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TIMTIM
Traffic Indication Map. An element in all 802.11 beacons when a client has frames buffered in the AP.
The buffered frames are broadcasted or multicasted at each DTIM, when all power-saving clients
expecting this data should be awake. See also DTIM.
TKIP
Temporal Key Integrity Protocol. Generates new keys every 10 kb of payload traffic.
Tx
Transmit.
USB
A high-speed bidirectional serial connection between a PC and a peripheral that transmits data at the
rate of 12 megabits per second. The new USB 2.0 specification provides a data rate of up to 480 Mbps,
compared to standard USB at only 12 Mbps. 1394, FireWire and iLink all provide a bandwidth of up to
400 Mbps.
VLAN
Virtual LAN. A networking mechanism that makes clients appear as if they are connected to the same
network, even if they are physically located on different LAN segments. Cisco WLAN Solution recom-
mends that you assign one set of VLANs for WLANs and a different set of VLANs for mobility groups to
ensure that Cisco Wireless LAN Controllers properly route VLAN traffic.
VoIP
Voice transmission using Internet Protocol to create digital packets distributed over the Internet. VoIP
can be less expensive than voice transmission using standard analog packets over POTS (Plain Old
Telephone Service).
Volatile RAM
Volatile Random Access Memory. The basic form of computer memory, which can be accessed
randomly. In the Cisco WLAN Solution products, the Volatile RAM contains the active settings for
current operations. Upon reboot, the Volatile RAM is cleared, and the configurations stored in the
NVRAM are copied into the Volatile RAM. (See also NVRAM.)
VPN
A type of technology designed to increase the security of information transferred over the Internet. VPN
can work with either wired or wireless networks, as well as with dial-up connections over POTS. VPN
creates a private encrypted tunnel from the end user's computer, through the local wireless network,
through the Internet, all the way to the corporate servers and database.
WAN
A communication system of connecting PCs and other computing devices across a large local, regional,
national or international geographic area. Also used to distinguish between phone-based data networks
and Wi-Fi. Telephone networks are considered WANs and Wi-Fi networks are considered Wireless Local
Area Networks (WLANs).
War Chalki ng
Marking symbols on sidewalks and walls to indicate nearby access points. This allows other
802.11-equipped clients to connect to the Internet using other peoples’ access points. This practice was
inspired by hobos during the Great Depression who used chalk marks to indicate friendly homes.