Re: Review of draft-ietf-6man-rfc4291bis-06
Fernando Gont <fgont@si6networks.com> Fri, 13 January 2017 21:02 UTC
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Subject: Re: Review of draft-ietf-6man-rfc4291bis-06
To: Brian E Carpenter <brian.e.carpenter@gmail.com>, Randy Bush <randy@psg.com>
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From: Fernando Gont <fgont@si6networks.com>
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Date: Fri, 13 Jan 2017 17:59:45 -0300
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Cc: Bob Hinden <bob.hinden@gmail.com>, IETF <ietf@ietf.org>, IPv6 List <ipv6@ietf.org>, draft-ietf-6man-rfc4291bis.all@ietf.org, int-dir@ietf.org
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On 01/13/2017 04:58 PM, Brian E Carpenter wrote: > > On 14/01/2017 08:44, Fernando Gont wrote: >> On 01/12/2017 10:55 PM, Brian E Carpenter wrote: >>> On 13/01/2017 13:50, Randy Bush wrote: >>>>> RFC7421 (which is Informational) calls out RFC 6164 (not 6141!) as an exception. >>>>> To be precise it says: >>>>> >>>>> The de facto length of almost all IPv6 interface identifiers is >>>>> therefore 64 bits. The only documented exception is in [RFC6164], >>>>> which standardizes 127-bit prefixes for point-to-point links between >>>>> routers, among other things, to avoid a loop condition known as the >>>>> ping-pong problem. >>>>> >>>>> I would suggest adding a similar exception statement in 4291bis. >>>> >>>> and then next year we will go through another draft and have another >>>> exception. just get rid of classful addressing. we went through this >>>> in the '90s. >>> >>> The problem is (and why we wrote 7421) is that stuff breaks with subnet >>> prefixes longer than 64, *except* for the point-to-point case covered >>> by 6164. Yes, I see the problem in enshrining this but I think we face >>> signifcant issues if we do otherwise. >>> >>> What we could conceivably say is that /64 is mandatory except for >>> links where SLAAC will never be used. (SLAAC itself is designed >>> to work with any reasonable length of IID, but again in practice it >>> only works with /64, because we need mix-and-match capability. So >>> although IID length is a parameter in the SLAAC design, it's a >>> parameter whose value needs to be fixed globally.) >> >> Well, yes and no. With the traditional slaac (embed the mac address) it >> only works with 64-bit IIDs. With something like RFC7217 (grab as many >> bits as needed to for an IID), it could work. > > Technically that's true, but you can't mix IID sizes on a given link > and expect it to work, so any legacy system will force the whole link > to use /64. Well, you could say that you don't need to mix IID sizes on the same link: the IID size is whatever the local router happens to advertise (i.e., 128-Prefix_Length). And, if you do manual configuration, you're supposed to know the prefix length... -- Fernando Gont SI6 Networks e-mail: fgont@si6networks.com PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
- Review of draft-ietf-6man-rfc4291bis-06 Brian Haberman
- Re: Review of draft-ietf-6man-rfc4291bis-06 Bob Hinden
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 Punana Lebo
- Re: Review of draft-ietf-6man-rfc4291bis-06 Brian Haberman
- Re: Review of draft-ietf-6man-rfc4291bis-06 Bob Hinden
- Re: Review of draft-ietf-6man-rfc4291bis-06 Bob Hinden
- Re: Review of draft-ietf-6man-rfc4291bis-06 Bob Hinden
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 Brian E Carpenter
- Re: Review of draft-ietf-6man-rfc4291bis-06 David Farmer
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 Brian E Carpenter
- Re: Review of draft-ietf-6man-rfc4291bis-06 Lorenzo Colitti
- Re: Review of draft-ietf-6man-rfc4291bis-06 heasley
- Re: Review of draft-ietf-6man-rfc4291bis-06 Suresh Krishnan
- AW: Review of draft-ietf-6man-rfc4291bis-06 Karsten Thomann
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 sthaug
- Re: Review of draft-ietf-6man-rfc4291bis-06 Lorenzo Colitti
- Re: Review of draft-ietf-6man-rfc4291bis-06 Randy Bush
- Re: Review of draft-ietf-6man-rfc4291bis-06 Lorenzo Colitti
- Re: AW: Review of draft-ietf-6man-rfc4291bis-06 Brian E Carpenter
- Re: Review of draft-ietf-6man-rfc4291bis-06 Fernando Gont
- Re: Review of draft-ietf-6man-rfc4291bis-06 Fernando Gont
- Re: Review of draft-ietf-6man-rfc4291bis-06 Brian E Carpenter
- Re: Review of draft-ietf-6man-rfc4291bis-06 heasley
- Re: Review of draft-ietf-6man-rfc4291bis-06 Mark Smith
- Re: Review of draft-ietf-6man-rfc4291bis-06 Fernando Gont
- Re: Review of draft-ietf-6man-rfc4291bis-06 John C Klensin
- Re: Review of draft-ietf-6man-rfc4291bis-06 Brian E Carpenter
- Re: Review of draft-ietf-6man-rfc4291bis-06 David Farmer
- Re: Review of draft-ietf-6man-rfc4291bis-06 Mark Smith
- Re: Review of draft-ietf-6man-rfc4291bis-06 Brian E Carpenter
- Re: Review of draft-ietf-6man-rfc4291bis-06 Lorenzo Colitti