12-14
Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 12 Sharing Bandwidth Fairly During Congestion
Configuring Fair Bandwidth Sharing During Congestion
Configuration Example for Configuring a Class Policy and Dropping Packets Using WRED
Example 12-3
creates the class map named
class1
and defines the match criteria used to determine if
packets belong to the class. The policy map named
policy1
contains the class characteristics for class1.
Because the class1 configuration specifies the
random-detect
command, the policy map uses WRED
packet drop to drop packets. The service policy for policy1 is applied to the PVC range 1/32 to 1/81 for
outbound packets.
Example 12-3 Configuring a Class Policy and Dropping Packets Using WRED
Router(config)#
class-map class1
Router(config-cmap)#
match input-interface Ethernet0/1
Router(config-cmap)#
exit
Router(config)#
policy-map policy1
Router(config-pmap)#
class class1
Router(config-pmap-c)#
bandwidth 1000
Router(config-pmap-c)#
random-detect
Router(config-pmap-c)#
exit
Router(config-pmap)#
exit
Router(config)#
interface atm 1/0/0
Router(config-if)#
atm pxf queuing
Router(config-if)#
interface atm 1/0/0.1 point-to-point
Router(config-subif)#
range pvc 1/32 1/81
Router(config-subif-range-vc)#
service-policy output policy1
!
Step 5
Router(config-pmap-c)#
random-detect
exponential-weighting-constant
exponent
or
Router(config-pmap-c)#
random-detect
precedence
precedence min-threshold
max-threshold mark-prob-denominator
Configures the exponential weight factor used in calculating the
average queue length.
exponent
is a number from 1 to 16 used in the average queue size
calculation.
Configures WRED parameters for packets with a specific IP
precedence. Repeat this command for each precedence.
precedence
is the IP precedence number. Valid values are from 0
to 7.
min-threshold
is the minimum average queue length, expressed in
number of packets. Valid values are from 1 to 4096. When the
average queue length reaches the minimum threshold, WRED
randomly drops some packets with the specified IP precedence.
max-threshold
is the maximum average queue length, expressed
in number of packets. Valid values are from the value of the
min-threshold to 4096. When the average queue length exceeds
the maximum threshold, WRED drops all packets with the
specified IP precedence.
mark-prob-denominator
is the denominator for the fraction of
packets dropped when the average queue depth is at the maximum
threshold. For example, if the denominator is 512, 1 out of every
512 packets is dropped when the average queue is at the maximum
threshold. Valid values are from 1 to 65536. The default is 10 (1
out of every 10 packets is dropped at the maximum threshold).
Command
Purpose