Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Addressing Architecture) to Internet Standard

Alexandre Petrescu <alexandre.petrescu@gmail.com> Mon, 27 February 2017 16:58 UTC

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Subject: Re: Last Call: <draft-ietf-6man-rfc4291bis-07.txt> (IP Version 6 Addressing Architecture) to Internet Standard
To: Lorenzo Colitti <lorenzo@google.com>, =?UTF-8?B?56We5piO6YGU5ZOJ?= <jinmei@wide.ad.jp>
References: <20170221001940.GB84656@Vurt.local> <068ce975-8b1e-a7c5-abba-2bfc1d904d70@gmail.com> <20170221101339.GC84656@Vurt.local> <CAKD1Yr33oQb=gMGaEM++hLgmMtxMdihiDrUihEsjs63vy8qRbA@mail.gmail.com> <54c81141-e4f5-4436-9479-9c02be6c09bb@Spark> <CAKD1Yr28iQHt0iuLvR3ndrT3Hfct=4k9dxjJeu3MAjDjOogEvA@mail.gmail.com> <CAL9jLaZgTp++PJ9KGHEWuPoVm6t3b8QfVDCEhz5h4fv-0fuUAA@mail.gmail.com> <CAKD1Yr3SbR=xt3RPu7+q1o14wKuUuwUc6oG+BgZtEK1O+m5sWw@mail.gmail.com> <4936e96b-fc82-4de0-9188-ced9547deb2f@Spark> <CAKD1Yr3K+SJb_4ksZ96yNypVKJE-fXopuVaXNhhKp1gkh1=QEg@mail.gmail.com> <20170222144147.GC89584@hanna.meerval.net> <7960ff2d-359f-429c-6e82-ef592f90bf53@gmail.com> <CAKD1Yr1W+AVt4Dixo9epB5VazxBsVMD+mrshwaE=n7SuX6eGDw@mail.gmail.com> <5ce34926-6bde-6410-9b1e-3f61e48e9a1d@gmail.com> <CAKD1Yr1yRTUPVTTicaTkA8fAFxHiHxdLG8ZzEHjCUDDzKg5zJg@mail.gmail.com> <CAJE_bqe=4KruMwWOnSF7RO7TOQTdx48cG_4uSPkGptkG7R4ckw@mail.gmail.com> <CAKD1Yr3oDODYbXzrdjttWQNWBQqgFJQiJtx-ti0uwK-AwHevPw@mail.gmail.com>
From: Alexandre Petrescu <alexandre.petrescu@gmail.com>
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Date: Mon, 27 Feb 2017 17:58:03 +0100
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Le 27/02/2017 à 16:40, Lorenzo Colitti a écrit :
> On Fri, Feb 24, 2017 at 3:45 AM, 神明達哉 <jinmei@wide.ad.jp
> <mailto:jinmei@wide.ad.jp>> wrote:
>
> Out of curiosity: which code is it, and exactly what does its
> assumption mean?  Does it mean, for example, it allows manual
> configuration of an address but requires its IID length be 64 bits?
>
>
> The first example that came to mind was one in the Android 464xlat
> implementation. This takes the IPv6 prefix configured on the
> interface, fills the bottom 64 bits with randomness, adjusts the
> middle bytes to make the result checksum-neutral, and uses that as
> the IID. If we change the IID to != 64 bits, then that code becomes
> incorrect.

For my part, I agree with you: we want that IID len to continue working
with 464xlat.

I dont appreciate the confusion android - and linux for that matter
- introduces when adding by default an fe80::/64 entry in the routing
table.  I dont mind the route, but I mind the 64.

I dont appreciate the linux kernel complaining when receiving a plen==65
in RA.

I think text in 4291bis - if any text - should allow the first case
(IID==64 for 464xlat), but disallow the other two cases (fe80::/64 by
default in linux rt, and linux kernel complaining of plen==65 in RA).

I.e. text in 4291bis - if any text - should allow IID==64, RA plen==65
but should disallow by-default fe80::/64.

Contrary to expectactions, allowed IID==64 for 464xlat should not mean
that plen==65 in RA is prohibited.

(I now realize that because 64 is precisely half of 128 we actually have
two problems: default plens at 64 and also default IIDs at 64.)

Alex