812 Appendix F:Glossary
NN47250-500 (Version 03.01)
Diffserv Differentiated services. An architecture for providing different types or levels of service for
network traffic. Diffserv aggregates flows in the network so that routers and switches need to distinguish only
a relatively small number of aggregated flows, even if those flows contain thousands or millions of individual
flows.
digital certificate A document containing the name of a user (client) or server, a digital signature, a
public key, and other elements used in authentication and encryption. See also X.509.
digital signature The result of encrypting a hash of a message or document with a private key. A digital
signature is used to verify the authenticity of the sender and the integrity (unaltered condition) of the message
or document. See also hash.
Digital Signature Algorithm See DSA.
direct-sequence spread-spectrum See DSSS.
domain (1) On the Internet, a set of network addresses that are organized in levels. (2) In Microsoft
Windows NT and Windows 2000, a set of network resources (applications, printers, and so forth) for a group
of users (clients). Clients log into the domain to access the resources, which can be located on a number of
different servers in the network.
domain policy A collection of configuration settings that you can define once in WLAN Management
Software and apply to many WLAN—Security Switch (WSSs). Each Mobility Domain group in the network
has a default domain policy that applies to every WSS in the Mobility Domain. See also Policy Manager.
DSA Digital Signature Algorithm. The public-key algorithm used to sign X.509 certificates.
DSSS Direct-sequence spread-spectrum. One of two types of spread-spectrum radio technology used in
wireless LAN (WLAN) transmissions. To increase a data signal’s resistance to interference, the signal at the
sending station is combined with a higher-rate bit sequence that spreads the user data in frequency by a factor
equal to the spreading ratio. Compare FHSS.
DTIM Delivery traffic indication map. A special type of traffic indication map (TIM) element in a beacon
frame that occurs only when a station in a basic service set (BSS) is in power-save mode. A DTIM indicates
that any buffered broadcast or multicast frames are immediately transmitted by an AP.
DXF format A tagged data representation, in ASCII format, of the information contained in an AutoCAD
drawing file.
dual-homed connection A redundant, resilient connection between an AP and one or more
WLAN—Security Switches (WSSs). The connection can consist of two direct physical links from both AP
ports to one or two WSSs, one or more distributed links through an intermediate Layer 2 or Layer 3 network,
or a combination of one direct physical link and one or more distributed links. The AP uses one link for
booting, configuration, and data transfer and uses the other link(s) as backups in case the active link fails. If the
AP has two direct physical links to one or more WSSs, the Power over Ethernet (PoE) load is shared across
both links. If the active data link fails, the other link provides uninterrupted power to the AP.
After changing its active link, the access point reboots and loads new configuration information to ensure proper config-
uration and security. Mobility Domain services are temporarily disrupted by the link change. Dual-homed connections
are not required but are recommended. See also bias.