WLAN FundamentalsBy Marc-André Léger

DESS, MASc, PHD(candidate)

Fall 2007

Save the forest

• Please do not print out more than one module at a time as it may evolve…

Course information

• Course Title: Wireless LAN Fundamentals • Course Duration: 45 hours• Course Number: 420-874-LA • Course Credits: 2.00• Course Weighting: 3-0-3

Who am I ?

Marc-André Léger• DESS in Healthcare Informatics (U of Sherbrooke)• MASc in Management Information Systems (UQAM)• PHD candidate in Clinical Sciences at the

University of Sherbrooke – Longueuil Campus (Risk Management in Healthcare)

• 25 years IT experience (Qc, NB, Ontario, USA, France)• 20 years security (DND, DOJ, Space, etc…)

Contact information

• Instructor: Marc-André Léger• Contact: marcandre@leger.ca • Website: www.leger.ca

Course Description• This course provides students with an understanding of

the major concepts involved in Wireless Local Area Networks (WLANs).

• The course will begin with a review of computer networking.

• By the end of the course, students will be able to identify and explain the various components which make up a WLAN, identify the major issues and challenges surrounding wireless networks and describe the wireless LAN architecture.

• The course will conclude with a review of emerging technologies which are likely to impact the use of wireless networks in the near future.

Course ObjectivesUpon successful completion of this course,

a student will be able to:• Explain basic concepts of a network;• Identify the networking media;• Explain the similarities and differences between wireless

technologies; • Identify the various components and topologies involved

in wireless networks; • Identify and explain issues and concepts the impact on

the successful implementation and maintenance of a WLAN;.

• Explain the major WLAN concepts and terms;• Identify major technological developments which impact

WLANs and discuss their impact.

Course evaluation

• A home assignment (Course 3) 30% • An in-class presentation (course10) 20%• A mid-term exam (Course 6) 15%• A final exam (Course 12) 35%

Assignments

1- Planning a WLAN implementation.• Your employer asked you, as Network Manager for the company, to plan the

implementation of a WLAN. • The principal objective is to allow for the implementation of workstations for

the operators of industrial equipment.• The solution must also allow for the use of wireless access in the corporate

conference rooms and in the office. • The instructors acts as the CIO and is your internal customer. He expects a

7 to 10 page (1.5 spacing, courier 12 font, 3cm margins all around) report including:

– a title page– an executive summary– a table of contents– an analysis of the current situation– a description of the requirements– the solutions that where considered (at least 2)– the proposed solution– a recommendation to the CIO.– a bibliography

2- In-class presentation

• The CIO asks you to make a presentation to the board of directors (formed of all your classmates) of the WLAN proposed for St Lawrence Sawmill as per corporate purchasing policy.

• The board will evaluate your proposal using an evaluation template (provided by the instructor).

Business Case

Saint Lawrence Sawmill

Business case• Available online: www.leger.ca • Sawmill producing lumber wood• In La Tuque, in the Mauricie region• 800 relatively unskilled workers• Operates uninterrupted 24x7 (3 shifts of 8 hours)• Part of a great industrial group, Bois St-Laurent• HQ in Montreal•  In May 2006 it was purchased by SWP (Svirge

Wood Products)

Current technological environment

• Minicomputer (IBM AS400) • Custom built information system created

by an external consultant • Five workstations (PC) for administration

used for the integration of data into the information system

• Printer for reports• Oracle

Project name: SIGES

• Corporate management information system connected to the corporate management system (ERP or ertreprise ressource planning), SAP, located in Sweden ()

Proposed architecture• Server: SUN Microsystems Sun Fire E20K• Storage: Sun Microsystem Sun Storage Teak 9900• 100 pc's for factory (adapted for use in factory)• 10 workstations (Windows - INTEL) for management• printers for reports• Local area network 100-baseT commuted (switched)

with high bandwith for the management network• Wireless Local area network in factory• Wireless Local area network access for conference

rooms• Virtual private network (VPN) with Sweden via Internet

Budget of the project of change (Maximum allocated)

• Equipment: 500 000$• Wiring and infrastructure: 100 000$• Service Contracts for the equipment: 50 000$ per

year as of the second year• Software: 150 000$ + recurring license fees of 15

000$ per year • Configuration and conversion of the data: 150 000$• Training: 50 000$• Consulting services: 350 000$• Installation: 200 000$• Contingencies (10%): 150 000$

Layout

Module 1

The WLAN Challenge

Accessible knowledge when and where it is needed

for authorized users

What is a computer ?• A computer is a machine which manipulates

data according to a list of instructions which makes it an ideal example of a data processing system.

What is a Network ?

• A computer network is the connection of two or more computers by some medium.– wire (twisted pair)– fiber optic cable (less susceptible to

electromagnetic interference)– radiowaves

Origin of Networks• 1930’s electrical engineers

used a devise called Network Analyzer

• Earliest mainframes were put on networks in order to share computing power.

4 node ARPANET in 1969: commissioned by USA DoD for research into networking

Why do we use Networks?

