Setup Guide

sFlow
sFlow is a standard-based sampling technology embedded within switches and routers which is used to monitor network trac. It is
designed to provide trac monitoring for high-speed networks with many switches and routers.
Topics:
• Overview
• Implementation Information
• Enabling and Disabling sFlow on an Interface
• Enabling sFlow Max-Header Size Extended
• sFlow Show Commands
• Conguring Specify Collectors
• Changing the Polling Intervals
• Back-O Mechanism
• sFlow on LAG ports
• Enabling Extended sFlow
Overview
The Dell EMC Networking Operating System (OS) supports sFlow version 5.
sFlow is a standard-based sampling technology embedded within switches and routers which is used to monitor network trac. It is
designed to provide trac monitoring for high-speed networks with many switches and routers. sFlow uses two types of sampling:
• Statistical packet-based sampling of switched or routed packet ows.
• Time-based sampling of interface counters.
The sFlow monitoring system consists of an sFlow agent (embedded in the switch/router) and an sFlow collector. The sFlow agent resides
anywhere within the path of the packet and combines the ow samples and interface counters into sFlow datagrams and forwards them to
the sFlow collector at regular intervals. The datagrams consist of information on, but not limited to, packet header, ingress and egress
interfaces, sampling parameters, and interface counters.
Application-specic integrated circuits (ASICs) typically complete packet sampling. sFlow collector analyses the sFlow datagrams received
from dierent devices and produces a network-wide view of trac ows.
Implementation Information
Dell EMC Networking sFlow is designed so that the hardware sampling rate is per line card port-pipe and is decided based on all the ports
in that port-pipe.
If you do not enable sFlow on any port specically, the global sampling rate is downloaded to that port and is to calculate the port-pipe’s
lowest sampling rate. This design supports the possibility that sFlow might be congured on that port in the future. Back-o is triggered
based on the port-pipe’s hardware sampling rate.
For example, if port 1 in the port-pipe has sFlow congured with a 16384 sampling rate while port 2 in the port-pipe has sFlow congured
but no sampling rate set, the system applies a global sampling rate of 512 to port 2. The hardware sampling rate on the port-pipe is then set
at 512 because that is the lowest congured rate on the port-pipe. When a high trac situation occurs, a back-o is triggered and the
hardware sampling rate is backed-o from 512 to 1024. Note that port 1 maintains its sampling rate of 16384; port 1 is unaected because it
maintains its congured sampling rate of 16384.:
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856 sFlow