Multipoint Shared Queuing - Alcatel-Lucent 7750 SR OS Service Manual

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).
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.
When multiple hardware queues represent a single logical service queue, the system automatically
monitors the offered load and forwarding rate of each hardware queue. Based on the monitored
state of each hardware queue, the system imposes an individual CIR and PIR rate for each queue
that provides an overall aggregate CIR and PIR reflective of what is provisioned on the service
queue.
7750 SR OS Services Guide
Figure 1 demonstrates unicast hardware
Services
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