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    Example: Configuring sFlow Technology to Monitor Network Traffic on EX Series Switches

    You can configure sFlow technology, designed for monitoring high-speed switched or routed networks, to continuously monitor traffic at wire speed on all interfaces simultaneously. sFlow data can be used to provide network traffic visibility information.

    This example describes how to configure and use sFlow monitoring. JUNOS Software fully supports the sFlow standard described in RFC 3176, InMon Corporation's sFlow: A Method for Monitoring Traffic in Switched and Routed Networks (see http://faqs.org/rfcs/rfc3176.html).

    Requirements

    This example uses the following hardware and software components:

    • JUNOS Release 9.3 or later for EX Series switches
    • One EX Series switch

    Overview and Topology

    sFlow technology is a statistical-sampling–based network monitoring technology for high-speed switched or routed networks. sFlow technology samples network packets and sends the samples to a monitoring station. The information gathered is used to create a network traffic visibility picture.

    An sFlow monitoring system consists of an sFlow agent embedded in the switch and a centralized collector. The sFlow agent runs on the switch. It combines interface counters and flow samples and sends them across the network to the sFlow collector. Figure 1 depicts the basic elements of the sFlow system.

    Figure 1: sFlow Technology Monitoring System

    Image g021065.gif

    Configuration

    To configure sFlow technology, perform the following tasks:

    CLI Quick Configuration

    To quickly configure sFlow technology, copy the following commands and paste them into the switch terminal window:


    [edit protocols sflow]
    set collector 10.204.32.46


    Set collector udp-port 5600
    set interfaces ge-0/0/0
    set polling-interval 20
    set sample-rate 1000

    Step-by-Step Procedure

    To configure sFlow technology:

    1. Configure the IP address of the collector:

      [edit protocols sflow]
      user@switch# set collector 10.204.32.46

      Note: You can configure a maximum of 4 collectors.

    2. Configure the UDP port of the collector. The default UDP port assigned is 6343.

      [edit protocols sflow]
      user@switch# set collector udp-port 5600
    3. Enable sFlow technology on a specific interface:

      [edit protocols sflow]
      user@switch# set interfaces ge-0/0/0

      Note: You cannot enable sFlow technology on a Layer 3 VLAN-tagged interface.

      You cannot enable sFlow technology on a link aggregation group (LAG) interface--that is, an aggregated Ethernet interface with a name such as ae0. You can enable sFlow technology on the member interfaces that make up the LAG.

    4. Specify how often the sFlow agent polls the interface:

      [edit protocols sflow]
      user@switch# set polling-interval 20

      Note: The polling interval can be specified as a global parameter also. Specify 0 if you do not want to poll the interface.

    5. Specify the rate at which packets must be sampled:

      [edit protocols sflow]
      user@switch# set sample-rate 1000

    Results

    Check the results of the configuration:

    [edit protocols sflow]
    user@switch# show
    polling-interval 20;
    udp-port 5600;
    sample-rate 1000;
    collector 10.204.32.46;
    interfaces ge-0/0/0.0;

    Verification

    To confirm that the configuration is correct, perform these tasks:

    Verifying That sFlow Technology Has Been Configured Properly

    Purpose

    Verify that sFlow technology has been configured properly.

    Action

    Use the show sflow command:


    user@switch> show sflow
    sFlow            : Enabled
    Sample limit     : 300 packets/second
    Polling interval : 20 seconds
    Sample rate      : 1:1000
    Agent ID         : 10.204.96.222

    Note: The sample limit cannot be configured and is set to 300 packets/second.

    Meaning

    The output shows that sFlow technology is enabled and specifies the values for the sample rate, sample limit, and polling interval.

    Verifying That sFlow Technology Is Enabled on the Intended Interface

    Purpose

    Verify that sFlow technology is enabled on interfaces and display the sampling parameters.

    Action

    Use the show sflow interface command:


    Interface       Status     Sample rate   Adapted sample rate    Polling-interval
     ge-0/0/0.0     Enabled       1000          16000                    20

    Note: The sample limit cannot be configured and is set to 300 packets/second.

    Meaning

    The output indicates that sFlow technology is enabled on the ge-0/0/0.0 interface with a sampling rate of 1000, sampling limit of 300 packets per second and a polling interval of 20 seconds.

    Verifying the sFlow Collector Configuration

    Purpose

    Verify the sFlow collector's configuration.

    Action

    Use the show sflow collector command:


    Collector address		UDP-port		No of samples
    10.204.32.46                    5600                    1000
    10.204.32.76                    3400                    1000

    Meaning

    The output displays the IP address of the collectors and the UDP ports. It also displays the number of samples.


    Published: 2010-09-21