Configuring and applying a policer – Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) User Manual
Page 991
Quality of Service (QoS) Introduction
Software Reference for x310 Series Switches
C613-50046-01 REV A
AlliedWare Plus
TM
Operating System - Version 5.4.4C
38.19
When data enters the port at the CIR, the bucket fills at the same rate as the incoming
data, thus the token count in bucket C remains constant. Similarly, if data enters the port
at the PIR, then the token count in bucket P remains constant. You can specify the CIR and
the PIR by using the
command. The function of this command is
explained in the section
“Configuring and Applying a Policer” on page 38.19
.
A surge of data exceeding the CIR will begin to empty bucket C. If bucket C empties to a
point where it has insufficient tokens to match to an incoming data packet, then the data
packet will be marked yellow. The data will now be measured against the level in bucket P
and tokens will be removed from this bucket to match the incoming data. If the incoming
data rate drops to less than the CIR then the data will continue to be marked yellow until
the level in bucket C has had a chance to fill, whereupon it will be marked green.
If the incoming data is greater than the PIR, then bucket P begins to empty. If bucket P
empties to a point where it has insufficient tokens to match to an incoming data packet,
then the data packet will be marked red. In this situation no tokens are removed from
either bucket.
Note that although the data is metered per byte, the color marking process is applied per
packet. This means that if there were only sufficient tokens available to match part of a
packet, then the whole packet would be marked red. Then, depending on the action
parameter of the
command, the whole packet will be either
dropped, or marked and forwarded. In either situation, the red marked packet will leave
the bucket counts unchanged.
Configuring and Applying a Policer
The previous section showed how the policer works and how to select either the single
rate or twin rate action. To apply a policy to class-maps:
■
Select your policy-map and class-map from the command prompt, then enter either
the
command
whilst selecting the appropriate command parameters.
This will apply the command to the selected class-map. By running this command several
times, each for a different class-map, you can apply separate meter settings to each class-
map.