ZyXEL P-663HN-51 User Guide - Page 55

WAN, WAN

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Chapter 5 WAN Setup 5.2.1.1 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. 5.2.1.2 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 realtime or non realtime connections. The realtime VBR 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 realtime VBR 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 non realtime VBR 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 non realtime VBR connection would be non-time sensitive data file transfers. 5.2.1.3 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. 5.3 WAN Click Advanced Setup > WAN to open the following screen. This screen displays your ZyXEL Device's WAN Internet access settings. You can also edit those settings and add more settings. The screen differs by the encapsulation. P-663HN-51 User's Guide 55

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Chapter 5 WAN Setup
P-663HN-51 User’s Guide
55
5.2.1.1
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.
5.2.1.2
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
realtime or non realtime
connections.
The realtime VBR 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 realtime VBR 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 non realtime VBR 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 non realtime VBR connection would be non-time
sensitive data file transfers.
5.2.1.3
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.
5.3
WAN
Click
Advanced Setup > WAN
to open the following screen.
This screen displays
your ZyXEL Device’s WAN Internet access settings. You can also edit those
settings and add more settings. The screen differs by the encapsulation.