sFlow Monitoring with PRTG

sFlow is a sampling technology for network monitoring invented by InMon. It works similarly to Cisco’s NetFlow and was first introduced by HPE in 2001. It stands for “sampled flow,” and uses statistical samples of data traffic to ensure scalability for interfaces with large amounts of data.

sFlow is designed to monitor network traffic with minimal impact on scarce resources. It does this by analyzing random samples of traffic (sFlow sampling) instead of capturing every packet. sFlow's default sampling rate is 8192, but we recommend adjusting it to suit your network's requirements. The lower the sampling rate, the lighter the load (and vice versa, of course).

sFlow consists of several key components that work together to provide scalable network traffic monitoring. These components include:

• sFlow agent: The sFlow agent is the software running on a network device (such as a switch, router, or server) that collects traffic samples and interface counters. It combines flow and counter samples into sFlow datagrams and sends them to the sFlow collector.
• sFlow collector: The sFlow collector is a centralized system or server that receives sFlow datagrams from one or more sFlow agents. It processes, stores, and analyzes the data, providing insights into network traffic patterns, performance, and security.

sFlow monitoring is a network monitoring technology used to capture and analyze traffic data in real-time. It operates by sampling packets flowing through network devices, such as switches and routers, to provide insights into network traffic patterns and performance. Unlike traditional methods that inspect every packet, sFlow uses statistical sampling to efficiently monitor network traffic without overwhelming the monitoring system.

It collects key information about network traffic, including source and destination IP addresses, protocols, and traffic volumes, enabling network administrators to identify anomalies, troubleshoot issues, and optimize network performance. sFlow is widely used in large-scale networks for its scalability and low overhead.

The biggest benefit of sFlow monitoring is that it keeps CPU load, bandwidth use, and memory utilization to an absolute minimum – great if your resources are limited or you operate in a sensitive environment. Of course, sFlow monitoring also has other compelling benefits. Having real-time visibility into your network's health makes it easier to allocate resources effectively, troubleshoot issues, and keep everything running smoothly.

sFlow is based on NetFlow, but differs from it in two key ways. First, it's an open standard. And, second, it monitors random samples of data, while NetFlow monitors every packet. IPFIX is also an open standard based on NetFlow. But, where sFlow uses sampling, IPFIX is template-based (though it can be configured to work with random samples, too).

Whether your network has sFlow, NetFlow, or IPFIX-compatible devices (or a mix of all three), PRTG has you covered!

In PRTG, “sensors” are the basic monitoring elements. One sensor usually monitors one measured value in your network, for example the traffic of a switch port, the CPU load of a server, or the free space on a disk drive. On average, you need about 5-10 sensors per device or one sensor per switch port.