Alcatel-Lucent 7450 Quality Of Service Manual page 645

Ethernet service switch; service router; extensible routing system

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Figure 38: Multipoint Queue Behavior with Shared Queuing Enabled

Multipoint Service Queue is

representated by a single

Hardware Queue (Single Pass)

Ingress Multipoint Shared Queuing

Ingress multipoint shared queuing is a variation to the unicast shared queuing defined in

Ingress Shared

hardware queues and unicast packets traverse the ingress forwarding plane twice. In addition

to the above, the multipoint queues defined in the ingress SAP QoS policy are not created.

Instead, multipoint packets (broadcast, multicast and unknown unicast destined) are treated

to the same dual pass ingress forwarding plane processing as unicast packets. In the first pass,

the forwarding plane uses the unicast queue mappings for each forwarding plane. The second

pass uses the multipoint shared queues to forward the packet to the switch fabric for special

replication to all egress forwarding planes that need to process the packet.

The benefit of defining multipoint shared queuing is the savings of the multipoint queues per

service. By using the unicast queues in the first pass and then the aggregate shared queues in

the second pass, per service multipoint queues are not required. The predominant scenario

where multipoint shared queuing may be required is with subscriber managed QoS

environments using a subscriber per SAP model. Usually, ingress multipoint traffic is

minimal per subscriber and the extra multipoint queues for each subscriber reduces the

Quality of Service Guide

Unicast Service Queue is

representated by a single

Hardware Queue But Dual Pass

through the Forwarding Plane

Queuing. Ingress unicast service queues are mapped one-for-one with

Shared-Queue QoS Policies

Switch Fabric