CCNA CHAPTER 17 BY jetarvind kumar madhukar

Release 16/7/2009 Jetking Infotrain Ltd.

Wireless LANs

Chapter 17

Release 16/7/2009 Jetking Infotrain Ltd.Chapter 1

Chapter Objectives

Explain Wireless LAN concept Explain Wireless LAN security Deploy WLANs


Recall - I IPv6 supports the features of the security protocol,

provides a way to change addresses that are assigned to the hosts, provides globally unicast addressing removes the need for NAT/PAT. In addition, it has many tools to help with the transition from IPv4 to IPv6.

You can abbreviate the IPv6 address by neglecting the leading 0's in every block or putting (::) in place of continuous hex 0s.


Recall - II A prefix includes some value followed by a slash and a

prefix length. In the RS/RA process, the host sends an IPv6 RS

multicast message to all the routers to identify the IPv6 prefix used on the subnet and IPv6 address of the default router on the subnet. The router replies by sending RA message.


WLAN Concept Wireless LANs are used for Laptops. The users may can

connect to a network or Internet when required.


Modes of 802.11 Wireless LANs

WLANs use the following modes for communication. Ad hoc mode Infrastructure mode


Ad hoc Mode

This mode is used if a wireless device needs to communicate with only a single device or few devices for a short period of time. In ad hoc mode, devices directly send WLAN frames to each other.


Infrastructure mode This mode is used if a wireless device needs to

communicate over the entire network. The Infrastructure mode supports the following two types

of service sets: Basic Service Set (BSS) Extended Service Set (ESS)


Wireless Encoding

When an AP or a WLAN NIC transmits data, it modulates the amplitude, phase and frequency of the signal to encode the data into binary 0 or 1. The classes that can be used to encode the data are as follows: Frequency Hopping Spread Spectrum (FHSS) Direct Sequence Spread Spectrum (DSSS) Orthogonal Division Multiplexing (OFDM)


Coverage Area, Speed and Capacity of WLANs

The coverage area of a WLAN is the space in which WLAN devices communicate successfully. The AP creates a coverage area for the WLAN depending on the following factors: Power transmitted by AP Materials and their locations Antennas Other factors


Wireless LAN Security

WLAN have some unique security requirements because of the vulnerabilities introduced by WLAN which do not exist in Ethernet LANs.

The following are WLAN security standards: Wired Equivalence Privacy (WEP) SSID Cloaking and MAC Filtering Cisco Interim Solution between WEP and 802.11i Wi-Fi Protected Access (WPA) IEEE 802.11i (WPA-2)


Configuring APs

APs are installed and connected to high-speed Internet at home.

The following parameters are used for configuring customer-grade and enterprise-grade APs: IEEE standard Wireless channel Service Set Identifier Transmit power


Cisco's Unified Wireless Solution - I

Organizations today implement the following wireless solutions: Mesh Architecture - In this architecture each node

which is an access point is connected to another node to transmit data between the nodes. Cisco's mesh networks use the devices such as: Root Access Point (RAP) Mesh Access Point (MAP)


Cisco's Unified Wireless Solution - II

Lightweight Access Point protocol (LWAPP) - It is used to communicate with WLAN systems designed by IETF.

Adaptive Wireless Path Protocol (AWPP)- It is a new wireless LAN protocol developed by Cisco. Even when the best path is established, AWPP continues to run in the background to establish alternative path ready in RAP so that it can use when the established link fails.


Summary - I WLAN uses wireless connection to connect mobile users

to a LAN. WLAN uses a device called AP (Access Point) for the

data transmission. IEEE has defined four major WLAN standards, namely

802.11, 802.11a, 802.11b, and 802.11g. WLANs use one of the two modes namely ad hoc or

Infrastructure modes. Ad hoc mode sends the frames directly between the

devices, whereas the Infrastructure mode uses the AP (Access point) for frame transmission.


Summary - II Infrastructure mode uses two type of service set namely

Basic Service Set (BSS) and Extended Service Set (ESS).

WLAN uses the following three general classes to encode the data: Frequency Hopping Spread Spectrum (FHSS) Direct Sequence Spread Spectrum (DSSS) Orthogonal Frequency Division Multiplexing (OFDM)


Summary - III You can measure the WLAN signals easily in

comparison to other undesired signals in the same space using Signal-to-Noise Ratio (SNR). For sending data successfully through WLAN, the SNR must be high.

A device which is near to the AP will pass the data at higher speed. The device which is at the edge of the coverage area will transmit the data at lower speed.


Summary - IV

The AP creates a coverage area for the WLAN depending on the following factors Power transmitted by AP Materials and their locations Antennas

WLAN can have the following threats which are suggested by Cisco authority: War drivers Hackers Employees Rogue AP


Summary-V

WLAN uses the following three types of tools to reduce the attacks: Mutual Authentication Encryption Intrusion Tools

WEP is the original 802.11 security standard that provides the authentication and encryption services.

Education

CCNA CHAPTER 17 BY jetarvind kumar madhukar