Juniper EX9200 Features Manual page 135

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NOTE: Before you apply a firewall filter that performs multifield classification
and also a policer to the same logical interface and for the same traffic
direction, make sure that you consider the order of policer and firewall filter
operations.
As an example, consider the following scenario:
You configure a firewall filter that performs multifield classification (acts
on matched packets by setting the forwarding class, the PLP, or both)
based on the packet's existing forwarding class or PLP. You apply the
firewall filter at the input of a logical interface.
You also configure a single-rate two-color policer that acts on a red traffic
flow by re-marking (setting the forwarding class, the PLP, or both) rather
than discarding those packets. You apply the policer as an interface policer
at the input of the same logical interface to which you apply the firewall
filter.
Because of the order of policer and firewall operations, the input policer is
executed before the input firewall filter. This means that the multifield
classification specified by the firewall filter is performed on input packets
that have already been re-marked once by policing actions. Consequently,
any input packet that matches the conditions specified in a firewall filter term
is then subject to a second re-marking according to the
loss-priority nonterminating actions also specified in that term.
"Firewall Filter Nonterminating Actions" in the Routing Policies, Firewall Filters, and Traffic
Policers Feature Guide
Order of Policer and Firewall Filter Operations on page 11
Two-Color Policer Configuration Overview on page 49
Multifield Classification Requirements and Restrictions on page 118
Multifield Classification Limitations on M Series Routers on page 119
Example: Configuring Multifield Classification on page 121
The Junos OS CoS Components Used to Manage Congestion and Control Service Levels
Understanding How Behavior Aggregate Classifiers Prioritize Trusted Traffic
Understanding How Forwarding Classes Assign Classes to Output Queues
Default Forwarding Classes
Managing Congestion Using RED Drop Profiles and Packet Loss Priorities
Chapter 11: Multifield Classification
or
forwarding-class
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