D-Link DGS-6600-48T Product Manual - Page 484

DGS-6604 m police 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. Switch(config)# policy-map police-map1 Switch(config-pmap)# class class-movie Switch(config-pmap-c)# police cir 8000 pir 1000 exceed-action drop violateaction drop Switch(config-pmap-c)# exit Switch(config-pmap)# exit Using the Police Command with the Traffic Policing Feature 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. 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 twotoken bucket algorithm. A single-token bucket system is used when the violateaction 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 CLI Reference Guide 474