Chapter 2 Flashcards
help ensure different products from different vendors function in the same capacity.
Advantages of standards:
Standards
ensures devices from one vendor will function with those from other vendors
Interoperability
any vendor can create a device based on a recognized standard and will add additional features to their products to make them more competitive (increases value for users)
Competition
Common practices that the industry follows for various reasons
De facto standards
Official standards
De jure standards
Usually industry-sponsored organizations that want to promote a specific technology
Consortia-created standards
To reduce confusion, in 2007 IEEE combined the standards and amendments into a single standard
IEEE 802.11-2007
All types of light
Light spectrum
Can be used for wireless transmissions, Invisible
Infrared light
Device that transmits a signal
Emitter
Device that receives a signal
Detector
requires that the emitter and detector be directly aimed at one another in a line of sight (LoS) path
Directed transmission
relies on reflected light
Emitters have a wide-focused beam instead of narrow and are pointed at a ceiling (reflection point)
Diffused transmission
can penetrate through objects
Provides mobility
Radio waves travel longer distances
Can be used indoors and outdoors
Radio waves can travel at much higher speeds than infrared transmissions
IEEE 802.11 standard outlining radio wave transmissions has become preferred method for wireless LANs
Radio Wave Transmissions
amendment added two higher speeds (5.5 Mbps and 11 Mbps) to original 802.11 standard
Uses ISM band
Supports wireless devices up to 107 meters (350 feet) apart
802.11b
official term given to a wireless device
Station (STA)
theoretical maximum rated speed of a network
Data rate
measure of how much actual data can be sent per unit of time across a network
Throughput
standard specifies maximum rated speed of 54 Mbps
Range is less than that of 802.11b
IEEE 802.11a
Effort to combine best features of 802.11a and 802.11b
Data transfer rates to 54 Mbps
Support devices up to 115 meters apart
IEEE 802.11g
Speed: up to 600 Mbps
Coverage area: Double the indoor range and triple the outdoor range
Interference: uses different frequencies to reduce interference
Security: requires the strongest level of wireless security
IEEE 802.11n
Connects computer to network so that it can send and receive data
Network interface card (NIC)
Portable laptop computers often support wireless NICs in different form factors
PCMCIA (Personal Computer Memory Card International Association) cards
enhanced type of PC Card that includes a bus mastering feature (allows a controller on the bus to talk to other devices or memory bypassing the CPU)
CardBus
Wireless connection management utility (introduced in Windows XP) that operates as a Windows service
Automatically determines which wireless network to connect to based on default settings and preference set by user
Wireless Zero Configuration (WZC) service:
replace WZC in Windows 7
WLAN AutoConfig
Two basic function:
Base station for wireless network
Bridge between wireless and wired networks
Access Points
Considered independent because they are separate from other network devices
Have intelligence to manage authentication, encryption, and other functions for wireless clients
Also called fat access points
Autonomous Access Points
Does not contain management and configuration functions
Those features are contained in a central device called wireless LAN controller (WLC) or wireless switch
Lightweight Access Points
used to manage multiple WLCs at remote sites from a central location
Remote office WLAN controller
communicates with the next closest mesh access point
Mesh Access Points
created by dozens or even hundreds of mesh access points
Also known as wireless mesh routers (function in a similar manner to routers)
Only one mesh AP must be physically connected to the wired network
Wireless mesh network (WMN)
connects mesh access points to an Internet connection
Backhaul wireless mesh network
Connects two network segments together
Even if they use different types of physical media
Bridge
used to connect a wired network segment to a wireless network segment
Does not function as a an access point
Only supports wired devices, not any other wireless devices
Wireless workgroup bridge
Connects two or more wired or wireless networks together that are separated by a longer distance
Remote wireless bridge
can only communicate with other bridges not in root mode
Root mode: Root bridge
Can only transmit to another bridge in root mode
Non-root mode
Extend distance between LAN segments
Placed between two other bridges
Repeater mode
Functions as standard AP
Access point mode
network device that acts as an entrance to another network
Gateway
provides encryption and authentication services for a wireless network
Typically serves as the entry point to the wired network
Relieves an AP from burden of encryption and authentication
Enterprise Encryption Gateways (EEG)
Combines features of an AP, firewall, router, DHCP server into a single hardware device
Residential WLAN Gateway
computer can scan for a newly installed WCN capable device
Windows Connect Now (WCN)
Devices that obtain power through the unused wires in a standard UTP Ethernet cable
Eliminates the need to install electrical wiring where devices might need to be located
Power over Ethernet (PoE) Devices
