Subject: [pim] RPF_INTF_STOPS_BEING_I

From: "Jyotheeswara Rao Kurma" <[email-masked]>
Date: Mon, 29 Oct 2001 21:49:18 +0500

Hi All:

   In (S,G) assert s/m if the RPF_INTF_STOPS_BEING_I event happens,
do we need to update the SPT bit to zero, if it is set by seeing
(S,G) assert on the upstream intf.  And change the correct input intf 
towards RP . Does Action A5, deleting assert info, means this also ??? 
(i.e resetting spt bit to zero, when moving to NO_INFO on the up-strm 
intf )

Current draft says  setting of this bit to 1, when movibg to Looser
on up-strm intf, when nothing tells about ressting it to zero, when 
moving back to NO_INFO on up-strm intf.

Thanks,
Jyotheesh

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From: John Zwiebel <[email-masked]>
Date: Mon, 29 Oct 2001 11:59:45 -0800

> moving back to NO_INFO on up-strm intf.

Yes.

First, remember the SPT-bit is only set when you receive data on the
IIF.

Therefore 1 reason you wait for the assert to set the SPT-bit is

   The upstream interface is the the same for both the RPT and SPT.
	Even though the downstream router may have sent a (S,G) join on
	the SPT, it can't send the (S,G,R) prune on the RPT until the 
	assert happens.  The SPT-bit is used to tell you when to send that
	prune.

Now, your question is about the IIF changing and so not directly related
to
the reason for waiting for the assert.  This portion of the spec is only
discussing asserts and FWIW, you are now in the No_info state WRT
asserts.
So now you need to refer to 4.2.2, where the last line in that section
refers
you to 4.4.7 "Sending (S,G) Join/Prune Messages".

This section is talking only about the upstream interface.  Since in
your
question, the RPF interface is no longer the same, then "JoinDesired"
for
that interface becomes false and the SPT-bit (for that interface) is
cleared.