Mellanox MLNX-OS User Manual for SX1018HP Ethernet Managed Blade Switch

Rev 2.10
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Figure 16: sFlow Functionality Overview
5.12.1 Flow Samples
The sFlow agent samples the data path packet based.
Truncation and sampling rate are the two parameters that
influence the flow samples. In case of
congestion the flow samples can be truncated to a predefined size before it is being assigned to
the CPU. The truncation can be set to any value between 64 to 256 bytes with the default being
128 bytes. Furthermore, the sampling rate may also be adjust as required.
5.12.2 Statistical Samples
The sFlow agent samples interface counters time based. Polling interval is configurable to any
value between 5-3600 seconds with the default being 20 seconds.
The following statistics are gathered by the CPU:
Table 44 - List of Statistical Counters
Counter Description
Total packets The number of packets that pass through sFlow-enabled ports.
Number of flow samples The number of packets that are captured by the sampling mecha-
ni
sm.
Number of statistic samples The number of statistical samples.
Number of discarded samples The number of samples that were discarded.
Number of datagrams The number of datagrams that were sent to the
collector.
5.12.3 sFlow Datagrams
The sFlow datagrams contain flow samples and statistical samples.
The sFlow mechanism uses IP protocol, therefore if the packet length is more than the i
nterface
MTU, it becomes fragmented by the IP stack. The MTU may also be set manually to anything in
the range of 200-9216 bytes. The default is 1400 bytes.