3Com WL-542 - Manual (Page 51)

Internet Settings 49
PPPoA
PPP over ATM, this is a popular choice among European DSL providers. To
configure this page correctly, you should obtain the information on this
page from your ISP.
Figure 39 PPPoA Settings Screen
1 Select PPPoA from the Protocol drop-down menu.
2 Enter the VPI and VCI parameters provided to you by your ISP in the VPI
and VCI fields.
3 Select the encapsulation type (LLC or VC MUX) in the Encapsulation Type
field. This information is provided to you by your ISP.
4 Select the type of Quality of Service (CBR, UBR or VBR) in the QoS field.
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CBR (constant bit rate): the CBR service class is intended for
real-time applications, for example, those requiring tightly
constrained delay and delay variation, such as voice and video
applications. The consistent availability of a fixed quantity of
bandwidth is considered appropriate for CBR service.
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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".
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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