• Efficiency• Necessity• Convenience

Basic concepts of a network

Networking Terminology

• NOS (network operating system)– In the early days of PC computing, most

PC’s could not communicate on a network with other computers. That gave rise to two distinct terms: the stand-alone operating system (OS), which could not communicate on a network, and the networking OS, which could communicate on a network.

Networking Terminology• Networking Hardware

– is a generic term that describes all the physical components of a network, such as NIC, cable, and any related connectors. Any device or physical component that is used to connect computers in a network is considered to be network hardware.

• Networking Software– is the software programs used to run the network.

These programs include the NOS and all client/server networking software programs, such as shared applications.

Types of Networks• LAN (local area network)

– is contained within a company or department and located in a single geographic area.

• WAN (wide area network)– spans multiple geographic areas and is usually

connected by common telecommunication carriers• MAN (metropolitan area network)

– a network that is within the boundaries of a city, campus, or town, but is larger than a LAN.

OSI Model• ISO (international organization for standardization)

– communication problems between networks became difficult. The wide variety of hardware and software made communications between systems nearly impossible.

• OSI (open system interconnection)– by examining existing protocols, such as TCP/IP

(transmission control protocol/internet protocol, SNA (systems network architecture), DECNET (digital equipment corporation), the OSI recommended a seven layer network model called the OSI model.

The ISO OSI Model

Physical

Data link

Network

Transport

Session

Presentation

Application

Media signal and binary transportation

Physical addressing (MAC)

Path determination and logical addressing (IP)

End-to-end connections and reliability

Inter-host communication

Data representation and encryption

Network process to application

bits

Frames

Packet

Segment

Data

Data

Data

Networking hardware

Network Topologies

NIC (network interface card)

• The NIC is a physical component that connects to the internal hardware of the computer system.

• The NIC forms a physical connection to the network media.

Physical Addresses• The NIC manufacturer burns the physical address or

media access control (MAC) address into the network card during the manufacturing process.

Logical Addresses• When TCP/IP is used on a network, the logical

address is known as an IP address.• Routers utilize the IP address to route packets to the

correct network segment.• Software, not hardware, implements IP addresses.• Routers use the logical Network layer software

address to route packets to the appropriate network segment.

Logical Addresses• An IP address has 32 bits divided into four octets.• To make the address easier to read, people use decimal

numbers to represent the binary digits.– 192.168.1.1 =

11000000.10101000.00000001.00000001• For communications to travel from one place to another,

routers must be able to track and interpret IP addresses.

Hub• A hub is a generic connection device used to tie several networking

cables together to create a link between different stations on a network.

Hub• Hubs that are plugged into electric power are

called active hubs.– They usually amplify or repeat signals that pass

through them.– Because they have multiple inbound and outbound

connections, these hubs are also known as multi-port repeaters.

• A hub that merely connects different cables on the network and provides no signal regeneration is called a passive hub and is not a repeater.

Switch

Router• Routers connect multiple segments and multiple networks.• They provide filtering and network traffic control.

InterNet

Design drivers

• A survivable and robust inter-connected computer network

Core concepts• Connected hosts, ports and services. • A set of open protocols for

internetworking, eg TCP/UDP/IP• Connection-oriented (TCP) and

connection-less (UDP) datagram protocols• A choice of physical layers (copper, fibre

optic) and network layers (Ethernet, ATM, Token Ring: 802.x protocols)

• A ‘dumb’ network with smart applications.

Eras– Pre-history Era (1945-1970)– University Era (1970-1989)– Commercial Era (1989 – )

• The evolution of the internet is a series of cycles …

Some Key Players

• Vannevar Bush – “Memex” information store (1945)

• Ted Nelson and Douglas Engelbart - Hypertext (1960s)

• Vince Cerf – TCP/IP (1970s)• Bob Metcalfe – Ethernet (1970s)• Tim Berners-Lee – HTTP (1989)

Growth of internet since 1995• (# sites surveyed by: Netcraft.com)

Cycles in the latest Internet boom

The ubiquitous Internet

The Internet connecting multiple devices.

Market Share for top servers

Networking Media

LAN and Physical LayerMany topologies support LANs, as well as many different physical media.

This figure shows a subset of physical layer (layer 1) implementations that can be deployed to support Ethernet.

EthernetEthernet is the most widely used LAN technology.

Ethernet was first implemented by the Digital, Intel, and Xerox group (DIX).

DIX created and implemented the first Ethernet LAN specification, which was used as the basis for the Institute of Electrical and Electronics Engineers (IEEE) 802.3 specification, released in 1980.

Ethernet Media and Connector Requirements

The cables and connector specifications used to support Ethernet implementations are derived from the EIA/TIA standards.

The categories of cabling defined for Ethernet are derived from the EIA/TIA-568 SP-2840 Commercial Building Telecommunications Wiring Standards.

Networks with a combination of 10- and 100-Mbps traffic use Category 5 UTP to support Fast Ethernet.

Connection MediaThe connector on a NIC may not match the media to which it needs to connect.

