802.11 network architecture
TRANSCRIPT
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802.11 Network Architecture802.11 Network Architecture
Chapter 6Chapter 6
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Locating a Wireless LANLocating a Wireless LAN
The client will automatically “listen" to see if there is a wireless LAN within range.
Scanning occurs before any other process, since scanning is how the client finds the network.
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Service Set IdentifierService Set Identifier
A unique, case sensitive, alphanumeric value from 2 - 32 characters long used by wireless LANs as a network name.
SSID is that it must match EXACTLY between access points and clients.
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BeaconsBeacons
Short frames that are sent from the access point to stations (infrastructure mode) or station-to-station (ad hoc mode) in order to organize and synchronize wireless communication on the wireless LAN.
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Passive ScanningPassive Scanning
The process of listening for beacons on each channel for a specific period of time after the station is initialized.
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Active ScanningActive Scanning
The sending of a probe request frame from a wireless station
• Stations send this probe frame when they are actively seeking a network to join.
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Authentication & AssociationAuthentication & Association
The process of connecting to a wireless LAN consists of :
authentication association
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AuthenticationAuthentication
The process through which a wireless node has its identity verified by the network to which the node is attempting to connect.
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AssociationAssociation
The state at which a client is allowed to pass data through an access point
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States of Authentication & AssociationStates of Authentication & Association
Unauthenticated and unassociatedAuthenticated and unassociatedAuthenticated and associated
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Authentication MethodsAuthentication Methods
Open System authentication Shared Key authentication.
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Open System AuthenticationOpen System Authentication
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Shared Key AuthenticationShared Key Authentication
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Authentication SecurityAuthentication Security
Open System authentication is considered more secure than Shared Key authentication.
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Emerging Wireless Security SolutionsEmerging Wireless Security Solutions
802.1x using Extensible Authentication Protocol (EAP).
VPN (Virtual Private Network)
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802.1x and EAP802.1x and EAP
The 802.1x is port-based network access control standard
EAP is a layer 2 protocol that is a flexible replacement for PAP or CHAP under PPP that works over local area networks.
In the 802.1x standard model, network authentication consists of three pieces:
the supplicant, the authenticator, the authentication server.
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802.1x and EAP802.1x and EAP
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VPN SolutionsVPN Solutions
VPN technology provides three levels of security:
user authenticationencryption data authentication.
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Service SetsService Sets
Basic service setExtended service setIndependent basic service set
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Basic Service Set (BSS)Basic Service Set (BSS)
A basic service setconsists of only one access point and one or more wireless clients
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Extended Service Set (ESS)Extended Service Set (ESS)
Two or more basic service sets connected by a common distribution system.
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Independent Basic Service Set (IBSS)Independent Basic Service Set (IBSS)
Independent basic service set is also known as an ad hoc network
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RoamingRoaming
Roaming in an ESS
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ReassociationReassociation
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Access point with an external VPN serverAccess point with an external VPN server