3Com WL-603 - Manual (Page 85)

Internet Settings 83
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VBR (variable bit rate): QoS class defined by the ATM Forum for
ATM networks. VBR is subdivided into a real time (RT) class and
non-real time (NRT) class. VBR (RT) is used for connections in which
there is a fixed timing relationship between samples. VBR (NRT) is
used for connections in which there is no fixed timing relationship
between samples, but that still need a guaranteed QoS. Compare
with ABR, CBR, and UBR.
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UBR (unspecified bit rate): the UBR service class is intended for
delay-tolerant or non-real-time applications, for example, those
which do not require tightly constrained delay and delay variation,
such as traditional computer communications applications. The
UBR service may be considered as “best effort service”.
6 PCR/SCR/MBS: PCR (Peak Cell Rate), SCR (Sustainable Cell Rate) and MBS
(Maximum Burst Size) are configurable.
7 Click Apply.