CCIE Pursuit Blog

August 6, 2009

Core Knowledge Question of the Day: 06 August 2009

By default, when does a Cisco router switch over from the root-path-tree to the source-specific SPT?

Highlight for answer: When the first packet is received from the shared tree.  You can change this with the ‘ip pim spt-threshold’ command.


  1. By default, a cisco router switch over when the first packet is received on the RPT.
    Could be changed with : ip pim spt-threshold kbps|infinity

    Comment by morgan — August 26, 2009 @ 10:12 am | Reply

  2. Question Starts with ‘By Default’…. So, Bye default this command is not used. When this command is not used, the PIM leaf router joins the shortest path tree immediately after the first packet arrives from a new source.

    Comment by .a7. - Aditya Ghanekar. — December 8, 2009 @ 11:00 am | Reply

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