Cisco 6400 Einstellungsanleitung PDF herunterladen (Seite 175)

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Cisco 6400 Software Setup Guide

OL-1183-04

GLOSSARY

AAA

authentication, authorization, and accounting (pronounced "triple a").

AAL ATM adaptation layer. Service-dependent sublayer of the data link layer. The AAL accepts data from

different applications and presents it to the ATM layer in the form of 48-byte ATM payload segments.

AALs consist of two sublayers, CS and SAR. AALs differ on the basis of the source-destination timing

used, whether they use CBR or BVR, and whether they are used for connection-oriented or

connectionless mode data transfer. See AAL5.

AAL5 ATM adaptation layer 5. One of four AALs recommended by the ITU-T. AAL5 is used predominantly

for the transfer of packet-based traffic.

ABR

available bit rate. QoS class defined by the ATM Forum for ATM networks. ABR is used for

connections that do not require timing relationships between source and destination. ABR provides no

guarantees in terms of cell loss or delay, providing only best-effort service. Traffic sources adjust their

transmission rate in response to information they receive describing the status of the network and its

capability to successfully deliver data. Compare with CBR, UBR, and VBR.

ACR allowed cell rate. Parameter defined by the ATM Forum for ATM traffic management. ACR varies

between the MCR and the PCR, and is dynamically controlled using congestion control mechanisms.

address mask Bit combination used to describe which portion of an address refers to the network or subnet and which

part refers to the host.

ADM

add drop multiplexer. In an operations support system, a multiplexer that allows a signal to be added

into or dropped out of a Synchronous Optical Network (SONET) span.

ADSL asymmetric digital subscriber line. One type of DSL technology. ADSL is designed to deliver more

bandwidth downstream (from the central office to the customer site) than upstream. Downstream rates

range from 1.5 to 9 Mbps, while upstream bandwidth ranges from 16 to 640 kbps. ADSL transmissions

work at distances up to 18,000 feet (5488 meters) over a single copper twisted pair.

AFI authority and format identifier. Portion of an NSAP-format ATM address that identifies the type and

format of the IDI portion of an ATM address. See also IDI and NSAP.

AIS

alarm indication signal. In a T1 transmission, an all-ones signal transmitted in lieu of the normal signal

to maintain transmission continuity and to indicate to the receiving terminal that there is a transmission

fault that is located either at, or upstream from, the transmitting terminal.

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