Chapter 4 Broadband
46
eircom D1000 modem U
ser’s Guide
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.
Unspecified Bit Rate (UBR)
The Unspecified Bit Rate (UBR) ATM traffic class is for bursty data transfers. However, UBR doesn't
guarantee any bandwidth and only delivers traffic when the network has spare bandwidth. An
example application is background file transfer.
Содержание eircom D1000
Страница 2: ...Copyright 2013 ZyXEL Communications Corporation...
Страница 3: ......
Страница 12: ...10 eircom D1000 modem User s Guide...
Страница 13: ...PART I User s Guide 11...
Страница 14: ...12...
Страница 18: ...16 eircom D1000 modem User s Guide...
Страница 26: ...Chapter 2 Introducing the Web Configurator 24 eircom D1000 modem User s Guide...
Страница 27: ...PART II Technical Reference 25...
Страница 28: ...26...
Страница 78: ...76 eircom D1000 modem User s Guide Chapter 5 Wireless LAN...
Страница 110: ...10 8 eircom D1000 modem User s Guide Chapter 6 Home Networking...
Страница 120: ...Chapter 8 Quality of Service QoS 118 eircom D1000 modem User s Guide Figure 83 QoS Class Setup Add Edit...
Страница 126: ...Chapter 8 Quality of Service QoS 124 eircom D1000 modem User s Guide...
Страница 136: ...134 eircom D1000 modem User s Guide Chapter 9 Network Address Translation NAT...
Страница 148: ...146 eircom D1000 modem User s Guide Chapter 12 Filter...
Страница 168: ...Chapter 14 Parental Control 166 eircom D1000 modem User s Guide...
Страница 174: ...Chapter 15 Certificates 172 eircom D1000 modem User s Guide...
Страница 180: ...178 eircom D1000 modem User s Guide Chapter 17 Traffic Status...
Страница 182: ...180 eircom D1000 modem User s Guide Chapter 18 User Account...
Страница 184: ...182 eircom D1000 modem User s Guide Chapter 19 System Setting...
Страница 187: ...185 eircom D1000 modem User s Guide Chapter 20 Time Setting...
Страница 188: ...Chapter 20 Time Setting 186 eircom D1000 modem User s Guide...
Страница 196: ...Chapter 23 Backup Restore 194 eircom D1000 modem User s Guide...
Страница 210: ...Chapter 25 Diagnostic 208 eircom D1000 modem User s Guide...
Страница 216: ...214 eircom D1000 modem User s Guide Chapter 27 LED Descriptions...