Multipoint Shared Queuing - Alcatel-Lucent 7450 Quality Of Service Manual

Overview

Multipoint Shared Queuing

Multipoint shared queuing is supported to minimize the number of multipoint queues created
for ingress VPLS, IES or VPRN SAPs or ingress subscriber SLA profiles. Normally, ingress
multipoint packets are handled by multipoint queues created for each SAP or subscriber SLA
profile instance. In some instances, the number of SAPs or SLA profile instances are
sufficient for the in use multipoint queues to represent many thousands of queues on an
ingress forwarding plane. If multipoint shared queuing is enabled for the SAPs or SLA profile
instances on the forwarding plane, the multipoint queues are not created. Instead, the ingress
multipoint packets are handled by the unicast queue mapped to the forwarding class of the
multipoint packet.
Functionally, multipoint shared queuing is a superset of shared queuing. With shared queuing
on a SAP or SLA profile instance, only unicast packets are processed twice, once for the
initial service level queuing and a second time for switch fabric destination queuing. Shared
queuing does not affect multipoint packet handling. Multipoint packet handling in normal
(service queuing) is the same as shared queuing. When multipoint shared queuing is enabled,
shared queuing for unicast packets is automatically enabled.
Ingress Queuing Modes of Operation
Three modes of ingress SAP queuing are supported for multipoint services (IES, VPLS and
VPRN); service, shared, and multipoint shared. The same ingress queuing options are
available for IES and VPLS subscriber SLA profile instance queuing.
Ingress Service Queuing
Normal or service queuing is the default mode of operation for SAP ingress queuing. Service
queuing preserves ingress forwarding bandwidth by allowing a service queue defined in an
ingress SAP QoS policy to be represented by a group of hardware queues. A hardware queue
is created for each switch fabric destination to which the logical service queue must forward
packets. For a VPLS SAP with two ingress unicast service queues, two hardware queues are
used for each destination forwarding engine the VPLS SAP is forwarding to. If three switch
fabric destinations are involved, six queues are allocated (2 unicast service queues multiplied
by 3 destination forwarding complexes equals six hardware queues).
unicast hardware queue expansion. Service multipoint queues in the ingress SAP QoS policy
are not expanded to multiple hardware queues, each service multipoint queue defined on the
SAP equates to a single hardware queue to the switch fabric.
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Figure 36 demonstrates
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