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Glossary

acknowledgment

Verification sent from one network device to another

signifying that an event has occurred. May be abbreviated as ACK or Ack.
Contrast with: NAK.

accounting

One of the three components in AAA. Accounting provides

auditing and logging functionalities to the security model.

ACR

allowed cell rate: A designation defined by the ATM Forum for man-

aging ATM traffic. Dynamically controlled using congestion control mea-
sures, the ACR varies between the minimum cell rate (MCR) and the peak
cell rate (PCR). See also: MCR and PCR.

active monitor

The mechanism used to manage a Token Ring. The net-

work node with the highest MAC address on the ring becomes the active
monitor and is responsible for management tasks such as preventing loops
and ensuring that tokens are not lost.

address learning

Used with transparent bridges to learn the hardware

addresses of all devices on an internetwork. The switch then filters the net-
work with the known hardware (MAC) addresses.

address mapping

By translating network addresses from one format to

another, this methodology permits different protocols to operate
interchangeably.

address mask

A bit combination descriptor identifying which portion of

an address refers to the network or subnet and which part refers to the host.
Sometimes simply called the mask. See also: subnet mask.

address resolution

The process used for resolving differences between

computer addressing schemes. Address resolution typically defines a method
for tracing Network layer (Layer 3) addresses to Data Link layer (Layer 2)
addresses. See also: address mapping.

adjacency

The relationship made between defined neighboring routers

and end nodes, using a common media segment, to exchange routing
information.

administrative distance

A number between 0 and 225 that expresses the

value of trustworthiness of a routing information source. The lower the
number, the higher the integrity rating.

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