Re: [v6ops] new draft: draft-yc-v6ops-solicited-ra-unicast

[Alexandru Petrescu <[e-mail]>]

Le 22/07/2015 14:31, Jen Linkova a écrit :
> On Wed, Jul 22, 2015 at 2:12 PM, Alexandru Petrescu
> <[e-mail]> wrote:
>>
>> "... on Androids and iPhones"?
>>
>> But not on huawei E392.
>
> I'm not sure what the fact that huawei E392 is not affected by a
> particular issue proves.
> So far we know that
> - there are platforms affected;
> - there is one unaffected platform.

I think we discuss here a smartphone world.

Android and smartphones in general are great things that happened to 
Internet, but there is more to it: raspberry pis, and various other 
small yet non-smartphone platforms.

Alex


>
> Therefore I believe it is perfectly find for the title to be 'Reducing
> battery impact of Router Advertisements'. If a particular network and
> its devices are not affected - good, the network administrators MAY
> (or SHOULD?) ignore the draft and not apply the recommendations.
>
>> Le 22/07/2015 14:10, Lorenzo Colitti a écrit :
>>>
>>> I'm told the problem affects iPhones as well.
>>>
>>> On Wed, Jul 22, 2015 at 2:07 PM, Alexandru Petrescu
>>> <[e-mail] <mailto:[e-mail]>> wrote:
>>>
>>>      "Reducing battery impact of RAs on Androids"?
>>>
>>>      Alex
>>>
>>>      Le 22/07/2015 12:22, Lorenzo Colitti a écrit :
>>>
>>>          Thanks for all the feedback. We have posted a -01 addressing
>>>          some of the
>>>          feedback we got. The new version also contains a new
>>>          recommendation not
>>>          to send periodic RAs too frequently, so we have changed the title to
>>>          "Reducing battery impact of Router Advertisements".
>>>
>>>          https://tools.ietf.org/html/draft-yc-v6ops-solicited-ra-unicast-01
>>>
>>>          If there are no objections, we will upload this as a WG document
>>>          in the
>>>          next few days.
>>>
>>>          On Wed, Jul 22, 2015 at 5:09 AM, Alejandro Acosta
>>>          <[e-mail]
>>>          <mailto:[e-mail]>
>>>          <mailto:[e-mail]
>>>          <mailto:[e-mail]>>>
>>>          wrote:
>>>
>>>               Hi There,
>>>                  I also support this document, it's very positive to see
>>>          that this
>>>               algorithm will save energy.
>>>
>>>               Regards,
>>>
>>>               Alejandro,
>>>
>>>               El 7/21/2015 a las 6:11 PM, Nabil Benamar escribió:
>>>
>>>                   Hi Folks,
>>>
>>>                   I support this document which is very informative,
>>>              useful and its
>>>                   implementation will certainly reduce energy consumption
>>>              due to
>>>                   excessive Multicast RA sent. The proposed algorithm
>>>              seems to be
>>>                   suitable for this end !
>>>
>>>
>>>                   Best regards
>>>
>>>
>>>
>>>                   On Tue, Jul 21, 2015 at 4:38 PM, Owen DeLong
>>>              <[e-mail] <mailto:[e-mail]>
>>>                   <mailto:[e-mail] <mailto:[e-mail]>>> wrote:
>>>
>>>                       It seems to me that the following algorithm would be
>>>                       relatively easy to implement
>>>                       and provide reasonable network optimization…
>>>
>>>
>>>                       On receipt of an RS:
>>>
>>>                               if(multicast_ra_time_remaining > 15 seconds)
>>>                               {
>>>                                 Send_Unicast_ra
>>>                               }
>>>                               else
>>>                               {
>>>                                 Send_Multicast_ra
>>>                                 reset_multicast_timer
>>>                               }
>>>
>>>                       In this way, if the timing is reasonably close, you
>>>              multicast
>>>                       a packet you were about to send
>>>                       anyway, but if the timing isn’t close, you’re not
>>>              wasting
>>>                       multicast bandwidth answering a single
>>>                       node where nobody else cares.
>>>
>>>                       Overall, I’ve always thought that multicast
>>>              response to RS was
>>>                       kind of silly. It’s probably most
>>>                       harmful on WiFi.
>>>
>>>                       Owen
>>>
>>>                       > On Jul 21, 2015, at 02:33 , Andrew Yourtchenko
>>>                       <[e-mail] <mailto:[e-mail]>
>>>              <mailto:[e-mail] <mailto:[e-mail]>>> wrote:
>>>                       >
>>>                       > On 7/20/15, Erik Nordmark
>>>                       <<mailto:[e-mail]
>>>              <mailto:[e-mail]>>[e-mail]
>>>              <mailto:[e-mail]>
>>>
>>>                       <mailto:[e-mail]
>>>              <mailto:[e-mail]>>> wrote:
>>>                       >> On 7/17/15 9:34 AM, Fred Baker (fred) wrote:
>>>                       >>>> So the next logical thing to do would be to
>>>              have the
>>>                       router default to
>>>                       >>>> unicast Router Advertisements, measure the rate of
>>>                       received Router
>>>                       >>>> Solicitations, and switch to multicast RA mode
>>>              past a certain
>>>                       >>>> threshold to cover this sort of situation.
>>>              Once the
>>>                       number of RSes
>>>                       >>>> falls, it switches back to unicast RA mode.
>>>                       >>>>
>>>                       >>>> That would get rid of the configuration knob
>>>              proposed in
>>>                       this ID, and
>>>                       >>>> is behaviour that I think could be universal
>>>              for all link
>>>                       types,
>>>                       >>>> rather than just for the case of wireless ones
>>>              with
>>>                       mobile devices.
