© 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialBCMSN 6 - 5 1 Implementing...

© 2006 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialBCMSN 6 - 5 1

Implementing Wireless LANs

BCMSN Module 6 Lesson 5


Objectives Describe the implementation of the Cisco autonomous and

lightweight WLAN solution that is part of the Cisco implementation of WLANs

Describe how LWAPP is used in the Cisco lightweight WLAN implementation

Describe the components of the Cisco WLAN implementations Describe Cisco Unified Wireless Networks Describe Cisco Aironet access points and bridges Describe PoE for access points and IP phones Identify the types of antennas to use in WLAN environments Explain multipath distortion Describe the decibel calculation Explain the established EIRP guidelines


Cisco WLAN Implementation

Distributed WLAN solutionAutonomous AP

Wireless LAN Solution Engine (WLSE)

Centralized WLAN solutionLightweight AP

Wireless LAN Controller (WLC)

Cisco offers 2 “flavors” of wireless solutions:


Distributed WLAN Solution Components

Autonomous access points

Network Infrastructure

Wireless Domain Services (WDS) – optional

Wireless LAN Solution Engine (WLSE) – optional

Acess Control Server (ACS) – optional


Centralized WLAN Solution Components

Lightweight access points

Network Infrastructure

Wireless LAN controller (WLC) – required

Wireless Control System (WCS) – optional

Location appliance – optional

Acess Control Server (ACS) – optional


Cisco Centralized WLAN Model


Why Lightweight APs?

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


Wireless LAN Solution Comparison

Distributed SolutionCentralized

Solution

Autonomous access points

Lightweight access points

Wireless Domain Services (WDS)

WLAN controller

WLAN Solution Engine (WLSE)

WLAN Control System (WCS)

PoE switches, routers

PoE switches, routers

DHCP, DNS, AAA DHCP, DNS, AAA


Self Check

1. What is the primary difference between the distributed and centralized solutions offered by Cisco for WLANs?

2. Which solution uses autonomous access points and a Wireless LAN Solutions Engine?

3. What types of functions are handled by the AP in the Centralized model?


LWAPP


Layer-2 LWAPP Architecture

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


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’

Layer-3 LWAPP Architecture


Association of Access Point to WLAN Controller

Access points use LWAPP in Layer 2 and Layer 3 mode to associate to the WLAN controller.

In Layer 3 mode, the access point sends an LWAPP Discovery Request to the controller management IP address via a directed broadcast.

The controller responds with a Discovery Response from the manager IP address that includes the number of access points currently associated to the access point manager interface.

The access point chooses an access point and sends the Join Request.

All subsequent communication is to the WLAN controller access point manager IP address.


LWAPP Controller Discovery

LWAPP Discovery Request—AP issues 1 or more of these messages to find controllers (sent to Management Interface IP Address)

LWAPP Discovery Response—Any controller receiving an LWAPP Discovery Request responds with this message to the requesting AP


WLAN Controller Selection Algorithm

LWAPP Discovery Response contains important information from the WLAN Controller:

Controller sysName, controller type, controller AP capacity, current AP load, “Master Controller” status, AP Manager IP address(es) and number of APs joined to the AP Manager

After an “LWAPP Discovery Interval” timer expires, the AP selects a controller to join using the following decision criteria:

1. If AP has been previously configured with a primary, secondary, and/or tertiary controller, the AP will attempt to join these first (specified in the Controller sysName)

2. Attempt to join a WLAN Controller configured as a “Master” controller

3. Attempt to join the WLAN Controller with the greatest excess AP capacity This last step provides the whole system with dynamic AP load-

balancing


LWAPP Controller Join Process

LWAPP Join Request—AP sends this messages to selected controller (sent to AP Manager Interface IP Address)

LWAPP Join Response—If controller validates AP request, it sends the LWAPP Join Response indicating that the AP is now registered with that controller


Self Check

1. What is the difference between an LWAPP Layer 2 frame and an LWAPP Layer 3 frame?

2. Which LWAPP mode does not require the APs to have IP addresses, but does require that the controller and AP be in the same broadcast domain?

