RFC 4601, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", August 2006

Note: This RFC has been obsoleted by RFC 7761

Note: This RFC has been updated by RFC 5059, RFC 5796, RFC 6226

Errata ID: 1121
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Maren Peasley
Date Reported: 2007-12-21
Held for Document Update by: David Ward
Date Held: 2009-03-22

Section 4.5.4 says:

     Prune-Pending (PP)
          The router has received a Prune(S,G,rpt) on this interface
          from a downstream neighbor and is waiting to see whether the
          prune will be overridden by another downstream router.  For
          forwarding purposes, the Prune-Pending state functions exactly
          like the NoInfo state.

Notes:

If a single Prune(S,G,rpt) stops forwarding, then traffic can be interrupted even when it is still needed. There is a random delay between 0 and Effective_Override_Interval(I) (0 – 2.5 seconds by specification defaults) in which traffic stops until it is overridden and traffic starts flowing again. This appears to be an optimization for efficiency vs. reliability. I believe that this should be noted and made into an optional optimization.

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