Page 36 7750 SR OS Services Guide
Figure 3: Multipoint Queue Behavior with Shared Queuing Enabled
Ingress Multipoint Shared Queuing
Ingress multipoint shared queuing is a variation to the unicast shared queuing defined in Ingress
Shared Queuing on page 34. Ingress unicast service queues are mapped one-for-one with 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 predominate scenario where
multipoint shared queuing may be required is with subscriber managed QoS environments using a
OSSG227
Multicast
Queue
Multipoint Service Queue is
Represented by a Single
Hardware Queue (Single Pass)
Service
Queue
Unicast Service Queue is Represented by a Single Hardware Queue.
But Dual Pass Through the Forwarding Plane.
Hardware
Dest Queue
Second Pass
Switch Fabric
Unicast
SFEgress
MDA 1
SFEgress
MDA 2
SFEgress
MDA 3
SFEgress
MDA n
Multicast
Hardware
Dest Queue
Hardware
Dest Queue
Hardware
Queue
Hardware
Dest Queue
Hardware
Dest Queue
To Next Page
Loading...
