AG 3100Glossary of Terms 303Glossary of Terms802.11xRefers to a family of specifications developed by the IEEE on page 308 for wireless LAN technology. 802.11 specifiesan over-the-air interface between a wireless client and a base station, or between two wireless clients. The IEEE onpage 308 accepted the specification in 1997. There are several specifications in the 802.11 family:802.11Applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either Frequency HoppingSpread Spectrum (FHSS on page 307) or Direct Sequence Spread Spectrum (DSSS on page 305).802.11aAn extension to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. 802.11a uses anOrthogonal Frequency Division Multiplexing (OFDM on page 310) encoding scheme rather than FHSS or DSSS.802.11b(also referred to as 802.11 High Rate or Wi-Fi™ on page 316) An extension to 802.11 that applies to wireless LANsand provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1 Mbps) in the 2.4 GHz band. 802.11b uses onlyDSSS on page 305. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionalitycomparable to Ethernet.802.11gApplies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.802.1QAn IEEE standard for providing a virtual LAN capability within a campus network. 802.1Q establishes a standardformat for frame tagging (Layer 2 VLAN markings), enabling the creation of VLANs that use equipment frommultiple vendors.10/100 EthernetSee Ethernet on page 306.AAA(Authentication, Authorization, and Accounting) A combination of commands used by Nomadix Gateways toauthenticate, authorize, and subsequently bill subscribers for their use of the customer’s network. When a subscriberlogs into the system, their unique MAC address is placed into an authorization table. The system then authenticates thesubscriber’s MAC address and billing information before allowing them to access the Internet and make onlinepurchases. See also, MAC Address on page 309.Access ConcentratorA type of multiplexor that combines multiple channels onto a single transmission medium in such a way that all theindividual channels can be simultaneously active. For example, ISPs use concentrators to combine their dial-upmodem connections onto faster T-1 lines that connect to the Internet. Concentrators are also used in Local AreaNetworks (LANs) to combine transmissions from a cluster of nodes. In this case, the concentrator is often called a hub.Access RouterA router at a customer site, which connects to the network service provider. Also known as a Customer PremisesEquipment (CPE) router. See also, Router on page 312.