Cabling used for this type of LAN is either coaxial

(10Mbps bus topology) or twisted pair (10-100Mbps star topology).

Other suitable media cables are:

10Base2 Thin wire, 0.25’ diameter coaxial cable, 200m

10Base5 Thick wire, 0.5’ diameter coaxial cable, 500m

10BaseT Hub topology (star) with twisted pair cable

10BaseF Hub topology (star) with fiber optic cable

IEEE WIRED LAN STANDARDS

IEEE 802.1 Bridging & Management Covers LAN and MAN architecture

IEEE 802.2 LLC (Logical Link Control) Protocol for data link transmission control governing

addressing, error checking, exchange of packet etc IEEE 802.3 CSMA/CD Access Method IEEE 802.4 Token-Passing Bus Access Method IEEE 802.5 Token-Ring Access Method IEEE 802.6 DQDB Access Method/MAN

Distributed Queue Dual Bus IEEE 802.7 Broadband LAN

IEEE WIRED LAN STANDARDS

IEEE 802.8 Fiber Optic LAN IEEE 802.9 Isochronous LAN (Hybrid Voice/Data

LAN) IEEE 802.10 Security

WIRELESS LANS

Among many wireless LAN technology applications, Wireless LAN is very popular.

It allows users in limited area typically in the same building to communicate without cabling.

Wireless LAN only allows wireless users! Sometimes wired LAN like Ethernet, has

special hub that allows connection to wireless users through Access Point(AP)

Devices like AP communicates to the wired LAN using regular protocols but uses Medium Access Control(MAC) on the wireless part of the LAN (IEEE 802.11 standards)

WIRELESS LANS

Ad hoc wireless LAN is another type of wireless LAN only having wireless users, with no cable based LAN attached.

Wireless Access Point (WAP) – connects to your LAN like other devices & lets any computer connected to it wirelessly thus expanding the LAN.

Wireless Adapter (Wireless NIC) – hardware designed for personal computers & allows the computer to connect to a network through radio waves.

THE BENEFIT OF WIRELESS LAN

Advantages: Mobility (anywhere in building/office) Fast & easy installation Flexibility (any time anywhere) Reduces Ownership Cost Scaling Facility Convenience (no cabling, wiring)

WIRELESS CONFIGURATION

When 2 PC’s are equipped with wireless adapter card, it can be configured to build its own network. (peer to peer)

Access Point is connected to a wired network, each client has access to resource in the server & also to other clients.

Usually supports 15 to 50 clients. Wireless LAN coverage can be extended to cover

wide area if more than 1 AP is installed. Sometimes Extension Point (EP) is used to

connect Aps.

WIRELESS LAN STANDARDS (802.11)

IEEE 802.11 (RF LANs) IEEE 802.11

2.4GHz IEEE 802.11a

Operates at 5GHz IEEE 802.11b

Was the first among 802.11a, 802.11b & 802.11g, slowest among them but cheapest

IEEE 802.11g Newest of the 3 standards, used in hotspots

area. IEEE 802.15 Bluetooth

BLUETOOTH 802.15

Developed by Ericson 1994 to allow laptop computers to make calls over a mobile phone.

Bluetooth Special Interest Group (SIG) is an industry consortium responsible for publishing Bluetooth standards.

Range 10Meters & up to 100meters with power boost.

What it can do : allows to make calls using headset connected to cellular phones, direct link with printers and PC, mp3 players to download music, monitor children, turn off home appliances etc

INFRARED LAN Suitable for indoor access line in the large city

where many personal computers work simultaneously in an office.

Communication is performed between ceiling mounted hub & pc mounted node.

Covers short range communications, useful in areas of high population density as it does not penetrate wall / interfere with other devices in the room.

Used in remote devices. Uses infrared light-emitting diodes (LEDs) to emit

infrared radiation focused by a plastic lens into a narrow beam. (beam is modulated to on, off or encode the data)

Receiver uses silicon photodiode to convert the infrared radiation to an electric current

VIRTUAL LAN IEEE 802.1Q

VLANs allows a single physical LAN to be partitioned into several smaller logical LANs.

It limits the broadcast domain, improve security & performance & ideal for separating industrial automation systems from IT systems.

Consists of a network of computers that behaves as if connected to the same wire althought they may be physically connected to different segments.

To configure, we use the softwares & not the hardwares (more flexibility)

VIRTUAL LAN IEEE 802.1Q

Advantages of Virtual LAN Reduces the broadcast domain (thus reducing

traffic & increases security) Reduces management effort to create sub

networks Reduces hardware requirement Increases control over multiple traffic types Increases network security.

WIRELESS APPLICATION PROTOCOL (WAP)

Is an open international standard for applications that use wireless communication. Its principle application is to enable access to the internet from a mobile phone or PDA.

A WAP browser provides all the basic services of computer based browser but simplified to suit mobile phones.

Websites are converted into Wireless Markup Language (WML) accessed via WAP browser.

Common activities supported : email, tracking of stick market, sports results, news headlines, music downloads.

WIRED LAN

IEEE standards Name

802.1 Bridging & Management

802.2 Logical Link Control

802.3 CSMA/CD Access Method

802.4 Token-Passing Bus Access Method

802.5 Token Ring Access Method

802.6 DQDB Access Method / MAN

802.7 Broadband LAN

802.8 Fiber Optic LAN

802.9 Hybrid Voice / Data LAN

802.10 Security

WIRELESS LAN

IEEE standards Name

802.11 RF LANs

802.11b Wi-Fi

802.15 Bluetooth