Nokia 7705 - 3.7.4 MC-MLPPP SAP Egress QoS Policies

QoS and QoS Policies
134
Quality of Service Guide
3HE 11014 AAAC TQZZA Edition: 01
3.7.4 MC-MLPPP SAP Egress QoS Policies
SAPs running MC-MLPPP have their own SAP egress QoS policies that differ from
standard policies. Unlike standard SAP policies, MC-MLPPP SAP egress policies do
not contain queue types, CIR, CIR adaptation rules, or dot1p re-marking.
Standard and MC-MLPPP SAP egress policies can never have the same policy ID
except when the policy ID is 1 (default). Standard SAP egress QoS policies cannot
be applied to SAPs running MC-MLPPP. Similarly, MC-MLPPP SAP egress QoS
policies cannot be applied to standard SAPs. The default policy can be applied to
both MC-MLPPP and other SAPs. It will remain the default policy regardless of SAP
type.
MC-MLPPP on the 7705 SAR supports scheduling based on multi-class
implementation. Instead of the standard profiled queue-type scheduling, an
MC-MLPPP encapsulated access port performs class-based traffic servicing.
The four MC-MLPPP classes are scheduled in a strict priority fashion, as shown in
Table 22.
For example, if a packet is sent to an MC-MLPPP class 3 queue and all other queues
are empty, the 7705 SAR fragments the packet according to the configured fragment
size and begins sending the fragments. If a new packet is sent to an MC-MLPPP
class 2 queue, the 7705 SAR finishes sending any fragments of the class 3 packet
that are on the wire, then holds back the remaining fragments in order to service the
higher-priority packet. The fragments of the first packet remain at the top of the class
3 queue. For packets of the same class, MC-MLPPP class queues operate on a
first-in, first-out basis.
Table 22 MC-MLPPP Class Priorities
MC-MLPPP Class Priority
0 Priority over all other classes
1 Priority over classes 2 and 3
2 Priority over class 3
3 No priority