Subject: [pim] BIDIR-PIM: Mechanism needed for RP to prune upstream traveling pa ckets

From: Harry Zhang <[email-masked]>
Date: Fri, 30 Aug 2002 13:23:20 -0500

I have a few questions about Bi-directional Protocol Independent Multicast.

1. The draft addresses resource saving with a shared tree. It did not
mention (S, G, rpt) state in chapter 3.4. Does this mean that even (S, G,
rpt) state is saved or imply that the state remains unchanged as defined by
PIM-SM? I think it remains unchanged, otherwise too much bandwidth will be
unnecessarily wasted.

2. The draft did not provide a mechanism for RP to prune (S, G) state from
each DF's outgoing list, (upstream traveling towards the RP), if the RP has
no interest in the session. Does this also intend to save resources or
simplify the algorithm? If each router still maintains (S, G, rpt) state,
this probably saves nothing significantly. But it will not be acceptable,
because too much bandwidth will be lost, unless the RP is very close to the
source. The assumption may not always be true.

3. I also do not believe that SPTbit(S,G) can be saved together with (S, G)
state.

Thanks,

Harry

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