http://www.cisco.com/en/US/docs/solutions/Enterprise/Campus/HA_campus_DG/hacampusdg.html#wp1108495
http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a008019e74e.shtml
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http://www.informit.com/library/content.aspx?b=CCNP_Studies_Switching&seqNum=51
http://www.cisco-tips.com/how-to-configure-a-cisco-layer-3-switch-intervlan-routing/