Ieee 80211 Wlan (Page 2 of 2) in pdf

IEEE 802.11 WLAN

ART

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Distributed Coordination Function (DCF)

DIFS

Frame

Deferral Period

Random Backoff

Contention Window

Interframe Spacing

Client Authentication

Short IFS (SIFS)

Open

No authentication is used

Used to provide minimal spacing delay between

Pre-shared Encryption Keys

control frames or data fragments

Keys are manually distributed among clients and APs

DCF IFS (DIFS)

Lightweight EAP (LEAP)

Normal spacing enforced under DCF for management

Cisco-proprietary EAP method introduced to provide

and non-fragment data frames

dynamic keying for WEP (deprecated)

Arbitrated IFS (AIFS)

EAP-TLS

Variable spacing calculated to accommodate differing

Employs Transport Layer Security (TLS); PKI

qualities of service (QoS)

certificates are required on the AP and clients

Extended IFS (EIFS)

EAP-TTLS

Extended delay imposed after errors are detected in a

Clients authenticate the AP via PKI, then form a secure

received frame

tunnel inside which the client authentication takes

place (clients do not need PKI certificates)

Encryption Schemes

Protected EAP (PEAP)

Wired Equivalent Privacy (WEP)

A proposal by Cisco, Microsoft, and RSA which employs

Flawed RC4 implementation using a 40- or 104-bit

a secure tunnel for client authentication like EAP-TTLS

pre-shared encryption key (deprecated)

EAP-FAST

Wi-Fi Protected Access (WPA)

Developed by Cisco to replace LEAP; establishes a

Implements the improved RC4-based encryption

secure tunnel using a Protected Access Credential

Temporal Key Integrity Protocol (TKIP) which can

(PAC) in the absence of PKI certificates

operate on WEP-capable hardware

IEEE 802.11i (WPA2)

RF Signal Interference

IEEE standard developed to replace WPA; requires a

Reflection

Scattering

Absorption

new generation of hardware to implement significantly

stronger AES-based CCMP encryption

Quality of Service Markings

WMM

802.11e

802.1p

Platinum

7/6

6/5

Refraction

Diffraction

Gold

5/4

4/3

Silver

3/0

Bronze

2/1

Wi-Fi Multimedia (WMM)

A Wi-Fi Alliance certification for QoS; a subset of

Antenna Types

802.11e QoS

Directional

Radiates power in one focused direction

IEEE 802.11e

Omnidirectional

Official IEEE WLAN QoS standard ratified in 2005;

Radiates power uniformly across a plane

replaces WMM

Isotropic

IEEE 802.1p

A theoretical antenna referenced when measuring

QoS markings in the 802.1Q header on wired Ethernet

effective radiated power

by Jeremy Stretch

v2.2

Ieee 80211 Wlan Page 2

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