Subject: RE: PIM-DM spec comments

From: Bill Fenner <[email-masked]>
Date: Thu, 16 Dec 1999 08:51:11 -0800

>Shouldn't the hold time sent up in the prune be the minimum of
>hold times of prunes received on each downstream OIF. And if
>assert timer is running on the upstream, then minimum
>should be taken between this minimum hold time and assert time
>remaining.

I suggested this in Orlando but Liming said he would rather send
Grafts when the downstream prune timed out.  I didn't understand
why but he seemed to have his reasons.

>Also, while we have scheduled a prune on a LAN interface, due to
>prune received from a downstream neighbor, we might receive another
>prune from another neighbor on that interface with a lower hold time.
>In which case the prune timer for this OIF should be set to minimum
>across all prunes recieved from neighbors on this OIF. I don't think
>the draft mentions this.

Actually, it doesn't really mention using the prune hold-time in
the prune messages at all in section 5.2 -- it implies that you
should use a constant:

	At the time of the prune,  by  default, the  timer  SHOULD
	expire in [Data-Timeout - 3 seconds].

It's only later, in the timer section, when it mentions setting the
timer to the hold time in the packet.  I agree that the spec needs to
talk about reducing the prune timer.  It also needs to talk about not
raising it in response to a prune (e.g. in response to a packet,
router 1 sends a prune with 120 second hold time and router 2 sends
one with 180 second; the upstream had better use the 120 second one
no matter which order they arrive)

  Bill

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From: Chirayu Shah <[email-masked]>
Date: Thu, 16 Dec 1999 14:06:05 -0500

>no matter which order they arrive)

In addition, I think it needs to talk about what action needs to be
taken if a prune is received on an oif which is already pruned. Is the
new prune ignored or is the prune timer updated if necessary?

Chirayu.