ATM QoS Policy Command Reference
708 Quality of Service Guide
Configuring PIR for traffic descriptor profiles for UBR and UBR with MIR service categories has no
impact on a traffic contract when a PVCC using that profile resides on an m4-atmoc12/3-sfp XMA or
MDA. On this XMA or MDA SAR ignores PIR (defacto treating each UBR as it would have a PIR of
max. line rate). The default pir value for UBR and UBR with MIR reflects this behavior.
When a traffic descriptor profile is used to define egress scheduling, the following describes how
traffic rates are used to derive scheduling weight:
1. UBR PVCCs (i.e., MIR = 0) are assigned weight value of 1
2. UBR with MIR PVCCs are assigned weight value in the inclusive range from 1 to 255 based
on the MIR rate.
3. rt-VBR and nrt-VBR PVCCs are assigned weight value in the inclusive range from 1 to 255
based on the SCR rate
4. CBR PVCCs are assigned weight value in the inclusive range from 1 to 255 based on the PIR
rate
The scheduling weight is derived from the traffic rate based on the following formula:
If traffic rate <= 32 Kbps, then weight = 1
If 32 Kbps < traffic rate < 8160 Kbps, then weight = floor (traffic rate / 32)
If traffic rate >= 8160 Kbps, then weight = 255
The configuration of weight unit (32 Kbps) is left for future releases.
Since the SAR operates in cells/second with 1 cell granularity, PIR and SCR values programmed need
to be converted to cells per second. When converting values to be used for scheduler, the result is
rounded up to the next cell when required by conversion.
When any of SIR, PIR, or MIR is greater than the physical maximum port/channel capacity for a given
PVCC, then the maximum physical port/channel capacity is used in BW accumulation and when
configuring the H/W for that PVCC.
Hardware- enforceable mbs is in the inclusive range from 3 to 256 000 cells. Any value outside of that
range will be accepted and rounded up/down to the minimum/maximum enforceable value.
The no form of the command restores traffic parameters to their defaults for a given service category.
By default ATM traffic parameters are listed in Table 55 in kbps.
UBR with MIR N/A Y (must be
>= MIR
N/A Y (non-
zero MIR
specified)
N/A
Table 54: Traffic Descriptor Parameter Support by Service Category (Continued)
Service Category SIR PIR MBS MIR CDVT
To Next Page
Loading...
