Subject: RE: W bit

From: "Shekhar, Ravi" <[email-masked]>
Date: Wed, 13 Oct 1999 16:39:21 -0400

> >   My understanding is that this could potentially result in 
> a vicious circle
> > 
> >   of prune overriding messages.
> > 
> 
> Agree for a shared LAN, but even a (S1,G)RPT join is not going to help
> since it has the same effect as a (*,G) join that does not include
> the (S1,G)RPT prune.  The upstream router will see a prune then a join
> to override the prune in either case.

  Well, <S1, G>RPTjoin will only join S1. Any S3, which has been pruned by
  all downstream routers, will not get joined by it. Whereas a <*, G> join 
  will result in joining not just <S1, G> but also <S3, G>. 

  - Ravi Shekhar. 

> >   Consider two routers: R1 with <*, G>join<S1, G>prune and R2 with
> >   <*, G>join<S2, G>prune state. 
> > 
> >   Lets say R1 sends <*, G>join<S1, G>prune to override some prune.
> >   Now in order to override R1's <S1, G>prune, R2 will send 
> <*, G>join<S2,
> > G>prune. 
> >   And then to override R2's <S2, G>prune, R1 will again 
> send <*, G>join<S1,
> > G>prune
> >   ..... and so on....
> > 
> >   One can do tricks with set-intersection of S's but if you 
> increase the
> >   number of routers on the LAN, even that will end up 
> generating quite a few
> >   number of messages in the worst case.
> > 
> >   - Ravi Shekhar.
> > 
>