Re: Proposal to further clarify prefix length issues in I-D.ietf-6man-rfc4291bis

Mark Smith <markzzzsmith@gmail.com> Sat, 11 March 2017 12:52 UTC

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From: Mark Smith <markzzzsmith@gmail.com>
Date: Sat, 11 Mar 2017 23:51:49 +1100
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Subject: Re: Proposal to further clarify prefix length issues in I-D.ietf-6man-rfc4291bis
To: "Manfredi, Albert E" <albert.e.manfredi@boeing.com>
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On 10 March 2017 at 06:28, Manfredi, Albert E
<albert.e.manfredi@boeing.com> wrote:
> -----Original Message-----
> From: ipv6 [mailto:ipv6-bounces@ietf.org] On Behalf Of Philip Homburg
>
>> The first interface identifier concept is that for any prefix of
>> length n, the length of the interface identifier is 128-n. Let me
>> call this prefix-iid.
>>
>> The second iid concept is in auto configuration of addresses. I'll
>> call this slaac-iid.
>>
>> The way I see it, any slaac-iid that is based on (pseudo)-random
>> number has to be at least 64 bits. I don't see any reason for more
>> than 64 so exactly 64 sounds about right.
>
> If you want random, a PRNG can create any length of IID. A 48-bit IID would be just as reasonable, and it could be formed from a randomly changing link layer address.
>

You two have read

"Analysis of the 64-bit Boundary in IPv6 Addressing"
https://tools.ietf.org/html/rfc7421

haven't you?

48 bit IIDs were given up between RFC1883 and RFC2373.

<snip>

Regards,
Mark.