WRED drops packets
selectively based on
any specified criteria, such
as CoS, DSCP, EXP, discard-class, or precedence
. WRED uses
to determine how to treat different types of traffic.
Configure WRED using the
random-detect command and different CoS, DSCP,
EXP, and discard-class values. The value can be range or a list of values that
are valid for that field. You can also use minimum and maximum queue thresholds
to determine the dropping point.
When a packet arrives, the
following actions occur:
queue size is less than the minimum queue threshold, the
arriving packet is queued.
queue size is between the minimum queue threshold for that
type of traffic and the maximum threshold for the interface, the packet is
either dropped or queued, depending on the packet drop probability for that
type of traffic.
queue size is greater than the maximum threshold, the packet
When configuring the
command, you must configure one of the following commands:
The Cisco ASR 9000 Series
ATM SPA supports only time-based WRED thresholds. Therefore, if you try to
configure the WRED threshold using the
random-detect default command with bytes or packet as the
threshold units, the "Unsupported WRED unit on ATM interface" error occurs.
Only two minimum and maximum thresholds (each with different
match criteria) can be configured per class.