Subject: RE: doubts regarding assert mechanism in PIM SM

From: Billy Ng <[email-masked]>
Date: Wed, 29 Mar 2000 09:15:18 -0500

The assert loser shuts itself off at the OI on the upstream,
and if that OI is the last one, it will trigger a prune
upstream.  Therefore, there is no need for the downstream
to send the prune when it switches its RPF neighbor.

--Billy

> -----Original Message-----
> From: Renu Agarwal [mailto:[email-masked]]
> Sent: Tuesday, March 28, 2000 11:39 PM
> To: sabarivel s
> Cc: [email-masked]'
> Subject: Re: doubts regarding assert mechanism in PIM SM
> 
> 
> Hello sabarivel,
> Please see my replies.  
> 
> Hope it helps,
> 
> Renu
> sabarivel s wrote:
> > 
> > hi ,
> >  i have some doubts regarding the assert mechanism (refer 
> PIM -sm rfc 2362
> >  section 3.5)
> > 
> > 1) in the section 3.5.2.2 Receving asserts on an entry's 
> incoming interface
> > 
> > doubt :  if the assert does not match the entry exactly it 
> is ignored.What
> > do u mean by exact entry in this context ?
> >         is the RPT bit of the assert messages are taken 
> care in this case?
> >              i.e if the RPT bit is cleared exact matching 
> entry is (s,g)
> >          and if RPT bit is exact matching entry is (*,G) . Is it so?
> 
> If RPT-bit is set then depending on the group address present match it
> exactly with (*,G) or (*,*, RP).
> 
> else
> 	match with (S,G)entry
> 
> > 
> > doubt :  When the RPF neighbour changes Assert timer has to 
> be started ..
> > and random delay join timer also need to be started.
> >         Which timer has to be started first?
> 
> The timers has to be started simultaneously. In my opinion, 
> the sequence
> is immaterial.
> > 
> > 2)  in the same section 3.5.2.2. point no 2 is
> > If the downstream routers have downstream members and if 
> the assert caused
> > the RPF neighbour to change the downstream routers must trigger a
> > join/prune message to inform the upstream router that 
> packets are to be
> > forwarded on the multiaccess network.
> > 
> > doubt: whether a prune has to be sent to the old RPF 
> neighbour? if prune is
> > to be sent ,whether join/prune suppression timer
> > has to be started by other routers parallel to it?
> The RFC nowhere specifies the prune is to be sent. It assumes that the
> old RPF shall automatically time-out the entry in absence of 
> join-prune
> message.
> 
> >           when the downstream routers don't have downstream 
> members what to
> > do?
> This is totally different case. If a downstream router has no 
> downstream
> members or routers using that entry, this entry shall any way be
> deleted/timed-out.
> > 
> > thanks in advance
> > with regards
> > sabaris
>