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Setting up SPAN ports

In this guide we are going to look at how to setup SPAN ports on Cisco switches. The Switched Port Analyzer (SPAN) feature, sometimes called port mirroring or port monitoring, allows you to take a copy of network traffic as it passes through a network switch. You use it to send a copy of network packets seen on one switch port (or an entire VLAN) to another switch port. This copy can then be sent to a traffic analyzer such as NetFort LANGuardian.

SPAN ports have many benefits including:

  • Two SPAN ports available on all Cisco switches.
  • Gain visibility into what is happening on the LAN and WAN
  • Access to packet payloads which can be used for application decoding
  • More granular data for network troubleshooting (website names, usernames, file names, etc…)

Check out this short video which looks at how to setup a SPAN port on a Cisco switch.