Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.1P1 - Page 832
Configuring Specify Collectors, Changing the Polling Intervals, Back-Off Mechanism, Configuring
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Example of Viewing sFlow Configuration (Line Card) Dell#show sflow Stack-unit 1 Stack-unit 1 Samples rcvd from h/w :0 Total UDP packets exported :0 UDP packets exported via RPM :0 UDP packets dropped :36 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] ] | [maxdatagram-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. As a result of back-off, the actual sampling-rate of an interface may differ from its configured sampling rate. You can view the actual sampling-rate of the interface and the configured sample-rate by using the show sflow command. 832 sFlow
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