Packets satisfying the match
criteria for a class accumulate in the queue reserved for the class until they
are serviced. The
queue-limit
command is used to define the maximum threshold for a
class. When the maximum threshold is reached, enqueued packets to the class
queue result in tail drop (packet drop).
The
queue-limit
value uses the guaranteed service rate (GSR) of the queue as the reference
value for the
queue_bandwidth . If the class has bandwidth
percent associated with it, the
queue-limit is
set to a proportion of the bandwidth reserved for that class.
If the GSR for a queue is
zero, use the following to compute the default
queue-limit :
-
1 percent of the interface
bandwidth for queues in a nonhierarchical policy.
-
1 percent of parent maximum
reference rate for hierarchical policy.
The parent maximum reference rate is the minimum of parent shape,
policer maximum rate, and the interface bandwidth.
The default
queue-limit is
set as follows:
default queue limit (in bytes) = (<200|100|10> ms *
queue_bandwidth kbps) / 8
Note |
You can configure the queue limit in all the priority classes.
|
Restrictions
-
When configuring the
queue-limit
command in a class, you must configure one of the following commands:
priority ,
shape average ,
bandwidth , or
bandwidth
remaining , except for the default class.
-
On the Cisco CRS Series
Modular Services Card 140G (CRS-MSC-140G), a police action
must be configured in the
same class as the priority action. A class configuration that includes a
priority action but no police action is not valid. Such a configuration is
rejected.