Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 924)

894 Multi-Service IronWare Switching Configuration Guide
53-1003036-02
Configuring and enabling sFlow
23
Brocade(config)# sflow destination 10.10.10.1
This command specifies a collector with IP address 10.10.10.1, listening for sFlow data on UDP
port 6343.
Syntax: [no] sflow destination ip-addr [dest-udp-port]
The ip-addr variable specifies the collector’s IP address.
The dest-udp-port variable specifies the UDP port on which the sFlow collector will be listening for
exported sFlow data. The default port number is 6343.
The sampled sFlow data sent to the collectors includes an agent_address field. This field identifies
the device that sent the data. Refer to
“Source address” .
Changing the polling interval
The polling interval defines how often sFlow byte and packet counter data for a port are sent to the
sFlow collectors.
The default polling interval is 20 seconds. You can change the interval to a value from 1 to any
higher value. The interval value applies to all interfaces on which sFlow is enabled. If you set the
polling interval to 0, counter data sampling is disabled.
To change the polling interval, enter a command such as the following at the global CONFIG level of
the CLI.
Brocade(config)# sflow polling-interval 30
Syntax: [no] sflow polling-interval secs
The secs variable specifies the interval and can be from 1 to any higher value. The default is 20
seconds. If you specify 0, counter data sampling is disabled.
Changing the sampling rate
The sampling rate is the average ratio of the number of packets received on an sFlow-enabled port
to the number of flow samples taken from those packets. By default, all sFlow-enabled ports use
the default sampling rate, which is 2048. With a sampling rate of 2048, on average, one in every
2048 packets forwarded on an interface is sampled.
You can change the default (global) sampling rate. You also can change the rate on an individual
port, overriding the default sampling rate.
NOTE
sFlow uses CPU resources to send sFlow samples to the collector. If you set a low sampling value on
a high rate interface (for example 10 GbE), the Interface module CPU utilization can become high.
Configuration considerations
The sampling rate is a fraction in the form 1/N, meaning that, on average, one out of every N
packets will be sampled. The sflow sample command at the global level or port level specifies N,
the denominator of the fraction. A higher denominator means a lower sampling rate because fewer
packets are sampled. Likewise, a lower number for the denominator means a higher sampling rate
because more packets are sampled. For example, if you change the denominator from 2,000 to
512, the sampling rate increases because four times as many packets will be sampled.