3. Which device sends an LWAPP Discovery Request?

4. If multiple controllers respond to an AP, how does the AP select a controller?


Cisco Unified Wireless Network


Cisco Unified Wireless Network

Unified cellular and Wi-Fi VoIP. Advanced threat detection, identity networking, location-based security, asset tracking and guest access.

Unified Advanced Services

Same level of security, scalability, reliability, ease of deployment, and management for wireless LANs as wired LANs.

World-Class Network Management

Integration into all major switching and routing platforms. Secure innovative WLAN controllers.

Network Unification

Mobility Platform Ubiquitous network access in all environments. Enhanced productivity. Proven platform with large install base and 63% market share. Plug and Play.

90% of Wi-Fi silicon is Cisco Compatible Certified. “Out-of-the-Box” wireless security.

Client Devices


Cisco Unified Wireless Network Components

Unified built-in support of leading-edge applications, not an afterthought. Cisco Wireless Location Appliance, Cisco WCS, SDN, NAC, Wi-Fi phones, and RF firewalls.

Unified Advanced Services

World Class NMS that visualizes and helps secure your air space. Cisco Wireless Control System (WCS).

World-Class Network Management

Cisco Self-Defending Network

Seamless network infrastructure across a range of platforms. Cisco 4400 and 2000 Wireless LAN Controllers. Future Cisco Catalyst 6500, Series WiSM, ISR, and 3750 integration.

Network Unification

Mobility Platform APs dynamically configured and managed through LWAPP. Cisco Aironet Access Points: 1500, 1300, 1240AG, 1230AG, 1130AG, and 1000. Bridges: 1400 and 1300.

Secure clients that work out of the box. Cisco Compatible client devices & Cisco Aironet clients.

Client Devices


Features Industry’s best range and throughput

Enterprise class security

Many configuration options

Simultaneous air monitoring and traffic

delivery

Wide area networking for outdoor areas

Benefits Zero touch management

No dedicated air monitors

Supports all deployment scenarios

(indoor and outdoor)

Ease of use policy based management

Mobility Platform

Cisco Mobility Access Platforms Indoor Access Points

1130AG 10x0

Indoor Rugged Access Points

1500

1240AG 1230AG

Outdoor Access Points/Bridges

1400 1300

1121G


Power over Ethernet


Power over Ethernet (PoE)

Sending operating power over Category 5 Ethernet cable Power Sourcing Equipment (PSE)

Switches, power injector Powered devices (PD)

Access points, IP phones Up to 15.4W power per port Distances up to 100 meters Alternative: AC power adapter


PoE Delivery

Detection of power requirements

IEEE 802.3af

Cisco proprietary inline power

Two approved methods for “inserting” power into Ethernet cable:

Pair 1,2 & 3,6 Pair 4,5 & 7,8


MidSpan Power Injection

Uses pairs 4,5 & 7,8

Requires 8-wire cabling

Does not extend 100-m total length limit

Not possible for 1000TX


Power Sourcing Equipment

Power injectorAIR-PWRINJ3/AIR-PWRINJ-FIB

Powering switchCisco Catalyst 3560-PS/3750-PS

Cisco Express CE500-LC/CE500-PC

Cisco Catalyst 4500/6500 switch with inline power line cards

Router module NM-16ESW-PWR

Router card HWIC-4ESW-POE

Router with PoE support


PoE Switch

switch(config-if)# power inline {auto | never}

Display PoE statistics

switch# show power inline [interface]

switch# show power inline Available:370.0(w) Used:61.6(w) Remaining:308.4(w)Interface Admin Oper Power Device Class Max (Watts)--------- ------ ------ ------- ---------- ----- ----Gi0/1 auto off 0.0 n/a n/a 15.4Gi0/2 auto on 15.4 Ieee PD 3 15.4Gi0/3 auto off 0.0 n/a n/a 15.4Gi0/4 auto on 15.4 Ieee PD 3 15.4Gi0/5 auto off 0.0 n/a n/a 15.4

PoE interface configuration


PoE Switch Port Status


Self Check

1. What are some examples of Power Sourcing Equipment?

2. What is the IEEE standard for Power over Ethernet?

3. What protocol do Cisco devices use to manage PoE?


Antennas


What is the role of an antenna in the WLAN?

