Alcatel-Lucent 7450 - Page 644

Overview
644 Quality of Service Guide
When the first SAP or SLA profile instance is configured for shared queuing on an ingress
forwarding plane, the system allocates eight hardware queues per available destination
forwarding plane, one queue per forwarding class. Twenty-four hardware queues are also
allocated for multipoint shared traffic, but that is discussed in the following section. The
shared queue parameters that define the relative operation of the forwarding class queues are
derived from the Shared Queue policy defined in the QoS CLI node. Figure 37 demonstrates
shared unicast queuing. SAP or SLA profile instance multipoint queuing is not affected by
enabling shared queuing. Multipoint queues are still created as defined in the ingress SAP
QoS policy and ingress multipoint packets only traverse the ingress forwarding plane a single
time.
Enabling shared queuing may affect ingress performance due to double packet processing
through the service and shared queues.
Figure 37: Unicast Service Queuing With Shared Queuing Enabled
Dest n
Queue
PIR set to minimize jitter, Second
Pass discards Out-of-Contract
Ingress
???
for RT Traffic
Fig_23
Service
Queue
Service
Queue
Service
Queue
Dest C
Queue
Dest D
Queue
Dest E
Queue
Dest A
Queue
Dest B
Queue
Ingress
Forwarding Plane
First Pass
Queue Decisions
Based on QoS
Policy Service
Queue Mapping
of FC and
Forwarding Type
Ingress
Forwarding Plane
Second Pass
Queue Decision
Based on
FC and SF
Destination