Re: [dhcwg] WGLC for draft-ietf-dhc-rfc3315bis-08 - Respond by May 30th, 2017

[Timothy Winters <[e-mail]>]

Hi Bernie,

We have CE Routers that countdown from when the IA_PD is received, and
others that always transmit the lifetime received in the IA_PD in RA
(Always the same).   It's about 50/50 at the moment.   When we were working
on testing for 6024/7084 this was a topic that was discussed but it wasn't
clear answer on what to do with the lifetimes.

You are correct that when the prefix timeout from the IA_PD it will stop
forwarding and transmit a Destination Unreachable message.

Regards,
Tim

On Mon, Jun 19, 2017 at 2:10 PM, Bernie Volz (volz) <[e-mail]> wrote:

> I’ve added Tim Winters as perhaps he can shed some light on this in terms
> of what is tested at the NH Interoperability Lab for PD / CPEs?
>
> Even if a device doesn’t follow this (running down the lifetimes), what’s
> likely to happen when the PD expires is that the traffic will hopefully no
> longer be forwarded by the router (and with a ICMP destination unreachable
> notification) and perhaps RAs will be sent with 0 lifetimes to attempt to
> deprecate the prefix (and any assigned addresses) use as quickly as
> possible?
>
> Ralph or Ole might also have a comment with respect to what they expected
> a requesting router to do based on the original RFC 3633? I don’t think
> this 3315bis document itself caused this potential confusion to exist?
>
> - Bernie
>
> On 6/19/17, 1:55 PM, "JINMEI Tatuya / 神明達哉" <[e-mail]>
> wrote:
>
>     At Sat, 17 Jun 2017 02:27:39 +0000,
>     "Bernie Volz (volz)" <[e-mail]> wrote:
>
>     > My reaction is you are wrong – the PIO would, whenever sent, be sent
>     > with the preferred and valid lifetime REMAINING on the PD lease. So,
>     > sure a PIO sent just after the PD lease started would have (close)
>     > to the full values, but the values sent an hour later would be 1
>     > hour less than they were.
>
>     Actually I agreed.  I guess what we're different is the view on how
>     obvious it is.  I suspect this is not so obvious and there are
>     actually implementations that can cause the situation where
>     deprecated/invalidated addresses are used.  There may even be an
>     implementation that naively copies the lifetimes from PD to RA PIO.
>
>     I've monitored RAs advertised in my apartment room.  The ISP is
>     Comcast and the default router is Apple time capsule.  The lifetimes
>     advertised in RA PIO are constant and do not decrease as I monitored
>     it in multiple consecutive RAs.  Of course, it doesn't immediately
>     mean the time capsule device uses the 'naive' approach.  I actually
>     don't even know if PD is used or the time capsule is the PD client.
>     And the time capsule might actually have some safety buffer period and
>     use a much lower lifetimes for PIO than those provided in PD.  Still,
>     I think this can be a potential anecdote to suggest there might be a
>     problematic implementation.
>
>     So I don't think it at least doesn't harm if we say that lifetimes of
>     site addresses derived from the delegated prefix MUST NOT exceed the
>     remaining time of the lifetimes in the last-received corresponding
>     PD.  (I don't think we have to specify exactly how to implement this
>     restriction).
>
>     --
>     JINMEI, Tatuya
>
>
>


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