Configuration Guide User guide

498 BigIron RX Series Configuration Guide
53-1002484-04
Configuring packet drop priority using WRED
18
Syntax: [no] qos queue-type <queue-number> wred drop-precedence <policing-status>
drop-probability-max
<p-max%>
The <queue-number> variable is the number of the forwarding queue that you want to configure
drop-precedence for. There are four forwarding queues on device. They are numbered 0 to 3 with
zero as the lowest priority queue and three the highest.
The <policing-status> variable indicates the traffic policing status for which you want to configure
drop-precedence.
The <p-max%> variable defines the maximum drop probability in when the queue size is at the
value configured for max-avg-q-size. This value is expressed as a percentage.
Configuring the maximum instantaneous queue size
You can set the maximum size to which a queue is allowed to grow. Packets that cause the queue
to grow beyond this setting are unconditionally dropped. To set the maximum instantaneous queue
size for queues with a queue type of 1 to 32000, use the following command.
BigIron RX(config)#qos queue-type 1 max-queue-size 32
Syntax: [no] qos queue-type <queue-number> max-queue-size <max-queue>
The <queue-type> variable is the number of the forwarding queue type that you want to configure
the instantaneous-queue-size parameter for. There are eight forwarding queue types on device
Routers. They are numbered 0 to 3.
The <max-queue> variable is the maximum size to which a queue is allowed to grow. It is defined in
Kbytes. The default values are shown in Table 104.
Setting the minimum and maximum average queue size
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.
BigIron RX(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.
BigIron RX(config)#qos queue-type 1 wred drop-precedence 0 min-avg-queue-size 64
Syntax: [no] qos queue-type <queue-type> wred drop-precedence <drop-precedence-value>
min-avg-queue-size <min-size>
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 BigIron RX Routers. They are
numbered 0 to 3.
The <drop-precedence-value> variable for the drop-precedence parameter is the TOS/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.