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Re: [v6ops] WGLC: draft-ietf-v6ops-unique-ipv6-prefix-per-host-02 - multiple prefixes per device

Fernando Gont <fgont@si6networks.com> Fri, 17 March 2017 21:04 UTC

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To: Brian E Carpenter <brian.e.carpenter@gmail.com>, Gert Doering <gert@space.net>
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Cc: v6ops@ietf.org
From: Fernando Gont <fgont@si6networks.com>
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Subject: Re: [v6ops] WGLC: draft-ietf-v6ops-unique-ipv6-prefix-per-host-02 - multiple prefixes per device
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On 03/16/2017 07:43 PM, Brian E Carpenter wrote:
> On 17/03/2017 09:14, Gert Doering wrote:
>> Hi,
>>
>> On Fri, Mar 17, 2017 at 06:31:43AM +1300, Brian E Carpenter wrote:
>>> So, it seems clear to me that while getting a /64 is better than getting
>>> a /128, it's even better to get a /56. Or even one of those 15 trillion /48s.
>>> We should make it clear that /64 is not even second-best. Just better
>>> than /128.
>>
>> "give any *host* that connects a /48" (and dimension pools on WiFi
>> hotspots etc. big enough to actually be able to do this) might actually 
>> be a good way to ensure IPv6 is going to run out faster than expected...
>>
>> IOW, be careful with the maths here.
> 
> Yes, one always needs cautious allocation policies. But still... /64
> is not enough in the general case, with today's link-layer media
> and today's IPv6 stacks. (We can have the argument about tomorrow
> some other time. :-)

Well... /64 is not enough because somehow we choose to waste a large
part of 128-64. IN principle if one were to use 48 bits for the iid (or
even 56) that would still be big enough for randomizing IID, while still
having 16 or 8 bits for "subnetting"...

Cheers,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492

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