Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 925)

Multi-Service IronWare Switching Configuration Guide 895
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Configuring and enabling sFlow
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NOTE
It is recommended that you do not change the denominator to a value lower than the default.
Sampling requires CPU resources. Using a low denominator for the sampling rate can cause high
CPU utilization.
Changing the global rate
If you change the global sampling rate, the change is applied to all sFlow-enabled ports except
those ports on which you have already explicitly set a sampling rate. For example, if you enable
sFlow on ports 1/1, 1/2, and 5/1 and you configure the sampling rate on port 1/1 but leave the
other two ports using the default rate, then changing the global sampling rate would apply to ports
1/2 and 5/1 but not port 1/1. sFlow uses the sampling rate you explicitly configured on the
individual port even if you globally changed the sampling rate for the other ports.
Sampling rate for new ports
When you enable sFlow on a port, the port's sampling rate is set to the global default sampling rate.
This also applies to ports on which you disable and then re-enable sFlow. The port retains the
sampling rate it had when you disabled sFlow forwarding on the port, unless the sflow sampling
rate is removed or moved to default rate.
Sflow sampling on Brocade NetIron CES and Brocade NetIron CER devices
NOTE
Sflow samples outbound traffic if the sflow enabled port is monitored by a mirror port.
On Brocade NetIron CES and Brocade NetIron CER devices, if mirrored Sflow packets are received
in the LP CPU there is no option to distinguish them from regular Sflow packets.
Changing the default sampling rate
NOTE
The NetIron CES and NetIron CER supports sflow sampling rate configuration per port basis.
The Brocade MLXe, NetIron MLX, and NetIron XMR supports sflow sampling rate configuration per
packet processer basis.
To change the default (global) sampling rate, enter a command such as the following at the global
CONFIG level of the CLI.
Brocade(config)# sflow sample 2048
Syntax: [no] sflow sample num
The num variable specifies the average number of packets from which each sample will be taken.
The sampling rate you configure is the actual sampling rate. You can enter a value from 512
through 2147483648. The default is 2048.
Changing the sampling rate on a port
You can configure an individual port to use a different sampling rate than the global default
sampling rate. This is useful in cases where ports have different bandwidths. For example, if you
are using sFlow on 10/100 ports and Gigabit Ethernet ports, you may want to configure the Gigabit
Ethernet ports to use a higher sampling rate (gathering fewer samples per number of packets) than
the 10/100 ports.