Hi Marcos,
The bandwidth share command is used to assign the weight for each queue; it controls how many packets each queue can forward in every interval. That is related to the amount of traffic you expect from each class. The mls qos queue-set output 2 buffers command is to configure the queue size for each queue; it controls how many packets each queue can hold. The mls qos queue-set output 2 threshold command controls when one particular queue starts drop packets.
There is no formula to calculate buffer size, but there is some general guidelines you can follow.
1,Set the threshold percentages levels higher than 100, so no packets are dropped before reserved buffer is full.
2, Avoid increase the “reserved” buffer for a given tx queue, because that will decrease common buffer pool.
3,Consider increasing the thresholds and the maximum before modifying the buffers and reserved buffer.
4, Modify the buffer size will affect all interfaces using same queue-set; so, you can consider use different queue-set for ports have different traffic pattern.
Based on the guidelines, you can use the following as the starting point, and adjust the value from there.
mls qos queue-set output 2 buffers 10 25 10 55
mls qos queue-set output 2 threshold 1 150 300 100 400
mls qos queue-set output 2 threshold 2 150 300 50 400
mls qos queue-set output 2 threshold 3 150 300 50 400
mls qos queue-set output 2 threshold 4 200 300 100 400
HTH,
Lei Tian
