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Configuring System Information 249
Configuring and Viewing sFlow Settings Using CLI Commands
For information about the CLI commands that perform this function, see the following chapter in the
CLI Reference Guide
:
• sFlow Commands.
sFlow Sampler Configuration
The sFlow Agent collects a statistical packet-based sampling of the switched flows and sends them to the
configured receivers. A data source configured to collect flow samples is called a sampler.
Packet Flow Sampling
The Packet Flow Sampling mechanism carried out by each sFlow instance ensures that any packet
observed at a Data Source has an equal chance of being sampled, irrespective of the Packet Flow(s) to
which it belongs.
Packet Flow Sampling is accomplished as follows:
• When a packet arrives on an interface, the Network Device makes a filtering decision to determine
whether the packet should be dropped.
• If the packet is not filtered (dropped), a destination interface is assigned by the switching/routing
function.
• At this point, a decision is made on whether or not to sample the packet. The mechanism involves a
counter that is decremented with each packet. When the counter reaches zero, a sample is taken.
When a sample is taken, the counter that indicates how many packets to skip before taking the next
sample is reset. The value of the counter is set to a random integer where the sequence of random
integers used over time is the Sampling Rate.
To access the sFlow Sampler Configuration page, click System > sFlow > Sampler Configuration in
the navigation tree.