Alcatel-Lucent 7950 SR, System Management Manual

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Security
7950 SR OS System Management Guide Page 41
DCP Policer Resource Management
The policer instances are a limited h/w resource on a given forwarding plane. DCP policers
(static, dynamic, local-monitor) are consumed from the overall forwarding plane policer
resources (from the ingress resources if ingress and egress are partitioned). Each per-protocol
policer instantiated reduces the number of FP child policers available for other purposes.
When DCP is configured with dynamic enforcement, then the operator must set aside a pool
of policers that can be instantiated as dynamic enforcement policers. The number of policers
reserved for this function are configurable per card/fp. The policers in this pool are not
available for other purposes (normal SLA enforcement).
Static enforcement policers and local monitoring policers use policers from the normal/global
policer pool on the card/fp.Once a static policer is configured in a DCP policy and it is
referenced by a protocol in the policy, then this policer will be instantiated for each object
(SAP or network interface) that is created and references the policy. If there is no policer free
on the associated card/fp, then the object will be blocked from being created. Similarly for
local monitors: once a local monitoring policer is configured and referenced by a protocol,
then this policer will be instantiated for each object that is created and references the policy.
If there is no policer free, then the object will be blocked from being created.
Dynamic enforcement policers are allocated as needed (when the local monitor detects non-
conformance) from the reserved dynamic-enforcement-policer-pool.
When a DCP policy is applied to an object on a LAG, then a set of policers is allocated on each
forwarding plane (on each line card that contains a member of the LAG). The LAG mode is
ignored and the policers are always shared by all ports in the LAG on that forwarding plane on
the SAP/interface. In other words, with link-mode lag a set of DCP policers are not allocated
per port in the LAG on the SAP.
In order to support large scale operation of DCP, and also to avoid overload conditions, a
polling process is used to monitor state changes in the policers. This means there can be a
delay between when an event occurs in the data plane and when the relevant state change or
event notification occurs towards an operator, but in the meantime the policers are still
operating and protecting the control plane.