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Mini Howto on Cisco Systems RSPAN

Mini Howto on Cisco Systems RSPAN
Barney Gaumer – 01/25/2008

Ever get tired of grabbing your laptop and running into either the wiring closet or the datacenter to sniff a port or VLAN on a switch?  RSPAN could help if the jack at your desk is on a switch port located on the other side of a trunk.  As you read Cisco’s explanation below you will get the idea.  I’m also dropping a Visio to give a visual.

Overview of RSPAN
SPAN is a well-understood and widely used technology for mirroring traffic from one or more ports on a Cisco Catalyst switch (the SPAN source) to another port on the same switch (the SPAN destination). This is frequently called "local SPAN." Local SPAN has many important uses, including enabling users to capture and analyze traffic passing through a single switch.
RSPAN is another traffic-mirroring technology that allows users to extend the scope of their analysis to encompass multiple switches that are interconnected in the same Layer 2 domain. Pioneered on the Cisco Catalyst 6500 Series switches, RSPAN increases the flexibility afforded by the switch for port mirroring by allowing users to capture traffic on one switch, mirror it to a designated VLAN, and forward it to one or more ports on one or more other switches for analysis.
RSPAN software support is available in the following software releases for the Cisco Catalyst 6500 series switches:
    ·    Cisco Catalyst Operating System Software Release 5.3 and later
    ·    Cisco IOS® Software Release 12.1(13)E and later

There are specific limits on the number of local and remote SPAN sessions permitted on a given Cisco Catalyst 6500 Series system. These limits are documented in the Software Configuration Guides for the Cisco IOS Software and the Cisco Catalyst OS Software. For details, visit:
    ·    "Configuring Local SPAN and RSPAN" in the Cisco IOS Software Configuration Guide for Release 12.1E
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.1E/native/configuration/guide/span.html#1036881

Documentaion Source: Cisco Systems
http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a008017b753.shtml