then forwards the frame out all the ports.
American National Standards Institute (ANSI)
The organization that publishes standards for communications, programming languages, and
networking.
ANDingThe process of comparing the bits of an IP address with the bits in a subnet mask to determine how a
packet will be handled.
anycast address
An address used in ATM for shared multiple−end systems. An anycast address allows a frame to be
sent to specific groups of hosts.
Application layer
The layer of the OSI model that provides support for end users and for application programs using
network resources.
Application−Specific Integrated Circuit (ASIC)
A feature of many LAN controllers. ASICs are internal to the switch. They work in conjunction with
the internal processor to make Layer 2 forwarding decisions. However, they lack the ability to make
flexible software−implemented forwarding decisions. Their ability to perform small tasks quickly and
inexpensively makes them a key in the switching process. ASICs used in Cisco switches and routers
are the Phoenix, FE, LMA, PFPA, SAMBA, SAGE, SAINT, and CEF.
Asymmetric Digital Subscriber Line (ADSL)
A service that transmits digital voice and data over existing (analog) phone lines.
Asynchronous Transfer Mode (ATM)
An international standard originally developed by the International Telecommunications Union
Telecommunication Standardization Sector (ITU−T), used in high−speed transmission media such as
E3, Synchronous Optical Network (SONET), and T3 for cell relay. It can be used in multiple service
types such as voice, video, or data, and it’s sent in fixed−length, 53−byte cells. ATM has become
common on today’s corporate networks. It guarantees throughput and minimizes delay. It can provide
scalable speeds up to multiple gigabits per second.
Asynchronous Transmission Synchronization (ATS)
A process used in serial data transfer in which a start bit and a stop bit are added so the receiving
station knows when a particular bit has been transferred. Also known as bit synchronization.
ATM Adaptation layer (AAL)
The ATM layer that adapts data to the ATM 48−byte payload. There are a number of adaptations to
this layer, such as AAL1, AAL2, AAL3/4, and AAL5. AAL5 is by far the most common in today’s
networks. AAL5 defines how data from a node on the network such as a PC or server handles ATM
cells. It is also used by Cisco Catalyst switches with LANE to perform segmentation and reassembly
of ATM frames into cells and cells into frames.
ATM System Processor (ASP)
A Cisco ATM cell−switching processing card, located on the Cisco Catalyst 5500 chassis or slot 2 on
the LS1010 chassis.
attachment unit interface (AUI)
IEEE 802.3 specification used between a Multistation Access Unit (MAU) and a NIC.
attachment unit interface (AUI) connector
A 15−pin D−type connector sometimes used with Ethernet connections.
attenuation
The loss of signal that is experienced as data is transmitted across network media.
Automated Packet Recognition and Translation (APaRT)
A FDDI line module feature found on Cisco Catalyst 2820 and 5000 series switches that allows for
the automatic detection of frame types with translational bridging. It uses the CAM table to get the
frame−type information for all end nodes.
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