====== Reference ======
  * Troubleshooting Multicast RPF failure
    * http://blog.ine.com/2008/01/02/troubleshooting-multicast-rpf-failure/
  * PIM Sparse Mode
    * http://wiki.nil.com/PIM_Sparse_Mode
  * http://www.petri.co.il/forums/showthread.php?t=47148
  * IP Multicast Troubleshooting
    * https://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a0080094b55.shtml
  * Multicast Quick Configuration Guide
    * https://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a0080094821.shtml
    * see also links at bottom of page
  * Basic Multicast Troubleshooting Tools
    * https://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a0080093f21.shtml
  * Source Specific Multicast with IGMPv3, IGMP v3lite, and URD
    * https://www.cisco.com/en/US/docs/ios/12_1t/12_1t5/feature/guide/dtssm5t.html
  * IP Multicast Troubleshooting Guide
    * http://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a0080094b55.shtml

===== Configurations =====
  * Multicast SSM config - basic lab setup
    * https://supportforums.cisco.com/message/599135#599135