ATM QoS Traffic Descriptor Profiles
382
Quality of Service Guide
3HE 11014 AAAC TQZZA Edition: 01
8.1.1.3 ATM Policing
The policing option, when enabled, applies only to ingress traffic. Similarly, the
shaping option, if enabled, applies only to egress traffic. For example, if a traffic
descriptor has both policing and shaping enabled, the policing option is enforced for
the ingress traffic, while the shaping option is enforced for the egress traffic. The
following ATM service category conformance definitions are supported:
• P0_1 – CBR
• P0_1 and S0_1 – VBR.1
• P0_1 and S0 – VBR.2
• P0_1 and S0_Tag – VBR.3
P represents the peak rate, S represents the sustained rate, 0 or 1 represents the
CLP value to which policing is applied if the cell is non-conforming, and Tag indicates
that the CLP value has changed from 0 to 1. For example:
• P0_1 — means that policing is applied to non-conforming peak rate cells with
CLP values of 0 or 1
• P0_1 and S0_Tag — means that policing is applied to non-conforming peak rate
cells with CLP values of 0 or 1 and policing is applied to non-conforming
sustained rate cells with a CLP value of 0 with the action to change the CLP
value to 1
8.1.1.4 Shaping
ATM layer egress shaping is supported for CBR, rt-VBR, and nrt-VBR VCs. A CBR
VC is shaped to a single leaky bucket with the parameter PIR from the traffic
descriptor. An rt-VBR VC or an nrt-VBR VC is shaped to two leaky buckets with
parameters PIR and SIR, BT from the traffic descriptor, where BT is the Burst
Tolerance and is a function of the MBS parameters configured by the user. The traffic
rates and shaping parameter that are configured in the sap-egress QoS policy are
not used at ATM SAPs.
In order to enforce the Service Level Agreement, ATM layer ingress policing is
supported at ingress, so no shaping is needed. At ingress, after optional policing is
applied, packet level queue-based soft-policing is supported per the service ingress
QoS policy applied to the ATM SAP.
Note: Shaping to the specified traffic descriptor in the ATM traffic descriptor profile is always
enabled for CBR and rt-VBR VCs.
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