An antenna is a device used to transmit or receive signals.

Antennas convert electrical energy into radio frequency (RF) waves when it transmits, or RF waves into electrical energy when it receives.

The size and shape of antennas are determined primarily by the frequency of the signal they are designed to receive. A high gain antenna is highly focused, whereas a low gain antenna receives or transmits over a wide angle.

An antenna provides the wireless system with three fundamental properties: gain, direction, and polarization.


Antenna Concepts

GainMeasured in dBi (gain over theoretical isotropic)

More gain means focusing in certain directions, limited range of coverage

DirectionalityOmnidirectional antennas (360 degree coverage)

Directional antennas (limited range of coverage)

PolarizationMust match for a link to work properly.


Antenna Theory

A theoretical isotropic antenna has a perfect 360 degree vertical and horizontal beamwidth.

Reference for all antennas.


Omnidirectional Antenna: Dipole Energy lobes “pushed in” from the

top and bottom

Higher gainSmaller vertical beamwidth

Larger horizontal lobe

Typical dipole pattern

Side View(Vertical Pattern)

Top View(Horizontal Pattern)

New Pattern (with Gain)Vertical Beamwidth

2-dBi Dipole "Standard Rubber Duck"


Directional Antenna Lobes are pushed in a certain

direction, causing the energy to be condensed in a particular area.

Very little energy is in the back side of a directional antenna.

Side View(Vertical Pattern)

Top View(Horizontal Pattern)

6.5-dBi Diversity Patch Wall Mount – 55 degrees


Connectorized 5-GHz Antennas

Cisco 5-GHzRubber Antenna

(Flat with Blue Dot)

Cisco 2.4-GHzRubber Antenna(Round no dot)

5-GHz (802.11a) antennas have blue ID markers.

Dual-band (2.4-GHz and 5-GHz) antennas have yellow dots.


Multipath Distortion Multipath distortion (a form of radio degradation) occurs when radio

signals bounce off metal objects in a room, such as metal cabinets or ceiling lights.

Multiple signals at receiver cause distortion of the signal.

As radio waves bounce, they arrive at the receiver slightly delayed, combining with the original signal, causing distortion.

Diversity systems use two antennas in different positions to reduce the degradation.


Effective Isotropic Radiated Power

Transmit power is rated in dBm or mW.

Power coming off an antenna is Effective Isotropic Radiated Power (EIRP).

FCC and ETSI use EIRP for power limits in regulations for 2.4-GHz and 5-GHz WLANs.


Antenna Cable Loss Use cable that is supplied

with the antenna, avoiding long cable runs when possible.

Cisco offers these cables:LMR400-style cables

20 and 50 feet

Total loss of 1.3 and 3.4 dB, respectively

LMR600-style cables

100 and 150 feet

Total loss of 4.4 and 6.6 dB, respectively

Cable Type

2.4-GHzLoss

(db/100 feet)

5.8-GHzLoss

(db/100 feet)

LMR400 6.6 10.8

LMR600 4.4 7.25


Key Conversion Factors:

dBi = dbd +2.14

1dBm = 1.26

3 dBm = 2

6 dBm = 4

10 dBm = 10

20 dBm = 100

30 dBm = 1000

40 dBm = 10000

Antenna Power Calculation


Antenna Power Calculation (cont’d)

EIRP = transmitter power + antenna gain – cable loss

AP output = 100mW = 20dB

cable/antenna = +16dBi = 40

EIGR output = 100*40 = 4000 mW

EIGR output = 20 + 16 = 36 dBi


Power Conversion ExerciseConvert the following dBi to dBd:

10 dBi = _______dBd

3dBi = _______dBd

-5 dBi = ________dBd

-8.14 dBi = _______dBd

Convert the following dBd to dBi:

