Users Guide

Class-of-Service 1583
In the first line of the configuration below, the first integer after the min-
thresh keyword configures green-colored Congestion Enabled TCP packets in
CoS queues 0 and 1 that exceed the WRED threshold (13% or ~38 Kbytes)
to mark packets as Congestion Experienced. The first integer after the max-
thresh parameter configures the upper threshold for green-colored TCP
packets to the same value as the min-thresh threshold. This causes the switch
to mark all ECN-capable queued packets as Congestion Experienced when
the threshold is reached or exceeded. TCP packets without ECN capability
bits set are dropped according to the normal WRED processing when the
threshold is exceeded. Packets on other CoS queues are handled in the
standard manner, i.e., tail-dropped when insufficient buffer is available.
Yellow and red packet configuration (second and third threshold parameters)
is kept at the defaults, as no metering to reclassify packets from green to
yellow or red is present. The last threshold parameter configures non-TCP
packets in CoS queues 0 and 1 to be processed with the WRED defaults. The
ecn keyword enables ECN marking of ECN-capable packets on CoS queues 0
and 1. The weighting constant is set to 0 in the second line of the
configuration, as described in the DCTCP paper cited above. Finally, CoS
queues 0 and 1 are configured for WRED in the last line of the configuration.
console(config)#random-detect queue-parms 0 1 min-thresh 13 30 20
100 max-thresh 13 90 80 100 drop-prob-scale 100 10 10 10 ecn
console(config)#random-detect exponential-weighting-constant 0
console(config)#cos-queue random-detect 0 1