PurposeCommand
Collects the system up time for the first or
last packet in the flow.
collect timestamp sys-uptime {first | last}
Example:
switch(config-flow-record)# collect timestamp
sys-uptime last
Collects the TCP transport layer flags for the
packets in the flow.
collect transport tcp flags
Example:
switch(config-flow-record)# collect transport tcp
flags
Collects the IP version for the flow.collect ip version
Example:
switch(config-flow-record)# collect ip version
Sampled NetFlow
Cisco NX-OS supports sampled NetFlow. This feature samples incoming packets on an interface. The packets
sampled then qualify to create flows. Sampled NetFlow reduces the amount of export data sent to the collector
by limiting the number of packets that create flows and the number of flows. It is essential when flows are
created on a line card or external device, instead of on the forwarding engine.
The sampling mode supported is M out of N (M:N), where M packets are selected randomly out of every N
packets for sampling, and only those packets can create flows. The lowest possible sampling rate on the Cisco
Nexus 6000 series is 1:64K packets. The following table shows the different packet rates for different port
types when the sampling rate is set to 1:64K packets:
Number of packets using a 1:64K sampled packet ratePort Speed
231 Gigabit
23010 Gigabit
92040 Gigabit
The values in the above table apply to 64 Byte sized packets. The values are different for different size of
packets.
Note
Guidelines and Limitations for NetFlow
NetFlow has the following configuration guidelines and limitations:
•
In sampler mode using M:N, N must be a power of 2. For example 1024, 2048, or 4096.
•
You must configure a source interface. If you do not configure a source interface, the flow exporter will
remain in a disabled state.
Cisco Nexus 5600 Series NX-OS System Management Configuration Guide, Release 7.x
OL-31641-01 265
Configuring NetFlow
Sampled NetFlow
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