Deployment Guide

sFlow

Dell Networking OS supports conguring sFlow.

Topics:

• Overview

• Implementation Information

• Enabling and Disabling sFlow

• Enabling sFlow Max-Header Size Extended

• sFlow Show Commands

• Conguring Specify Collectors

• Changing the Polling Intervals

• Changing the Sampling Rate

• Back-O Mechanism

• sFlow on LAG ports

• Enabling Extended sFlow

Overview

The Dell 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 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.

The default global sampling rate is 32768. The sampling rates are determined as follows:

• If the interface stats are up and the sampling rate is not congured on the port, the default sampling rate is calculated based on the line

speed.

744 sFlow