Definitions for teachers by teachers

ATM

by Sue Cooper

ATM (Asynchronous Transfer Mode) This standard packet-switching protocol for transmitting and receiving data uses uniform 53-byte cells. (Each cell has a 5-byte address header and 48 bytes of data.) These short, standardized cells can be processed through a digital ATM switch very  quickly, allowing for data transmission speeds surpassing 600 mbps. ATM  was designed to support multiple services, including voice, graphics, data, and full-motion video. It also allows telephone and cable TV companies to dynamically assign bandwidth to individual customers.

Other meanings:
1. Automatic Teller Machine
2. Adobe Type Manager
3. At The Moment  (in chat)

Sources:
http://coverage.cnet.com/Resources/Info/Glossary/Terms/atm.html
http://www.computeruser.com/resources/dictionary/

by Constanza Bacca & Pedro Willging

ATM-Asynchronous transfer mode is an advanced method of packet (data) switching(transfering) that provides high speed data transmission over local and wide area networks.  ATM can handle transmission of voice, data, fax, real-time video, CD quality audio, and imaging.  ATM can transfer data from 25 to 622 Mbps compared to Ethernet which can transfer a maximum of 100 Mbps.

"When purchasing ATM service, you generally have a choice of four different types of service:

Constant Bit Rate (CBR) specifies a fixed bit rate so that data is sent.
in a steady stream. This is analogous to a leased line. Variable Bit Rate (VBR) provides a specified throughput capacity but data is not sent evenly. This is a popular choice for voice and videoconferencing data.
Unspecified Bit Rate (UBR) does not guarantee any throughput levels. This is used for applications, such as file transfer, that can tolerate delays.
Available Bit Rate (ABR) provides a guaranteed minimum capacity but allows data to be bursted at higher capacities when the network is free."

*direct quote from Webopedia

Resource:  Webopedia

by Mike Sennert

ATM

ATM, short for Asynchronous Transfer Mode, like Ethernet, allows for transfer of data across the internet. It is able to transmit video, audio and computer data over the network without having any one type of data slow down the system more than any other type. It is capable of transferring more data than Ethernet, which relies on TCP/IP. However, TCP/IP breaks down transmissions into smaller units called "packets" which allows data to be broken down into smaller parts during transit only to come together again when it reaches its destination. ATM data travels as one whole unit, which makes it easier to track usage of various users but would slow down the system even more during times of peak usage. Because of its expense, Rolling Meadows High School does not use ATM on its network.

Links: ATM Tutorial, Info from 3com on Switching your network to ATM

by Pat Thornburn

ATM (Asynchronous Transfer Mode)- ATM is the "international standard for cell relay". It will allow voice, video, or data to be conveyed at fixed length cells of 53 bytes. These fixed length cells allow the processing of the information to occur in hardware., which reduces transit delays. ATM transfers the data in cells or packets (packets include the address and the data). These cells are small and create a fixed channel or communication path. ATM provides the standards of 25 Mbps and 155 Mbps transmission speeds which is faster than Ethernet. Therefore, it can take advantage of the high speed transmission media such as E3, SONET, and T3. ATM differs from TCP/IP because TCP/IP divides the messages into packets, and each packet may take a different route to get to the destination. However, ATM makes is easier by sending all the information over the same channel. This also make it easier to track and bill the information used in an ATM. The drawback to ATM occurs when there is a sudden surge of usage of ATM, and that may cause more problems since ATM has the set channel. ATM has four types of service available:

• Constant Bit Rate (CBR): This is like a leased line with a steady stream of data
• Variable Bit Rate (VBR): This has a specified throughput capacity for the data and the data is not sent evenly.
• Unspecified Bit Rate (UBR): This has no levels of transfer guaranteed.
• Available Bit Rate (ABR): This has a guaranteed minimum for the rate data is transferred, but if the network is free, the data will be sent faster.

by Kristin Zage

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