An ATM layer service category for which the limiting ATM layer transfer characteristics provided by the network may change subsequent to connection establishment. A flow control mechanism is specified which supports several types of feedback to control the source rate in response to changing ATM layer transfer characteristics.
verage it ate refers to the average amount of data transferred per second. This is commonly referred to for digital music or video. An mp3 file, for example, that has an average bit rate of 128 kbit/s transfers, on average, 128,000 bits every second. It can have higher bit rate and lower bit rate parts, and the average bit rate is obtained by dividing the sum of the bit rate of each sample by the number of samples. Bit rate is not the only measure of audio/video quality, as some formats such as wma and Vorbis produce higher sound quality than the standard mp3 format at the same bit rate. [more...
One of five ATM Forum-defined service categories. In this service type, the network makes the best effort to pass the maximum number of cells but does not guarantee cell delivery. Supports variable bit rate data traffic with flow control, a minimum guaranteed data transmission rate and specified performance parameters. In exchange for regulating user traffic flow, the network offers minimal cell loss of accepted traffic. Traffic parameters are PCR and MCR. QoS parameters are CLR and CER.
ABR - Average Bitrate A compromise between CBR and VBR, ABR allows the user to set an average bitrate (and in turn a total number of bits allocated to the song). The encoder then operates on the same principle as VBR by using a higher bitrate to encode more complex sections of a song, only with extra bits ¡°loaned¡± by the lower bitrate values. Most traditional of the three methods is CBR encoding. This uses a constant user-defined bitrate value (e.g. 128kbps) throughout the song. This means that all sections get equal encoding and sizing. At the beginning of the MP3 scene, nearly every MP3 floating around was 128kbps CBR. Many still are. However, when people start to use MP3 as their main music source, one looks at higher encoding qualities and better encoding techniques...
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.
See 1) Auto Baud Rate; 2) Available Bit Rate.
Available Bit Rate. Quality of Service class defined by the ATM Forum for ATM networks where a timing relationship is not required between sending and receiving stations.
Available Bit Rate - an ATM Bearer Service Class for adaptive applications to be given, dynamically, a fair share of the network.
AVAILABLE BIT RATE. An ATM service category that is used for data traffic. The ABR categorycan tolerate delays. For each data transmission, ABR negotiates a rangeof acceptable bandwidths and an acceptable cell loss ratio (the number ofcells that can be lost in any transmission).
available bit rate. A class of service defined for ATM connections by the ATM Forum. Devices using ABR are guaranteed no more than a certain rate of throughput. This rate dynamically changes and the current value is relayed to the sending device by resource management (RM) cells.
Available Bit Rate. One of the two best effort ATM service types (the other one is UBR), where the network makes no absolute guarantee of cell delivery; however, it guarantees a minimum bit rate for user transmission. An effort is also made to keep cell loss as low as possible.
Available Bit Rate. Quality of Service (QOS) used for connections that are not delay or time sensitive - for example, connections that carry spontaneous or bursty data.
One of the ATM service classes. ABR supports VBR data traffic with average and peak traffic parameters (for example, LAN interconnection and internetworking services, LAN emulation, critical data transfer that requires service guarantees). Remote procedure calls, distributed file services, and computer process swapping and paging are examples of applications that would be appropriate for ABR.
Available Bit Rate. An ATM traffic type that optimizes the transmission resources available during data transmission. Configuring a PVC or SVC for ABR means that if the network conditions change (for example, if congestion occurs, the source can adapt its transmission rate accordingly - based on feedback from the network and destination - while remaining within the limits of the three pre-configured parameters: Peak Rate, Minimum Rate, and Initial Rate).
Available Bit Rate. An ATM layer service where the limiting ATM-layer transfer characteristics provided by the network may change subsequent to the connection established.
A service class for ATM in which the peak cell rate is dictated by the network.