An interface may exist for the DB-15 pin attachment unit interface (AUI) connector.

The AUI connector allows different media to connect when used with the appropriate transceiver.

A transceiver is an adapter that converts one type of connection to another.

A transceiver will usually convert an AUI to an RJ-45, a coax, or a fiber optic connector.

STP

Shielded Twisted Pair (STP)

• STP cabling includes metal shielding over each individual pair of copper wires. This type of shielding protects cable from external electromagnetic interference.

UTP

UTP ImplementationEIA/TIA specifies an RJ-45 connector for UTP cable.

The letters RJ stand for registered jack and the number 45 refers to a specific wiring sequence.

The RJ-45 transparent end connector shows eight colored wires.

Four of the wires, T1 through T4, carry the voltage and are called tip.

The other four wires, R1 through R4, are grounded and are called ring.

The RJ-45 connector is the male component, which is crimped on the end of the cable.

When a male connector is viewed from the front, the pin locations are numbered from 8 on the left to 1 on the right.

UTP ImplementationThe jack is the female component in a network device, wall outlet, or patch panel.

UTP ImplementationThe punch-down connections at the back of the jack are where the Ethernet UTP cable connects.

UTP ImplementationFor electricity to run between the connector and the jack, the order of the wires must follow T568A or T568B color code found in the EIA/TIA-568-B.1 standard

UTP ImplementationIf the two RJ-45 connectors of a cable are held side by side in the same orientation, the colored wires will be seen in each.

If the order of the colored wires is the same at each end, then the cable is a straight-through.

UTP ImplementationStraight-through :

Switch to router Switch to PC or server Hub to PC or server

Cross-over:Switch to switch Switch to hub Hub to hub Router to router PC to PC Router to PC

Roll-over: Terminal to console port

Unshielded & Shielded Twisted Pair Cabling StandardsCat 1: Currently unrecognized by TIA/EIA. Previously used for POTS telephone

communications, ISDN and doorbell wiring. Cat 2: Currently unrecognized by TIA/EIA. Previously was frequently used on 4 Mbit/s

token ring networks. Cat 3: Currently defined in TIA/EIA-568-B, used for data networks using frequencies up to

16 MHz. Historically popular for 10 Mbit/s Ethernet networks. Cat 4: Currently unrecognized by TIA/EIA. Provided performance of up to 20 MHz, and

was frequently used on 16 Mbit/s token ring networks. Cat 5: Currently unrecognized by TIA/EIA. Provided performance of up to 100 MHz, and

was frequently used on 100 Mbit/s ethernet networks. May be unsuitable for 1000BASE-T gigabit ethernet.

Cat 5e: Currently defined in TIA/EIA-568-B. Provides performance of up to 100 MHz, and is frequently used for both 100 Mbit/s and gigabit ethernet networks.

Cat 6: Currently defined in TIA/EIA-568-B. It provides performance of up to 250 MHz, more than double category 5 and 5e.

Cat 6a: Future specification for 10 Gbit/s applications. Cat 7: An informal name applied to ISO/IEC 11801 Class F cabling. This standard

specifies four individually-shielded pairs (STP) inside an overall shield. Designed for transmission at frequencies up to 600 MHz.

Coaxial cable

Optical fiber

Single mode fibre

Multimode fibre

Fibre connector

Look at similarities and differences between wireless technologies

Categories of wireless implementations

• Broadcasting • Amateur radio • Communication radio • Cordless telephony

– DECT (Digital Enhanced Cordless Telecommunications)

• Cellular systems – 0G – 1G – 2G – 3G – 4G

• Short-range point-to-point communication – Wireless microphones – Remote controls – IrDA – RFID (Radio Frequency Identification) – Wireless USB – DSRC (Dedicated Short Range Communications) – EnOcean

• Wireless sensor networks – ZigBee – EnOcean

• Personal area networks – Bluetooth – Ultra-wideband (UWB from

WiMedia Alliance). • Wireless computer networks

– Wireless Local Area Networks (WLAN)

• IEEE 802.11 branded as WiFi • HIPERLAN

– Wireless Metropolitan Area Networks (WMAN) and Broadband Fixed Access (BWA)

• LMDS • WiMAX • HIPERMAN

Wireless History

1924: First Mobile Radio Telephone

1901: First radio reception across the Atlantic Ocean

Early Cellular Systems• 1940s-50s: cellular concept discovered (AT&T)• 1 st Generation: Analog:

– AMPS: FDMA with 30 KHz FM-modulated voice channels.

– 1983: The first analog cellular system deployed in Chicago: saturated by 1984,

– FCC increased the cellular spectral allocation from 40 MHz to 50 MHz.

• Two 25MHz channels: DL and UL (FDD) – AT&T moved on to fiber optics in ‘80s.

• 2 nd generation: digital: early 90s– higher capacity, improved cost, speed, and power

efficiency of digital hardware

Wireless Evolution Timeline

Modern Wireless Systems

Peak

Modern Wireless Systems (by Segment)

End of session 1

Questions ?