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Appendix A Reference Information
ATM Service Categories in the PSAX System
A-10
255-700-714R11.0
PacketStar
®
PSAX 1-Port Channelized OC-3/STM-1 CES Module User Guide
, Issue 1
Release 11.0.0
The PSAX system support of defined ATM quality of service (QoS) categories
is described in Table A-7.
Priority of ATM Service Categories in the PSAX System
The attributes of the categories of service supported by the PSAX system soft-
ware are identified in Table A-8. The service examples in this table are
intended simply as illustrations; you should choose your service category
based on your network applications supported by the PSAX system. The flex-
ibility of the PSAX system allows you to tailor the system based on the
required service applications by selecting the appropriate connection configu-
ration selection field value.
Table A-7. PSAX System-Supported Quality of Service Categories
ATM Service Category
Description
Constant Bit Rate (CBR) This service offers consistent delay predictability. CBR is used for applica-
tions such as circuit emulation, voice, and video.
Real Time Variable Bit
Rate (VBR-rt)
This service offers low delay variance, but requires access to a variable
amount of network bandwidth. VBR-rt is used for applications such as
packet video and voice.
Non-Real Time Variable
Bit Rate (VBR-nrt)
This service allows delay variance between the delivery of cells. VBR-nrt
is used for data applications that have potentially bursty traffic character-
istics.
Guaranteed Frame Rate
(GFR)
This service allows delay variance and offers a minimum cell rate guaran-
tee. When used with frame-based data encapsulated in AAL5 PDUs, it
provides frame-based cell discard. GFR is used for frame relay or ethernet
over ATM.
Unspecified Bit Rate
(UBR)
This service allows for best-effort transport by the network. Cells are
transported by the network whenever bandwidth is available and the
user presents traffic.
Table A-8. Mapping ATM Service Categories to PSAX System Priority Levels
ATM Service Category
Connection
Configuration
Field Value
AQueMan Priority
(Legacy
Implementation)
ATM Forum Traffic
Management 4.1
Priority (Current
Implementation)
Service Examples
Constant Bit Rate (CBR)
CBR1
Highest
Highest
911 calls
CBR2
Lower than
CBR1
Preferred customers
CBR3
Lower than
CBR2
Standard
CBR4
Lower than
CBR3
Cellular
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