1 / 30

Wireless - PowerPoint PPT Presentation

  • Uploaded on

Wireless. Wireless Infrastructures. Wireless Infrastructures. Wireless LAN Predominantly 802.11 IEEE 802.11 A, B, G, N Wireless MAN WiMax 802.16 and its derivatives 802.16-2001 Fixed Broadband Wireless Access (10–63 GHz)

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Wireless' - ledell

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript


Wireless Infrastructures

Wireless infrastructures
Wireless Infrastructures

  • Wireless LAN

    • Predominantly 802.11

      • IEEE 802.11 A, B, G, N

  • Wireless MAN

    • WiMax

      • 802.16 and its derivatives

      • 802.16-2001 Fixed Broadband Wireless Access (10–63 GHz)

      • Current : P802.16m Advanced Air Interface with data rates of 100 Mbit/s mobile & 1 Gbit/s fixed


  • 802.15 assortments

    • 802.15.1 WPAN (Wireless Personal Area Networks)

    • IEEE 802.15.2-2003

      • coexistence of wireless personal area networks (WPAN) with other wireless devices operating in unlicensed frequency bands such as wireless local area networks (WLAN).

    • 802.15.2,

    • 802.15.3-2003 is a MAC and PHY standard for high-rate (11 to 55 Mbit/s) WPANs

    • 802.14.4 (Low Rate WPAN) ZigBee

    • 802.15.5

      • Mesh networking of WPAN

    • 802.16.6 (medical purposes)

      • Body Area Network Technologies. The goal is a low-power and low-frequency short-range wireless standard

Similarities between wlan and lan
Similarities Between WLAN and LAN

  • A wireless LAN is an IEEE 802 LAN.

    • Transmits data using RF carriers vs. data over the wire

    • Looks like a wired network to the user

    • Defines physical and data link layer

    • Uses MAC addresses

  • The same protocols/applications run over both WLANs and LANs.

    • IP (network layer)

    • IPSec VPNs (IP-based)

    • Web, FTP, SNMP (applications)

Current standards 802 11a b g n

54 Mbps


860 Kbps

1 and 2 Mbps

1 and 2 Mbps

11 Mbps




5 GHz


900 MHz

2.4 GHz

2.4 GHz










Current Standards – 802.11a,b,g, n

  • 802.11a

    • Up to 54 Mbps

    • 5 GHz

    • Not compatible with either 802.11b or 802.11g

  • 802.11b

    • Up to 11 Mbps

    • 2.4 GHz

  • 802.11g

    • Up to 54 Mbps

    • 2.4 GHz

  • 802.11n, the newest protocol, utilizes both 2.4-GHz and 5-GHz bands.

    • Datarate varying from 15 -150 Mbps)[

802.11 Ratified

802.11a,b Ratified

802.11g Ratified

  • IEEE 802.11Begins Drafting

802.11g is backwards compatible with 802.11b

802.11n is backward compatible with existing 802.11a/b/g

Radio frequency issues
Radio Frequency Issues

  • As signal strength decreases, so will the transmission rate.

  • An 802.11b client’s speed may drop from 11 Mbps to 5.5 Mbps, to 2 Mbps, or even 1 Mbps.

  • This can all be associated with a combination of factors including:

    • Distance

    • Line of Sight

    • Obstructions

    • Reflection

    • Multpath Reflection

    • Refraction (partially blocked by obstruction)

    • Diffraction (bending of signal)

    • Noise and Interference

Wireless access points
Wireless Access Points

  • An access point (AP) is a WLAN device that can act as the center point of a stand-alone wireless network.

  • An AP can also be used as the connection point between wireless and wired networks.

  • In large installations, the roaming functionality provided by multiple APs allows wireless users to move freely throughout the facility, while maintaining seamless, uninterrupted access to the network.

Wireless bridges
Wireless Bridges

  • The bridges connect hard-to-wire sites, noncontiguous floors, satellite offices, school or corporate campus settings, temporary networks, and warehouses.

  • Example: The Cisco Aironet 1300 Series Wireless Bridge is designed to connect two or more networks that are typically located in different buildings.

  • They can be configured for point-to-point or point-to-multipoint applications.

Service set identifier ssid
Service Set Identifier (SSID)

  • SSID is used to logically separate WLANs.

  • The SSID must match on client and access point.

  • Access point can broadcast SSID in beacon.

  • Client can be configured without SSID.

Basic topologies
Basic Topologies

Basic Infrastructure Topology (BSS)

Peer-to-Peer (Ad Hoc) Topology (IBSS)

Extended Infrastructure Topology (ESS)


WiFi (802.11) Media Access Control

  • As all the devices in the network share the same frequency, to a common Access Point (AP)

  • They cannot all transmit at the same time as their signals will interfere.

  • Therefore, WiFi networks operate in half-duplex, using an access method similar called CSMA/CA.

Access Point

Local area networks lan
Local area networks (LAN)

802.11b/g Channels

  • Adding an AP is also a way to add wireless devices and extend the range of an existing wired system.

  • If a single cell does not provide enough coverage, any number of cells can be added to extend the range.

