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Glossary

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VTP pruning

VLAN Trunk Protocol is used to communicate VLAN infor-

mation between switches in the same VTP domain. VTP pruning stops
VLAN update information from being sent down trunked links if the
updates are not needed.

WAN

wide area network: A designation used to connect LANs together

across a DCE (data communications equipment) network. Typically, a
WAN is a leased line or dial-up connection across a PSTN network. Examples
of WAN protocols include Frame Relay, PPP, ISDN, and HDLC.

weighted fair queuing

Default queuing method on serial links on all

Cisco routers.

wildcard

Used with access-list, supernetting, and OSPF configurations.

Wildcards are designations used to identify a range of subnets.

windowing

Flow-control method used with TCP at the Transport layer of

the OSI model.

WinSock

Windows Socket Interface: A software interface that makes it

possible for an assortment of applications to use and share an Internet con-
nection. The WinSock software consists of a Dynamic Link Library (DLL)
with supporting programs such as a dialer program that initiates the connection.

workgroup switching

A switching method that supplies high-speed

(100Mbps) transparent bridging between Ethernet networks as well as high-
speed translational bridging between Ethernet and CDDI or FDDI.

X.25

An ITU-T packet-relay standard that defines communication

between DTE and DCE network devices. X.25 uses a reliable Data Link
layer protocol called LAPB. X.25 also uses PLP at the Network layer. X.25
has mostly been replaced by Frame Relay.

X.25 protocol

First packet-switching network, but now mostly used in

Europe. Replaced in the U.S. by Frame Relay.

XTAG

A locally significant numerical value assigned by the MLS-SE to

each MLS-RP in the Layer 2 network. See also: MLS-SE, MLS-RP.

ZIP

Zone Information Protocol: A Session layer protocol used by Apple-

Talk to map network numbers to zone names. NBP uses ZIP in the determi-
nation of networks containing nodes that belong to a zone. See also: ZIP
storm and zone.

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