Brocade BigIron RX Series Configuration Guide - Manual (Page 577)

BigIron RX Series Configuration Guide 499
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Configuring packet drop priority using WRED
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The <min-size> variable is the average queue size below which all packets are accepted. Possible
values are 1 - 32768 KBytes. It must be set in multiples of 64K. The default values are shown in
Table 104 .
The <max-size> variable is the average queue size above which all packets are dropped. (1 -
32768) (KBytes) in multiples of 64K. The default values are shown in
Table 104 .
Setting the maximum packet size
To set the maximum drop probability for queue type 1 and drop precedence 0 when the queue size
reaches the Max-average-q-size value to 20% use the following command.
BigIron RX(config)#qos queue-type 1 wred drop-precedence 0 drop-probability-max
20%
Syntax: [no] qos queue-type <queue-type> wred drop-precedence <drop-precedence-value>
drop-probability-max <p-max%>
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.
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. The default values are
shown in
Table 104 .
Restoring to default WRED parameters
Table 104 describes all of the default values for each of the WRED parameters. If you change any
of the values from the default values, you can restore the defaults per queue type. To reset the
queue type 1 with default values for the WRED parameters, use the following command.
BigIron RX(config)#qos queue-type 1 wred default-params
Syntax: [no] qos queue-type <queue-number> default-params
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 BigIron RX Routers. They are numbered
0 to 3.
TABLE 104 WRED default settings
Queue
type Drop
precedence Minimum
average
queue size
(KByte) Maximum
average
queue size
(KByte) Maximum
packet size
(Byte) Maximum
drop
probability Maximum
instantaneous
queue size Average
weight
0 0 356 1024 16384 2% 1024 0.2%
1 304 1024 16384 4%
2 256 1024 16384 9%
3 204 1024 16384 10%
1 0 356 1024 16384 2% 1024 0.2%