Subject: PIM MIB: augmenting ipMRouteTable and ipMRouteNextHopTable?

From: Bill Fenner <[email-masked]>
Date: Wed, 28 Oct 1998 13:23:27 PST

PIM Sparse Mode defines two bits associated with entries in the multicast
forwarding table: the SPT-bit and the RPT-bit.  It's not possible to
understand how packets are being forwarded without knowing the values of
these bits.

PIM Assert processing can modify the flow of traffic; if you don't know
that a change was caused by an Assert it's easy to get confused by the
information in the ipMRouteTable and ipMRouteNextHopTable.

Therefore, I'd like to get input on adding 2 tables to the PIM MIB:

pimMRouteTable, which augments ipMRouteTable
	contains SPT-bit, RPT-bit, and upstream Assert info: Assert-Timer,
	    and possibly including the metric and metric-pref of the winning
	    Assert

pimMRouteNextHopTable, which augments ipMRouteNextHopTable
	contains downstream Assert info - possibly just the fact that
	    the downstream interface was pruned due to Assert, possibly
	    also the metric and metric-pref of the winning Assert.

Also, in PIM-DM, each NextHop interface has a prune timer; what isn't
clear is whether that's the same as the ipMRouteNextHopExpiryTime or if
it would need its own pimMRouteNextHopPruneTimer.  (i.e. it's not
exactly clear what the MRouteMIB means by "aged out").

Any comments?

Thanks,
  Bill