Re: [v6ops] new draft: draft-yc-v6ops-solicited-ra-unicast
Erik Nordmark <nordmark@acm.org> Thu, 23 July 2015 16:26 UTC
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To: Mark Smith <markzzzsmith@gmail.com>, Erik Nordmark <nordmark@acm.org>
References: <201507071147.t67Bl13m009348@irp-lnx1.cisco.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> <CAAedzxqapiWuy4Gk5t3zEe3XmaLyRc3nc5=aA1ED0tzfeXckbA@mail.gmail.com> <CAKD1Yr3Hn9qJTaM0v3+hr7NfQbLc=mOWYGwrTK-XXxKp5v+dpg@mail.gmail.com> <CAAedzxpdFsCy2Y7U0gFmQeHEvJjNj-243g_ffoJsVUeRz5RpZw@mail.gmail.com> <CAKD1Yr1uR+HyBTB=Yhy5hGs1Z6Wv=HT3wwFgLYDosDJ7a78-PA@mail.gmail.com> <D1D2A832.1B7D8F%sgundave@cisco.com> <CAAedzxoX1dD3MQO5YCS6+u1esThW0sVv=JMmivJXZ92FKZ0sZg@mail.gmail.com> <CAO42Z2w8D+G7ONS5uXDP2kgf4da2JgiHHubEMt3TVumfFbkWOA@mail.gmail.com> <55B0177F.8050703@acm.org> <CAO42Z2yTrjLudtCnbR_ziTGAKYkwtCguF+yEB4e78jEVUUT-Cg@mail.gmail.com>
From: Erik Nordmark <nordmark@acm.org>
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Date: Thu, 23 Jul 2015 18:26:14 +0200
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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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On 7/23/15 2:37 AM, Mark Smith wrote: > Hi Erik, > > On 23 July 2015 at 08:21, Erik Nordmark <nordmark@acm.org> wrote: >> On 7/21/15 1:25 PM, Mark Smith wrote: >>> >>> I thought that could be an option, however I encountered RSes without >>> the Source Link Layer Option, which means if RFC6085 is to be used, >>> the link-layer header has to be available to get the source link-layer >>> address from. >>> >>> After I wondered about the efficiency benefit of using multicasts for >>> solicited RAs, Fred asked me to do some testing/investigation. I wrote >>> up what I found here, the few unusual RS cases I saw the following, >>> which I put down some thoughts about handling via e.g., RFC6085. >>> >>> o RSes with a :: source address >>> >>> o RSes with a link-local source addresses, but no Source Link-Layer >>> Address Option >> >> Yes, both of those are important (I had forgotten about the second one). >> >> As you say, an implementation might be able to use the link-layer header and >> unicast back a packet. If the source was :: then that approach would rely on >> sending to the multicast ff02::1 while the link-layer destination is >> unicast. >> >> If not, then the implementation needs to multicast the RA. >> > I was wondering if instead the implementation could trigger an ND/NS > transaction for the RS source address at that point, and then unicast > the RA when that completes. That would only address the lack of SLLAO case; not the unspecified source address case. I don't know how common these cases are in existing implementations. The unspecified source would appear if the host is doing DAD in parallel with sending the RS. I don't know when a host would omit the SLLAO in the RS. > > RFC4861 seems to be a bit vague about being able to do that. It says > that if the SLLO is not present, the router still can unicast the RA. > As RFC4861 is pre RFC6085, then performing a ND/NS first would be the > only way to do that. The last sentence also seems to be permitting NC > entries to be created when there is no SLLO ("or not a Source > Link-Layer is provided" ... "Neighbor Cache entry" ... "(or is > created)"). > > "If there is no existing Neighbor Cache > entry and no Source Link-Layer Address option was present in the > solicitation, the router may respond with either a multicast or a > unicast router advertisement. Whether or not a Source Link-Layer > Address option is provided, if a Neighbor Cache entry for the > solicitation's sender exists (or is created) the entry's IsRouter > flag MUST be set to FALSE." I think the attempt at english as opposed to pseudo-code is hard to read. AFAIK the intent was if NCE set NCE IsRouter to FALSE Thus the NCE might have already existed, or have been created. I think there is text earlier to say to not create an NCE for 0::0 nor if there is no SLLAO (unless the link-layer has no addresses). Regards, Erik > > Performing an NS/ND to resolve the source address of the RS without a > SLLO would seem consistent with the corresponding RS SLLO handling - > to load the Neighbor Cache with entries for nodes that have sent RSes. > > > Regards, > Mark. > >> Erik >> >>> https://www.ietf.org/mail-archive/web/v6ops/current/msg22464.html >>> >>> >>> >>> >>> https://www.ietf.org/mail-archive/web/v6ops/current/msg22464.html >>> >>>> But I would not say it's sufficient, if only from an "explicit >>>> clarity" standpoint. I think explicit mention of RAs and the other >>>> discussion is helpful for implementors not inclined to dig to great >>>> depths or just seeking explicit confirmation. >>>> >>> >>> >>>> _______________________________________________ >>>> 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