Appendix A Reference Information
ATM Service Categories in the PSAX System
A-8
255-700-585
PacketStar
®
PSAX 3-Port DS3/E3 ATM Protection Module User Guide
, Issue 1
Release 10.0.0
ATM Service Categories in the PSAX System
ATM Service Category Descriptions
The PSAX system support of defined ATM quality of service (QoS) categories
is described in Table A-4.
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-5. 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-4. 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.
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