Dell PowerConnect M6220 User's Guide - Page 251

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. Configuring System Information 249