Re: Updated IID length text

Fernando Gont <fgont@si6networks.com> Thu, 19 January 2017 04:20 UTC

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Subject: Re: Updated IID length text
To: Lorenzo Colitti <lorenzo@google.com>
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From: Fernando Gont <fgont@si6networks.com>
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On 01/19/2017 01:12 AM, Lorenzo Colitti wrote:
> On Thu, Jan 19, 2017 at 12:51 PM, Fernando Gont <fgont@si6networks.com
> <mailto:fgont@si6networks.com>> wrote:
> 
>     Oh, I love this. So you are a fan of still doing modified EUI-64 with
>     randomized MAC addresses (which wastes 18 bits, including the 16 bits
>     that are wasted with embedding 0xfffe), and now you say that using /48
>     would impact things substantially?
> 
>     This can't possibly make sense.
> 
> 
> It does make sense. /48 does impact things substantially. However, on
> like like wifi, the MAC address is the endpoint identifier, so if
> there's a duplicate MAC you can't get on the network.

Could you please explain how you do the math such that in these two
scenarios:

#1: SLAAC with 48-bit IIDs, where the IID is a random string of bits
    (e.g. as resulting from RFC7217)

#2: Traditional SLAAC with 64-bit IIDs, where the IID is generated from
    a randomized MAC address (and in which, based on how MOdified EUI64
    IIDs are generated, you have to embed the fixed 16-bit word 0xfffe
    in the IID)


..you get a reduced IID collision rate with #2?

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