Configuring Specify Collectors; Changing The Polling Intervals; Back-Off Mechanism - Dell Z9000 Configuration Manual

Example of Viewing sFlow Configuration (Line Card)
Dell#show sflow stack-unit 1
stack-unit 1
Samples rcvd from h/w
Samples dropped for sub-sampling :69
Total UDP packets exported
UDP packets exported via RPM
UDP packets dropped

Configuring Specify Collectors

The sflow collector command allows identification of sFlow collectors to which sFlow datagrams are
forwarded.
You can specify up to two sFlow collectors. If you specify two collectors, the samples are sent to both.
• Identify sFlow collectors to which sFlow datagrams are forwarded.
CONFIGURATION mode
sflow collector ip-address agent-addr ip-address [number [max-datagram-size
number] ] | [max-datagram-size number ]
The default UDP port is 6343.
The default max-datagram-size is 1400.

Changing the Polling Intervals

The sflow polling-interval command configures the polling interval for an interface in the
maximum number of seconds between successive samples of counters sent to the collector.
This command changes the global default counter polling (20 seconds) interval. You can configure an
interface to use a different polling interval.
To configure the polling intervals globally (in CONFIGURATION mode) or by interface (in INTERFACE
mode), use the following command.
• Change the global default counter polling interval.
CONFIGURATION mode or INTERFACE mode
sflow polling-interval interval value
– interval value: in seconds.
The range is from 15 to 86400 seconds.
The default is 20 seconds.

Back-Off Mechanism

If the sampling rate for an interface is set to a very low value, the CPU can get overloaded with flow
samples under high-traffic conditions.
In such a scenario, a binary back-off mechanism gets triggered, which doubles the sampling-rate (halves
the number of samples per second) for all interfaces. The backoff mechanism continues to double the
sampling-rate until the CPU condition is cleared. This is as per sFlow version 5 draft. After the back-off
changes the sample-rate, you must manually change the sampling rate to the desired value.
sFlow
:165
:77
:77
:
749