In asynchronous transfer mode (ATM), a class of traffic that requires access to time slots at a rate that can vary significantly from time to time. Real-time compressed voice and video and time-sensitive bursty data traffic are examples of VBR traffic. ATM also defines constant bit rate (CBR), non real-time Variable Bit Rate (nrt-VBR), non real-time Variable Bit Rate (nrt-VBR), real-time Variable Bit Rate (rt-VBR), and unspecified bit rate (UBR) traffic classes See also ABR, ATM, CBR, compression, nrt-VBR, real-time, rt-VBR, time slot, and UBR.
(2) (Variable Bit Rate) A channel that alters its transmission speed based on changing conditions.
(3) (Variable Bit Rate) A service level in an ATM network. Real-time VBR (rt-VBR) provides minimal delays for interactive voice and video. Non-real-time VBR (nrt-VBR) is used for bursty business transactions. See ATM.
(4) (Volume Boot Record) See boot sector.