Reference Guide

Glossary
ABR
In OSPF, an Area Border Router has interfaces in multiple areas, and it is responsible for exchanging
summary advertisements with other ABRs.
ACL
An Access Control List is a mechanism for filtering packets at the hardware level. Packets can be
classified by characteristics such as the source or destination MAC, IP address, IP type, or QoS queue.
Once classified, the packets can be forwarded, counted, queued, or dropped.
ad hoc mode
An 802.11 networking framework in which devices or stations communicate directly with each other,
without the use of an AP.
ARP
Address Resolution Protocol is part of the TCP/IP suite used to dynamically associate a device's physical
address (MAC address) with its logical address (IP address). The system broadcasts an ARP request,
containing the IP address, and the device with that IP address sends back its MAC address so that trac
can be transmitted.
ATM
Asynchronous Transmission Mode is a start/stop transmission in which each character is preceded by a
start signal and followed by one or more stop signals. A variable time interval can exist between
characters. ATM is the preferred technology for the transfer of images.
BGP
Border Gateway Protocol is a router protocol in the IP suite designed to exchange network reachability
information with BGP systems in other autonomous systems. You use a fully meshed configuration with
BGP.
BGP provides routing updates that include a network number, a list of ASs that the routing information
passed through, and a list of other path attributes. BGP works with cost metrics to choose the best
available path; it sends updated router information only when one host has detected a change, and only
the aected part of the routing table is sent.
BGP communicates within one AS using Interior BGP (IBGP) because BGP does not work well with IGP.
Thus the routers inside the AS maintain two routing tables: one for the IGP and one for IBGP. BGP uses
exterior BGP (EBGP) between dierent autonomous systems.
BSS
Basic Service Set is a wireless topology consisting of one access point connected to a wired network
and a set of wireless devices. Also called an infrastructure network. See also IBSS (Independent Basic
Service Set).
CHAP
Challenge-Handshake Authentication Protocol is one of the two main authentication protocols used to
verify a user's name and password for PPP Internet connections. CHAP is more secure because it
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