  • It is recommended that adjacent BSS cells have a 10 to 15 percent overlap.

802.11a Channels

Wireless repeater
Wireless repeater

50% overlap

  • A wireless repeater is simply an access point that isnotconnected to the wired backbone.

  • This setup requires a 50% overlap of the AP on the backbone and the wireless repeater. (So they can reach each other).

  • The user can set up a chain of several repeater access points, however, the throughput for client devices at the end of the repeater chain will be quite low, as each repeater must receive and re-transmit each frame.

Not covered by 802.11 standards

Cisco wlan implementation
Cisco WLAN Implementation devices

  • Distributed WLAN solution

    • Autonomous AP

    • Wireless LAN Solution Engine (WLSE)

  • Centralized WLAN solution

    • Lightweight AP

    • Wireless LAN Controller (WLC)

Cisco offers 2 “flavors” of wireless solutions:

Comparison of the wlan solutions

Autonomous WLAN: devices

Autonomous access point

Configuration of each access point

Independent operation

Management via CiscoWorks WLSE and WDS

Access point redundancy

Lightweight WLAN:

Lightweight access point

Configuration via Cisco Wireless LAN Controller

Dependent on Cisco Wireless LAN Controller

Management via Cisco Wireless LAN Controller

Cisco Wireless LAN Controller redundancy

Comparison of the WLAN Solutions

Why lightweight aps
Why Lightweight APs? devices

  • A WLAN controller system is used to create and enforce policies across many different lightweight access points.

  • With centralized intelligence, functions essential to WLAN operations such as security, mobility, and quality of service (QoS), can be efficiently managed across an entire wireless enterprise.

  • Splitting functions between the access point and the controller, simplifies management, improves performance, and increases security of large WLANs.

Cisco centralized wlan model
Cisco Centralized WLAN Model devices

  • The control traffic between the access point and the controller is encapsulated by Lightweight Access Point Protocol (LWAPP). And encrypted via the Advanced Encryption Standard (AES).

  • The data traffic between the access point and controller is also encapsulated with LWAPP, but not encrypted.

Layer 2 lwapp architecture
Layer-2 LWAPP Architecture devices

  • Access Points don’t require IP addressing

  • Controllers need to be on EVERY subnet on which APs reside

  • L2 LWAPP was the first step in the evolution of the architecture; many current products do not support this functionality

Layer 3 lwapp architecture
Layer-3 LWAPP Architecture devices

  • Access Points require IP addressing

  • APs can communicate w/ WLC across routed boundaries

  • L3 LWAPP is more flexible than L2 LWAPP and all products support this LWAPP operational ‘flavor’

Wireless mesh networking
Wireless Mesh Networking devices

  • Each access point runs the Cisco Adaptive Wireless Path protocol (AWP).

  • AWP allows access points to communicate with each other to determine the best path back to the wired network.

  • After the optimal path is established, AWP continues to run in the background to establish alternative routes back to the roof-top access point (RAP) if the topology changes or conditions cause the link strength to diminish.

Wireless security protocols
Wireless Security Protocols devices

  • Today, the standard that should be followed in most enterprise networks is the 802.11i standard. This is similar to the Wi-Fi Alliance WPA2 standard.

  • For enterprises, WPA2 includes a connection to a Remote Authentication Dial In User Service (RADIUS) database.

Evolution of wireless lan security
Evolution of Wireless LAN Security devices





802.1x EAP

Encryption (WEP)

Wi-Fi Protected Access (WPA)

Wireless IDS

  • Identification and protection against attacks, DoS

  • AES strong encryption

  • Authentication

  • Dynamic key management

  • No strong authentication

  • Static, breakable keys

  • Not scalable

  • Dynamic keys

  • Improved encryption

  • Userauthentication

  • 802.1x EAP (LEAP, PEAP)


  • Standardized

  • Improved encryption

  • Strong, user authentication (e.g., LEAP, PEAP, EAP-FAST)

IEEE 802.11i

WPA2 (2004)

Wi fi protected access

What are WPA and WPA2? devices

Authentication and encryption standards for Wi-Fi clients and APs

802.1x authentication

WPA uses TKIP encryption

WPA2 uses AES block cipher encryption

Which should I use?

Gold, for supporting NIC/OSs

Silver, if you have legacy clients

Lead, if you absolutely have no other choice.

  • Gold

  • WPA2/802.11i

  • EAP-Fast

  • AES

  • Silver

  • WPA

  • EAP-Fast

  • TKIP

  • Lead

  • Dynamic WEP

  • EAP-Fast/LEAP

  • VLANs + ACLs

Wi-Fi Protected Access

Wlan security summary
WLAN Security Summary devices

Enhanced Security

Basic Security

802.1x, TKIP Encryption,

Mutual Authentication,

Scalable Key Mgmt., Etc.

Open Access

40-bit or 128-bit Static WEP Encryption, WPA

No Encryption, Basic Authentication

Public “Hotspots”

Home Use


VirtualPrivateNetwork (VPN)

Business Traveler, Telecommuter

Remote Access