Subject: Re: PIM-SMv2 functional clarification - join latency

From: Liming Wei <[email-masked]>
Date: Tue, 24 Aug 1999 14:44:54 -0700 (PDT)

> From: Narayanan Vidya-CVN065 <[email-masked]>
> 
> I understood Dave's and Ravi's messages as contradicting each other. Maybe I
> am missing something here. It seemed like Dave said yes, you have to wait
> till the register suppression timer expires, while Ravi said that in section
> 3.2.1 of RFC 2362, it states that the RP sends a join/prune message in
> response to a (*,G) join that it receives. Please see my response to Ravi's
> mail that I sent before this one. 
> 
> So, I'm still not sure how this is supposed to work.

Here is what they said in English:

 1) If the RP has lost (S,G) state (due to any number of reasons including
    operator clearing state), the RP has to wait until the next
    (null) register to set up (S,G) state, and join again; (Dave)

 2) If the RP has not yet lost the (S,G) state, it should trigger a join
    to the source when the first member shows up. (Ravi)

-Liming

> 
> Vidya
> 
> 
> > See messages from Dave and Ravi, this is not specific to cisco's
> > implementation.
> > 
> > 
> > -Liming
> > 
>

---

From: Dave Thaler <[email-masked]>
Date: Tue, 24 Aug 1999 17:56:01 -0400 (EDT)

>     to the source when the first member shows up. (Ravi)

I agree, and the other part of my point was:
   
   3) The spec does not require that the RP keep (S,G) state for every 
      source, if it does not join back to the source.
      Hence, if the RP implementation decides not to keep such state for
      low data-rate sources, then (1) is the usual behavior.  If the RP 
      implementation always creates (S,G) state at the RP, then (2) 
      may be the usual behavior.  Obviously the RP implementor has a 
      tradeoff to make between state and join latency.

Hopefully this helps to explain how the answers are not contradictory.

-Dave

---

From: Narayanan Vidya-CVN065 <[email-masked]>
Date: Tue, 24 Aug 1999 16:37:51 -0500

Vidya

---

From: Liming Wei <[email-masked]>
Date: Tue, 24 Aug 1999 15:03:47 -0700 (PDT)

> From: Dave Thaler <[email-masked]>
> 

I agree on point 3 too. The implementator's freedom to make a decision
is a feature of the spec in that it accommodates implementations with
different resource constraints and requirements.

-Liming