Ingress CFHP Queuing
7950 XRS Quality of Service Guide
Page 575
Post-CFHP Queuing and Scheduling
Although CFHP enforces aggregate rate limiting while maintaining sensitivity to strict priority and
fair access to bandwidth within a priority, CFHP output packets still require queuing and
scheduling to provide access to the switch fabric or to an egress port.
Ingress CFHP Queuing
At ingress, CFHP output traffic is automatically mapped to a unicast or multipoint queue in order
to reach the proper switch fabric destinations. In order to manage this automatic queuing function,
a shared queue policy policer-output-queues. For modifying parameters in this shared-queue
policy, refer to
Shared-Queue QoS Policy Command Reference on page 429
.
The unicast queues in the policy are automatically created on each destination switch fabric tap
and ingress CFHP unicast packets automatically map to one of the queues based on forwarding
class and destination tap. The multipoint queues within the policy are created on the multicast
paths; 16 multicast paths are supported by default with 28 on 7950 XRS systems and 7750 12-e
systems, with the latter having setting “tools perform the system set-fabric-speed fabric-speed-b.”
The multicast paths represent an available multicast switch fabric path - the number of each being
controlled using the command:
CLI Syntax:
configure mcast-management bandwidth-policy
policy-name
t2-
paths secondary-path
number-paths
number-of-paths
[dual-sfm
number-of-paths
]
For ingress CFHP multicast packets (Broadcast, Unknown unicast or Multicast—referred to as
BUM traffic), the system maintains a conversation hash table per forwarding class and populates
the table forwarding class hash result entry with the one of the multicast paths. Best-effort traffic
uses the secondary paths, and expedited traffic uses the primary paths.When a BUM packet is
output by ingress CFHP, a conversation hash is performed and used along with the packets
forwarding class to pick a hash table entry in order to derive the multicast path to be used. Each
table entry maintains a bandwidth counter that is used to monitor the aggregate traffic per
multicast path. This can be optimized by enabling IMPM on any forwarding complex which
allows the system to redistribute this traffic across the IMPM paths on all forwarding complexes to
achieve a more even capacity distribution. Be aware that enabling IMPM will cause routed and
VPLS (IGMP and PIM) snooped IP multicast groups to be managed by IMPM.
Any discards performed in the ingress shared queues will be reflected in the ingress child policer's
discard counters and reported statistics assuming a discard counter capable stat-mode is
configured for the child policer.
Summary of Contents for 7950
Page 12: ...Page 12 7950 XRS Quality of Service Guide List of Figures ...
Page 16: ...Preface Page 16 7950 XRS Quality of Service Guide ...
Page 82: ...Editing QoS Policies Page 82 7950 XRS Quality of Service Guide ...
Page 90: ...Applying Network Queue Policies Page 90 7950 XRS Quality of Service Guide ...
Page 96: ...Editing QoS Policies Page 96 7950 XRS Quality of Service Guide ...
Page 98: ...Command Hierarchies Page 98 7950 XRS Quality of Service Guide ...
Page 108: ...Command Hierarchies Page 108 7950 XRS Quality of Service Guide ...
Page 156: ...Basic Configurations Page 156 7950 XRS Quality of Service Guide exit exit ...
Page 164: ...Queue Depth Monitoring Page 164 7950 XRS Quality of Service Guide ...
Page 304: ...Service Queue QoS Policy Commands Page 304 7950 XRS Quality of Service Guide ...
Page 368: ...Command Hierarchies Page 368 7950 XRS Quality of Service Guide ...
Page 430: ...Configuration Commands Page 430 7950 XRS Quality of Service Guide ...
Page 532: ...Editing QoS Policies Page 532 7950 XRS Quality of Service Guide ...
Page 552: ...Editing Advanced Policies Page 552 7950 XRS Quality of Service Guide ...
Page 600: ...Command Hierarchies Page 600 7950 XRS Quality of Service Guide ...
Page 602: ...QoS Commands Page 602 7950 XRS Quality of Service Guide ...
Page 610: ...Standards and Protocols Page 610 7950 XRS Quality of Service Guide ...
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