Cfhp Ingress And Egress Use Cases - Alcatel-Lucent 7450 Quality Of Service Manual

CFHP Ingress and Egress Use Cases

While ingress CFHP seems a natural fit based on how policers are typically used in today's
networks, CFHP may also be used at egress. The reasons for utilizing egress CFHP may be
to provide a non-jitter or latency inducing aggregate SLA for multiple ingress flows or simply
to provide higher scale in the number of egress aggregate SLAs supported.
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 has been created or exists by default and is named
policer-output-queues. For modifying parameters in this shared-queue policy, refer to
Shared-Queue QoS Policy Command
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 IOM3-XP's 16/IMM or XMA multicast paths; 16 multicast paths are supported by default
with 28 on 7950 XRS systems and the 7750 SR 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:
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
Quality of Service Guide
Reference.
configure mcast-management bandwidth-policy policy-name
t2-paths secondary-path
number-paths number-of-paths [dual-sfm number-of-paths]
Class Fair Hierarchical Policing (CFHP)
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