DR in PIM-Bidirectional

from RFC 5015:
"The protocol presented in this document is largely based on the
      concept of a Designated Forwarder (DF). A single DF exists for
      each RPA on every link within a BIDIR-PIM domain (this includes
      both multi-access and point-to-point links). The only exception
      is the RPL on which no DF exists. The DF is the router on the
      link with the best route to the RPA (determined by comparing MRIB
      provided metrics). A DF for a given RPA is in charge of
      forwarding downstream traffic onto its link, and forwarding
      upstream traffic from its link towards the RPL. It does this for
      all the bidirectional groups that map to the RPA. The DF on a
      link is also responsible for processing Join messages from
      downstream routers on the link as well as ensuring that packets
      are forwarded to local receivers (discovered through a local
      membership mechanism such as MLD [3] or IGMP [2])."

So it looks like that DF has taken over every function of DR; is
something else left for DR to do in PIM-Bidirectional or is it made
completely redundant?

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Received on Sat Apr 24 2010 - 21:43:05 ART