>>>                       >>> If it were me implementing it, I think I would
>>>              go about
>>>                       this in a little
>>>                       >>> different way, hopefully simpler. I would want
>>>              to send at
>>>                       most one (e.g.,
>>>                       >>> either zero or one) RA per some interval (a
>>>              second?). In
>>>                       the normal case,
>>>                       >>> that is sent unicast. However, having sent a
>>>              unicast RA at
>>>                       time t, if I
>>>                       >>> now receive another RS before t+1, I send the
>>>              next one (at
>>>                       time t+1) as a
>>>                       >>> multicast.
>>>                       >>
>>>                       >> First of all I support this document as a WG
>>>              document.
>>>                       >>
>>>                       >> But in terms of implementation, isn't it simpler to
>>>                       always(*) respond to
>>>                       >> a RS with a unicast RA?
>>>                       >
>>>                       > Yes. I did not respond on-list yet - but from
>>>              operational
>>>                       perspective
>>>                       > "always send solRA unicast" / "always send solRA
>>>              multicast"
>>>                       definitely
>>>                       > wins in my book, and I'd avoid premature
>>>              optimizations (but
>>>                       maybe we
>>>                       > can say the implementers are explicitly free to
>>>              do their own
>>>                       > optimizations if they see fit)
>>>                       >
>>>                       > That said, will be very interesting to hear data
>>>              from folks
>>>                       who will
>>>                       > run "all-unicast solRA", in real networks and
>>>              then compare
>>>                       the effect
>>>                       > of their proposal optimizations on their
>>>              real-world scenarios.
>>>                       >
>>>                       >> As background, the text in RFC4861 comes from
>>>              the old
>>>                       concern that all
>>>                       >> devices might boot at the same time when the
>>>              power is
>>>                       re-established
>>>                       >> after a building power failure; that doesn't
>>>              happen since
>>>                       most devices
>>>                       >> (laptops, smartphones, IoT devices) have
>>>              batteries today.
>>>                       In that case
>>>                       >> it might have made sense to sending fewer RA
>>>              messages by
>>>                       using multicast.
>>>                       >>
>>>                       >> (*) the only case in RFC 4861 when I think a
>>>              multicast
>>>                       response might be
>>>                       >> considered is when the source IPv6 address in
>>>              the RS is the
>>>                       unspecified
>>>                       >> address. Further, an implementation which rate
>>>              limits
>>>                       received RS
>>>                       >> packets (e.g., CoPP in a router) might also want
>>>              to detect
>>>                       when the rate
>>>                       >> limit might have dropped RS packets and
>>>              multicast an RA in
>>>                       that case.
>>>                       >>
>>>                       >>
>>>                       >> I do wonder why implementations haven't already
>>>              changed to
>>>                       send unicast
>>>                       >> solicited RA, and whether it would make a
>>>              difference if we
>>>                       have an
>>>                       >
>>>                       > TBH that's my concern as well. I think we should
>>>              tweak the
>>>                       text in
>>>                       > 4861 to encourage a bit more consideration on the
>>>                       implementer's side.
>>>                       >
>>>                       >> informational document asking them to do this.
>>>                       Alternatively we could
>>>                       >> have a proposed standard which updates section
>>>              6.2.6 to
>>>                       change the "MAY
>>>                       >> unicast" to a "SHOULD unicast".
>>>                       >
>>>                       > Yeah, I actually have had the different text
>>>              aimed for 6man, but
>>>                       > Lorenzo's concern was 6man would say "there is no
>>>              protocol
>>>                       update
>>>                       > here, go away", so he rewrote it for v6ops.
>>>                       >
>>>                       > We should probably discuss this at the mic and
>>>              get the
>>>                       opinion of the
>>>                       > 6man chairs - if there is no outright "no" on this, a
>>>                       normative doc
>>>                       > would be a better way to convince the implementers ?
>>>                       >
>>>                       >>
>>>                       >> FWIW the draft incorrectly refers to section
>>>              6.2.4 instead
>>>                       of 6.2.6.
>>>                       >
>>>                       > Nice catch, thanks!
>>>                       >
>>>                       > --a
>>>                       >
>>>                       >>
>>>                       >> Thanks,
>>>                       >>    Erik
>>>                       >>
>>>                       >>>
>>>                       >>>
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