A
AAA
Authentication,
authorization, and accounting. A system in IP-based networking to control which computer
resources specific users can access and to keep track of the activity of specific users over
the network.
ABR
Area border router. In
OSPF, an ABR has interfaces in
multiple areas, and it is responsible for exchanging summary advertisements with other
ABRs.
ACL
Access Control List. A
mechanism for filtering packets at the hardware level. Packets can be classified by
characteristics such as the source or destination MAC, IP addresses, IP type, or QoS queue.
Once classified, the packets can be forwarded, counted, queued, or dropped.
ACMI
Asynchronous Chassis
Management Interface.
ad-hoc mode
An 802.11 networking
framework in which devices or stations communicate directly with each other, without the use
of an access point (AP).
AES
Advanced Encryption Standard. AES is an algorithm for encryption that
works at multiple network layers simultaneously. As a block cipher, AES encrypts data in
fixed-size blocks of 128 bits; AES is also a privacy transform for IPSec and Internet Key
Exchange (IKE). Created by the National Institute of Standards and Technology (NIST), the
standard has a variable key length—it can specify a 128-bit key (the default), a 192-bit
key, or a 256-bit key.
For the WPA2/802.11i implementation of AES, a 128-bit key length is
used. AES encryption includes four stages that make up one round. Each round is then
iterated 10, 12, or 14 times depending upon the bit-key size. For the WPA2/802.11i
implementation of AES, each round is iterated 10 times.
AES-CCMP
Advanced Encryption Standard - Counter-Mode/CBC-MAC Protocol. CCM is a
new mode of operation for a block cipher that enables a single key to be used for both
encryption and authentication. The two underlying modes employed in CCM include Counter mode
(CTR) that achieves data encryption and Cipher Block Chaining Message Authentication Code
(CBC-MAC) to provide data integrity.
alternate port
In
RSTP, the alternate port supplies an alternate path to the root
bridge and the root port.
AP (access
point)
In wireless technology,
access points are LAN transceivers or "base stations" that can connect to the regular wired
network and forward and receive the radio signals that transmit wireless data.
area
In
OSPF, an area is a logical set of segments
connected by routers. The topology within an area is hidden from the rest of the
autonomous system (AS).
ARP
Address Resolution
Protocol. ARP 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 traffic can be transmitted.
AS
Autonomous
system. In
OSPF, an AS is a connected
segment of a network topology that consists of a collection of subnetworks (with hosts
attached) interconnected by a set of routes. The subnetworks and the routers are expected to
be under the control of a single administration. Within an AS, routers may use one or more
interior routing protocols and sometimes several sets of metrics. An AS is expected to present
to other autonomous systems an appearance of a coherent interior routing plan and a consistent
picture of the destinations reachable through the AS. An AS is identified by a unique 16-bit
number.
ASBR
Autonomous
system border router. In
OSPF, an ASBR
acts as a gateway between OSPF and other routing protocols or other autonomous
systems.
association
A connection between a
wireless device and an access point.
ATM
Asynchronous
transmission mode. 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.
autobind
In
STP, autobind (when enabled) automatically
adds or removes ports from the STPD. If ports are added to the carrier VLAN, the member ports
of the VLAN are automatically added to the STPD. If ports are removed from the carrier VLAN,
those ports are also removed from the STPD.
autonegotiation
As set forth in IEEE
802.3u, autonegotation allows each port on the switch—in partnership with its link partner—to
select the highest speed between 10 Mbps and 100 Mbps and the best duplex mode.