Configuration Guide (Supporting R05.6.00) Manual

Multi-Service IronWare QoS and Traffic Management Configuration Guide 123
53-1003037-02
Configuring packet drop priority using WRED
4
The queue-type variable is the number of the forwarding queue type that you want to configure
drop-precedence for. There are eight forwarding queue types on Brocade devices. They are
numbered 0 to 7.
The drop-precedence-value variable for the drop-precedence parameter is the TOS or DSCP value
in the IPv4 or IPv6 packet header. It determines drop precedence on a scale from 0 - 3. Packets
than contain a DSCP value of 0 are least likely to be dropped and packets with a value of 3 are
most likely to be dropped. The default value is 0.
The p-max variable defines the maximum drop probability when the queue size is at the value
configured for max-avg-q-size. This value is expressed as a percentage. Use the % sign after you
type the drop-probability-max value. The default values are shown in Table 31.
Setting the minimum and maximum average queue size
Configuration Considerations
When setting the minimum and maximum average queue size, consider the following
• If a user enters a min-avg-queue-size that is equal to what is currently configured for the
max-avg-queue-size, then the min-avg-queue-size is decremented by 64. The
min-avg-queue-size is decremented by 64 because the value must be different from the
max-avg-queue-size that is currently configured. The following example is a warning message
that is displayed on the console.
Warning: The min-avg-queue-size is decreased to(min-avq-queue-size-64)as min and
max should be different to be effective.
• If a user enters a max-avg-queue-size that is equal to what is currently configured for the
min-avg-queue-size, then the max-avg-queue-size is incremented by 64. The
max-avg-queue-size is incremented by 64 because the value must be different from the
min-avg-queue-size that is currently configured. The following example is a warning message
that is displayed on the console.
Warning: The max-avg-queue-size is increased to(max-avq-queue-size+64)as min and
max should be different to be effective.
• If a user enters a min-avg-queue-size equal to the max-avg-queue-size, then the
max-avg-queue-size is incremented by 64. The max-avg-queue-size is incremented by 64
because the value must be different from the min-avg-queue-size The following example is a
warning message that is displayed on the console.
Warning: The max-avg-queue-size is increased to(max-avq-queue-size+64)as min and
max should be different to be effective.
However if a user enters a max-avg-queue-size and min-avg-queue-size equal to 32768, then the
min-avg-queue-size is decremented.
To set the maximum average queue size for queue type 1 and drop precedence 0 to the maximum
size of 32768 Kbytes, use the following command.
Brocade(config)#qos queue-type 1 wred drop-precedence 0 max-avg-queue-size 32768
Syntax: [no] qos queue-type queue-type wred drop-precedence drop-precedence-value
max-avg-queue-size max-size
To set the minimum average queue size to the maximum size of 16 Kbytes, use the following
command.