12 dBd = _______ dBi

3dBd = ________ dBi

-4.14 dBd = _______dBi

-6.86 dBd = ________ dBi


Power Conversion Exercise (cont’d)Calculate the outputs of the following systems:

AP output = 100mW cable/antenna = +16dBi

EIGR output = _______mW EIGR output = _______dBi


EIGR output = _______mW EIGR output = ________dBi


EIGR output = ________mW EIGR output = _________dBi

Calculate the AP output power:

AP output = _______mW cable/antenna = +16dBi

EIGR output = 4 mW EIGR output = _______dBi


EIGR output = 2W EIGR output = _______dBi


EIGR output = 200mW EIGR output = ______dBi


2.4-GHz EIRP Rules for FCC Areas

Point-to-multipoint (WLANs)FCC allows increasing the gain of an antenna/cable system if the transmitter power is reduced below 30 dBm in a 1:1 ratio.

Reduce transmit power below maximum of 30 dBm by 1 dBm and increase antenna/cable system gain by 1-dBi.

Point-to-Multipoint

The above values reflect the 1:1 rule.

Transmitter Power

Transmitter dBm

Maximum Gain

EIRP

FCC Maximum 1 W 30 dBm 6 dBi 36 dBm

Cisco Maximum 100 mW 20 dBm 16 dBi 36 dBm

Reduced Tx Power 20 mW 13 dBm 23 dBi 36 dBm


2.4-GHz EIRP Rules for ETSI Areas

Currently ETSI allows a maximum of 20 dBm EIRP on point-to-multipoint and point-to-point installations—17 dBm maximum transmitter power with 3 dBi in gain attributed to antenna and cable combination.

Reduce transmit power below maximum of 17 dBm by 1 dBm and increase antenna/cable system gain by 1 dBi.

Transmitter Power

Transmitter dBm Maximum Gain

EIRP

ETSI Maximum 50 mW 17 dBm 3 dBi 20 dBm

Cisco Maximum 50 mW 17 dBm 2.2 dBi 19.2 dBm





EIRP Rules: Summary

Frequency [GHz]No. of Channels (26 total)

Channel Identifier

Usage

FCC ETSI

TX PowerAnt. Gain

EIRP EIRP

2.400 – 2.483 3 1, 6, 11Indoor Outdoor

30 dBm 6 dBi 36 dBm 20 dBm

5.150 – 5.250 4 36 – 48 Indoor

only16 dBm 6 dBi 22 dBm 23 dBm

5.250 – 5.350 4 52 – 64 Indoor Outdoor


5.470 – 5.725 11 100 – 140Indoor Outdoor


5.725 – 5.825 4 149 – 161 IndoorOutdoor

30 dBm 6 dBi 36 dBm n/a

5.725 MHz and above currently not allowed in most of Europe


Self Check

1. What 3 fundamental properties does an antenna provide to the wireless system?

2. What is multipath distortion?

3. What is used to measure all other antennas in order to rate them?

4. What is used by the FCC and ETSI for power limits in regulations for WLANs?

5. Describe the difference in coverage of an omnidirectional vs. a directional antenna.


Summary Cisco offers Distributed and Centralized WLAN solutions.

LWAPP is the protocol used between lightweight access points and WLAN controllers.

WLAN components include clients, access points, controllers, management systems, infrastructure devices, and security server.

The Cisco Unified Wireless Network provides a unified enterprise-class wireless solution.

Cisco Aironet access points are available for indoor or outdoor use.

Access points and IP phones can be powered over Ethernet cable.

Characteristics of antennas are directionality, gain, and polarization.

Multipath distortion can cause low quality data transmission.

Antenna and RF power is measured in decibels.

EIRP limits are defined by FCC and ETSI regulations.


Resources

LWAPPhttp://standards.ieee.org (for fee)

Cisco Unified Wirelesshttp://cisco.com/en/US/netsol/ns340/ns394/ns348/ns337/networking_solutions_package.html

Federal Communications Commisionhttp://www.fcc.gov

European Telecommunications Standards Institutehttp://www.etsi.org Wireless LAN Compatibility Association

http://www.wi-fi.org


Q and A


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