configure sflow ports sample-rate
ExtremeWare XOS 11.5 supports only the Summit X450 family of switches and the BlackDiamond 8800 series switch.
ExtremeWare XOS 11.5 Command Reference Guide
599
configure sflow ports sample-rate
configure sflow ports <portlist> sample-rate <number>
Description
Configures the sFlow per-port sampling rate.
Syntax Description
Default
The default number is 8192, unless modified by the
configure sflow sample-rate
command.
Usage Guidelines
This command configures the sampling rate on a particular set of ports, and overrides the system-wide
value set in the
configure sflow sample-rate
command. The rate is rounded off to the next power
of two, so if 400 is specified, the sample rate is configured as 512. The valid range is 1 to 536870912.
BlackDiamond 10808 Switch Only.
At the hardware level, the sampling rate for all ports on a slot is the
same. Ports that are configured for fewer samples than other ports on the slot (the
number
parameter is
larger) still take the same amount of samples at the hardware level as ports configured for more
samples. The excess samples are discarded. This mechanism is displayed in the
show sflow
{configuration}
command as the sub-sampling factor. For example, if one port is configured for a
sample rate of 1024, and a second port on the same slot is configured for a sample rate of 4096, the
second port’s hardware actually samples one out of 1024 packets, but only saves the information for one
out of four of those samples. In this example, the sub-sampling factor is four.
Configuring a lower number for the sample rate means that more samples will be taken, increasing the
load on the switch. Do not configure the sample rate to a number lower than the default unless you are
sure that the traffic rate on the source is low.
If the rate of samples going to the CPU exceeds a limit, set with the
configure sflow max-cpu-
sample-limit
command, then the sample rate number will be doubled, effectively reducing the rate by
one-half. Under those conditions, the configured rate may not be the actual rate of sampling. The output
of the
show sflow configuration
command will display the configured and actual rate of sampling.
Summit X450 Family of Switches and BlackDiamond 8800 a-Series and e-Series Modules.
All ports on the
switch or same I/O module are sampled individually.
Example
The following command sets the sample rate for the ports 4:6 to 4:10 to one packet out of every 16384:
configure sflow ports 4:6-4:10 sample-rate 16384
portlist
Specifies a list of ports.
number
Specifies the fraction (1/number) of packets to be sampled.
