Guidelines for Applying Traffic Policers

The following general guidelines pertain to applying traffic policers:

• Only one type of policer can be applied to the input or output of the same physical or logical interface. For example, you are not allowed to apply a policer and a hierarchical policer in the same direction at the same logical interface.

• Chaining of policers—that is, applying policers to both a port and the logical interfaces of that port—is not allowed.

• A maximum of 64 policers is supported per physical or logical interface, provided no behavior aggregate (BA) classification—traffic classification based on CoS values in the packet headers—is applied to the logical interface.

• The policer should be independent of BA classification. Without BA classification, all traffic on an interface is treated either as expedited forwarding (EF) or non-EF, based on the configuration. With BA classification, a physical or logical interface can support up to 64 policers. The interface might be a physical interface or logical interface.

• With BA classification, the miscellaneous traffic (the traffic not matching any of the BA classification DSCP/EXP bits) is policed as non-EF traffic. No separate policers are installed for this traffic.

• Policers can be applied to unicast packets only. For information about configuring a filter for flooded traffic, see Applying Forwarding Table Filters.