Re: [v6ops] new draft: draft-yc-v6ops-solicited-ra-unicast
Owen DeLong <owen@delong.com> Tue, 21 July 2015 15:38 UTC
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From: Owen DeLong <owen@delong.com>
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References: <201507071147.t67Bl13m009348@irp-lnx1.cisco.com> <CAO42Z2x7mNFbB_w_+W+80pY+LeCAKXaOBXMmQvkcaMSWhwW60g@mail.gmail.com> <EF21B630-5D0A-415A-A93F-9058900CC80C@cisco.com> <CAO42Z2zAqMXhBZ2wa=q0wtHGhMpMWU9TSjfFyd2quiki9w0oSw@mail.gmail.com> <85CADAA2-8DF2-4A6B-812B-7A77081936F5@cisco.com> <CAO42Z2w3fOxGJHasKqYZRfGZ2u=7FnZBm+jgLtgDvfZ7HYW=iw@mail.gmail.com> <CAO42Z2z+DwOin23HQTysrZ9dNP924+LQ-vOExmJc_xZUEB4yCQ@mail.gmail.com> <228248C6-94FE-4C9C-A875-F732EFDC6601@cisco.com> <55AD3B64.5070400@acm.org> <CAPi140P+kfpyQKzCRDA7bZQRowQx_YRcZYa85hHe64g4AvsVTg@mail.gmail.com>
To: Andrew 👽 Yourtchenko <ayourtch@gmail.com>
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Cc: v6ops list <v6ops@ietf.org>, "draft-yc-v6ops-solicited-ra-unicast@tools.ietf.org" <draft-yc-v6ops-solicited-ra-unicast@tools.ietf.org>
Subject: Re: [v6ops] new draft: draft-yc-v6ops-solicited-ra-unicast
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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 <ayourtch@gmail.com> wrote: > > On 7/20/15, Erik Nordmark <nordmark@acm.org> 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 >> >>> >>> >>> _______________________________________________ >>> v6ops mailing list >>> v6ops@ietf.org >>> https://www.ietf.org/mailman/listinfo/v6ops >> >> _______________________________________________ >> v6ops mailing list >> v6ops@ietf.org >> https://www.ietf.org/mailman/listinfo/v6ops >> > > _______________________________________________ > v6ops mailing list > v6ops@ietf.org > https://www.ietf.org/mailman/listinfo/v6ops
- [v6ops] new draft: draft-yc-v6ops-solicited-ra-un… fred
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Kline
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Tore Anderson
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Fred Baker (fred)
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Fred Baker (fred)
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Fred Baker (fred)
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Ole Troan
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Fred Baker (fred)
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Kline
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Jen Linkova
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Kline
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Nordmark
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Tarko Tikan
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Sri Gundavelli (sgundave)
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew 👽 Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Gert Doering
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Ole Troan
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Kline
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Gert Doering
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Hemant Singh (shemant)
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Owen DeLong
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Nabil Benamar
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alejandro Acosta
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew 👽 Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew 👽 Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Jen Linkova
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew 👽 Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Jared Mauch
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Nabil Benamar
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Alexandru Petrescu
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Gert Doering
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Lorenzo Colitti
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Owen DeLong
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Owen DeLong
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Owen DeLong
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Nordmark
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Nordmark
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Nordmark
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Owen DeLong
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew 👽 Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Andrew 👽 Yourtchenko
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Ole Troan
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Nordmark
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Erik Nordmark
- Re: [v6ops] new draft: draft-yc-v6ops-solicited-r… Mark Smith