RE: Updated IID length text

"Manfredi, Albert E" <albert.e.manfredi@boeing.com> Thu, 19 January 2017 03:30 UTC

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From: "Manfredi, Albert E" <albert.e.manfredi@boeing.com>
To: Brian E Carpenter <brian.e.carpenter@gmail.com>, 6man <ipv6@ietf.org>
Subject: RE: Updated IID length text
Thread-Topic: Updated IID length text
Thread-Index: AQHScexT724zBn76p0KKsEzsg727/qE/EBsQgAAKfeCAAI6ZgP//evLg
Date: Thu, 19 Jan 2017 03:30:27 +0000
Message-ID: <663e5d5032a94f18b91b6a1dedcb8da7@XCH15-06-11.nw.nos.boeing.com>
References: <148406593094.22166.2894840062954191477.idtracker@ietfa.amsl.com> <m2fukqbbwv.wl-randy@psg.com> <F6953234-3F85-4E28-9861-433ADD01A490@gmail.com> <m2wpdzhncn.wl-randy@psg.com> <82245ef2-cd34-9bd6-c04e-f262e285f983@gmail.com> <m2d1frhjfn.wl-randy@psg.com> <18e6e13c-e605-48ff-4906-2d5531624d64@gmail.com> <CAKD1Yr1cvZ8Y3+bHeML=Xwqr+YgDspZGnZi=jqQj4qe2kMc4zw@mail.gmail.com> <m2lguffnco.wl-randy@psg.com> <CAKD1Yr1TrTiPRdyutobmb_77XJ7guNzLrg=H_p7qi4BfQ8V=GA@mail.gmail.com> <m2d1frfm6m.wl-randy@psg.com> <CAKD1Yr2Njjd8_Mr+6TRFF6C5pdcX4yFgpFVyEkykDuytu2B8mg@mail.gmail.com> <2A5073777007277764473D78@PSB> <4596c3d4-a337-f08e-7909-f14270b7085f@gmail.com> <CAN-Dau06R3iYRpYLADhvHox4C9qdsJCuxFsJapRhOQcWT4qk_g@mail.gmail.com> <CAO42Z2weZcoHiBzN94QAQ9WGhWR16PmMMFNg=5YLmr_dhPjjpA@mail.gmail.com> <fcc7f136-b5da-527e-b495-5a2d7f7a3ce8@gmail.com> <55bb8bdbfbf4439da0aa702e5bc03e2c@XCH15-06-11.nw.nos.boeing.com> <bb79ce41f2cc465dab0a7f26466be26f@XCH15-06-11.nw.nos.boeing.com> <ed9fe2df-0dce-0ddc-bdee-561217d089bb@gmail.com>
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-----Original Message-----
> From: Brian E Carpenter [mailto:brian.e.carpenter@gmail.com]
 
> On 19/01/2017 15:55, Manfredi, Albert E wrote:
> ...
> >> I don't think that SLAAC *must* require a single standard IID length, so
> >> that's why I added the word "robust." Now that we have moved away from
> using
> >> the MAC address for SLAAC, it's not clear to me why a host cannot wait for
> a
> >> RA, and then decide on how many IID bits to use, based on the prefix
> >> length(s) advertised by the router.
> 
> Not if you want to form a link-local address first. Which you always do,
> because perhaps there *is* no router when you come up after a power cut.
> (In the Anima WG, we are very interested in the behaviour of nodes
> that have absolutely no external information when they come up, because
> it's their job to bootstrap the network out of nowhere.)

Right, but you can differentiate that link local address from global addresses, so you can require it to have 64-bit IIDs. It's for the global addresses that I think we don't want to repeat the CIDR lessons of the past. Ditto for ULAs, for example.

Bert