Chapter 5 Broadband
ADSL Series User’s Guide
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congestion, which is important for transmission of real time data such as audio and video
connections.
Peak Cell Rate (PCR) is the maximum rate at which the sender can send cells. This parameter may
be lower (but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a
maximum speed of 832Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed
because it is dependent on the line speed.
Sustained Cell Rate (SCR) is the mean cell rate of each bursty traffic source. It specifies the
maximum average rate at which cells can be sent over the virtual connection. SCR may not be
greater than the PCR.
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 27
Example of Traffic Shaping
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.
Содержание P-660HN-F1
Страница 2: ...Videos ADSL Series User s Guide 2 Videos File Sharing Video Example 55 QoS Video Example 76...
Страница 6: ...Document Conventions ADSL Series User s Guide 6 Server Firewall Router Switch...
Страница 8: ...Safety Warnings ADSL Series User s Guide 8...
Страница 10: ...Contents Overview ADSL Series User s Guide 10...
Страница 19: ...19 PART I User s Guide...
Страница 20: ...20...
Страница 26: ...Chapter 1 Introduction ADSL Series User s Guide 26...
Страница 40: ...Chapter 2 Introducing the Web Configurator ADSL Series User s Guide 40...
Страница 80: ...Chapter 3 Tutorials ADSL Series User s Guide 80...
Страница 81: ...81 PART II Technical Reference...
Страница 82: ...82...
Страница 130: ...Chapter 6 Wireless ADSL Series User s Guide 130...
Страница 160: ...Chapter 8 Routing ADSL Series User s Guide 160...
Страница 164: ...Chapter 9 DNS Route ADSL Series User s Guide 164...
Страница 182: ...Chapter 11 Network Address Translation NAT ADSL Series User s Guide 182...
Страница 190: ...Chapter 13 Firewall ADSL Series User s Guide 190...
Страница 202: ...Chapter 15 Certificates ADSL Series User s Guide 202...
Страница 222: ...Chapter 16 VPN ADSL Series User s Guide 222...
Страница 226: ...Chapter 17 System Monitor ADSL Series User s Guide 226...
Страница 228: ...Chapter 18 User Account ADSL Series User s Guide 228...
Страница 242: ...Chapter 24 Backup Restore ADSL Series User s Guide 242...
Страница 246: ...Chapter 25 Diagnostic ADSL Series User s Guide 246...
Страница 254: ...Chapter 26 Troubleshooting ADSL Series User s Guide 254...
Страница 262: ...Chapter 27 Product Specifications ADSL Series User s Guide 262...
Страница 302: ...Appendix B Setting Up Your Computer s IP Address ADSL Series User s Guide 302...
Страница 310: ...Appendix C Pop up Windows Java Script and Java Permissions ADSL Series User s Guide 310...
Страница 334: ...Appendix E Common Services ADSL Series User s Guide 334...
Страница 355: ...Appendix F Open Software Announcements ADSL Series User s Guide 355...
Страница 356: ...Appendix F Open Software Announcements ADSL Series User s Guide 356...
Страница 360: ...Appendix G Legal Information ADSL Series User s Guide 360...