DGS-6604
m
police
CLI Reference Guide
489
Later it is realized that a two rate police should be applied to class-movie traffic
and a two rate police (police cir command) is added. The newer police cir
command will overwrite the previous police command setting.
Specifying Multiple Actions
The police command allows to specify actions for different policing result. When
specifying multiple policing actions, contradictory actions, such as violate-action
transmit and exceed-action drop, cannot be specified.
Using the Police
Command with
the Traffic
Policing Feature
The Traffic Policing feature works with a token bucket algorithm. Two types of
token bucket algorithms are available: a one-token bucket algorithm and a two-
token bucket algorithm. A single-token bucket system is used when the violate-
action option is not specified, and a two-token bucket system is used when the
violate-action option is specified.
The following are explanations of how the token bucket algorithms work.
Token Bucket Algorithm with One Token Bucket
The one-token bucket algorithm is used when the violate-action option is not
specified in the police command CLI. The conform bucket is initially set to the full
size (the full size is the number of bytes specified as the normal burst size).
When a packet of a given size (for example, "B" bytes) arrives at specific time
(time "T"), the following actions occur:
“Tokens are updated in the conform bucket. If the previous arrival of the packet
was at T1 and the current time is T, the bucket is updated with (T - T1) worth of
bits based on the token arrival rate. The token arrival rate is calculated as
follows: (time between packets (which is equal to T - T1) * policer rate)/8 bytes.
The policer rate here is average rate (BPS).
"If the number of bytes in the conform bucket is greater than or equal to the
packet size, the packet conforms and the conform action is taken on the packet.
If the packet conforms, B bytes are removed from the conform bucket and the
conform action is completed for the packet.
"If the number of bytes in the conform bucket (minus the packet size to be
limited) is fewer than B, the exceed action is taken.
Token Bucket Algorithm with Two Token Buckets
The two-token bucket algorithm is used when the violate-action option is
specified in the police command. The conform bucket is initially full (the full size
Switch(config)# policy-map police-map1
Switch(config-pmap)# class class-movie
Switch(config-pmap-c)# police cir 8000 pir 1000 exceed-action drop violate-
action drop
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
