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Maximum Burst Size (MBS) is the maximum number of cells that can be sent at the PCR. After MBS
is reached, cell rates fall below SCR until cell rate averages to the SCR again. At this time, more
cells (up to the MBS) can be sent at the PCR again.
If the PCR, SCR or MBS is set to the default of "0", the system will assign a maximum value that
correlates to your upstream line rate.
The following figure illustrates the relationship between PCR, SCR and MBS.
Figure 35
Example of Traffic Shaping
6.5.1 ATM Traffic Classes
These are the basic ATM traffic classes defined by the ATM Forum Traffic Management 4.0
Specification.
Constant Bit Rate (CBR)
Constant Bit Rate (CBR) provides fixed bandwidth that is always available even if no data is being
sent. CBR traffic is generally time-sensitive (doesn't tolerate delay). CBR is used for connections
that continuously require a specific amount of bandwidth. A PCR is specified and if traffic exceeds
this rate, cells may be dropped. Examples of connections that need CBR would be high-resolution
video and voice.
Variable Bit Rate (VBR)
The Variable Bit Rate (VBR) ATM traffic class is used with bursty connections. Connections that use
the Variable Bit Rate (VBR) traffic class can be grouped into real time (VBR-RT) or non-real time
(VBR-nRT) connections.
The VBR-RT (real-time Variable Bit Rate) type is used with bursty connections that require closely
controlled delay and delay variation. It also provides a fixed amount of bandwidth (a PCR is
specified) but is only available when data is being sent. An example of an VBR-RT connection would
be video conferencing. Video conferencing requires real-time data transfers and the bandwidth
requirement varies in proportion to the video image's changing dynamics.
The VBR-nRT (non real-time Variable Bit Rate) type is used with bursty connections that do not
require closely controlled delay and delay variation. It is commonly used for "bursty" traffic typical
on LANs. PCR and MBS define the burst levels, SCR defines the minimum level. An example of an
VBR-nRT connection would be non-time sensitive data file transfers.
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Страница 126: ...Chapter 8 Wireless LAN AMG1202 T10A User s Guide 126 ...
Страница 142: ...Chapter 10 Firewall AMG1202 T10A User s Guide 142 ...
Страница 148: ...Chapter 11 Filters AMG1202 T10A User s Guide 148 ...
Страница 152: ...Chapter 12 Static Route AMG1202 T10A User s Guide 152 ...
Страница 158: ...Chapter 13 802 1Q 1P AMG1202 T10A User s Guide 158 ...
Страница 166: ...Chapter 14 Quality of Service QoS AMG1202 T10A User s Guide 166 ...
Страница 202: ...Chapter 19 Logs AMG1202 T10A User s Guide 202 ...
Страница 223: ...Chapter 23 Product Specifications AMG1202 T10A User s Guide 223 ...
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Страница 264: ...Appendix C Pop up Windows JavaScripts and Java Permissions AMG1202 T10A User s Guide 264 ...
Страница 278: ...Appendix D Wireless LANs AMG1202 T10A User s Guide 278 ...
Страница 286: ...Appendix F Legal Information AMG1202 T10A User s Guide 286 ...
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