Users Guide

Layer 2 Switching Commands 760
• queue-id—The internal class of service queue (range 0-6). The queue-id is
not the same as the CoS value received in incoming packets. Use the show
classofservice dot1p-mapping command to display the CoS value to
internal CoS queue mapping.
• min-thresh—The minimum threshold at which to begin dropping, based
on the configured maximum drop probability for each color and for non-
TCP packets. Range 0 to 250. At or below the minimum threshold, no
packets are dropped. The range between the minimum and maximum
thresholds is divided equally into eight increasing levels of drop probability.
• max-thresh—The maximum threshold to end dropping at the configured
maximum drop probability for each color and for non-TCP packets. Range
0 to 250. Above the maximum threshold, 100% of matching packets are
dropped.
• drop-prob-scale—The maximum drop probability. Range 0-100. This is the
drop probability for a packet when the maximum threshold is reached.
Above the maximum threshold, 100% of matching packets are dropped.
• ecn—Enables ECN marking for the selected CoS queues. Packets marked
as ECN capable are not dropped when selected for discard by WRED.
NOTE: The ecn parameter is not supported on the N1500 series switch.
Default Configuration
The table below shows the default green, yellow, and red TCP and non-TCP
minimum/maximum drop thresholds and the green, yellow and red TCP and
non-TCP drop probabilities. The thresholds for each color and CoS queue are
configured independently and may overlap. By default, WRED is not enabled
for any CoS queue and ECN is not enabled for any CoS queue.
Queue ID WRED Minimum
Threshold
WRED Maximum
Threshold
WRED Drop
Probability Scale
ECN Enabled
0 40/30/20/100 100/ 90/ 80/100 10/ 10/ 10/ 10 No
1 40/30/20/100 100/ 90/ 80/100 10/ 10/ 10/ 10 No
2 40/30/20/100 100/ 90/ 80/100 10/ 10/ 10/ 10 No
3 40/30/20/100 100/ 90/ 80/100 10/ 10/ 10/ 10 No