Quality of Service Guide QoS and QoS Policies
Edition: 01 3HE 11014 AAAC TQZZA 37
Figure 3 and Figure 4 illustrate per-SAP aggregate shapers for access ingress and
access egress, respectively. They indicate how shaped and unshaped SAPs are
treated.
H-QoS is not supported on the 4-port SAR-H Fast Ethernet module.
3.1.7.1 Shaped and Unshaped SAPs
Shaped SAPs have user-configured rate limits (PIR and CIR)—called the aggregate
rate limit—and must use 16-priority scheduling mode. Unshaped SAPs use default
rate limits (PIR is maximum and CIR is 0 kb/s) and can use 4-priority or 16-priority
scheduling mode.
Shaped 16-priority SAPs are configured with a PIR and a CIR using the
agg-rate-limit command in the config>service>service-type service-id>sap
context, where service-type is epipe, ipipe, ies, vprn, or vpls (including routed
VPLS). The PIR is set using the agg-rate variable and the CIR is set using the cir-rate
variable.
Unshaped 4-priority SAPs are considered unshaped by definition of the default PIR
and CIR values (PIR is maximum and CIR is 0 kb/s). Therefore, they do not require
any configuration other than to be set to 4-priority scheduling mode.
Unshaped 16-priority SAPs are created when 16-priority scheduling mode is
selected, when the default PIR is maximum and the default CIR is 0 kb/s, which are
same default settings of a 4-priority SAP. The main reason for preferring unshaped
SAPs using 16-priority scheduling over unshaped SAPs using 4-priority scheduling
is to have a coherent scheduler behavior (one scheduling model) across all SAPs.
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