Re: [6lo] Generation of IPv6 IIDs

["Jonathan Hui (johui)" <[e-mail]>]

[Sorry for the dup.  The 6lo mailer is complaining that there’s too many recipients.]

On Jul 24, 2014, at 10:43 AM, Fernando Gont <[e-mail]> wrote:

> On 07/24/2014 01:17 PM, Kerry Lynn wrote:
>>> I think we should assume that those documents will be updated in
>>    the future to provide the option to work with other IIDs even if
>>    that comes with lower efficiency.
>> 
>>    Note that RFC 6282 already provides the option:
>>    - If the IID can be derived from MAC address, great.
>>    - If not, things will still work just with reduced efficiency.
>> 
>> To recap, re-using the L2 addresses for IIDs contributes to the
>> efficiency of
>> IPHC [RFC 6282].  Using locally-assigned short MACs provides the greatest
>> efficiency.
> 
> I'd personally say that sticking to MAC-derived IIDs is not a good idea.
> It's okay if that's still employed before something else is engineered,
> though.

Can you elaborate more?  As mentioned before, the scope of 802.15.4 Short Addresses is the PAN.

>> Requiring randomly assigned IIDs can have a significant impact on 6lo
>> networks
>> with short frames, which already have reduced payloads due to security
>> and other
>> headers.  In some cases, random IIDs might necessitate an additional
>> frame per
>> message.
>> 
>> 
>>    Section 10 of RFC 4944 also provides the same option, but has since
>>    been replaced by the encoding specified in RFC 6282.
>> 
>>    Also note that 802.15.4 interfaces have both a stable MAC address
>>    (EUI-64) and a locally-significant, dynamic MAC address (Short
>>    Address).  Many of the arguments against MAC-address-based IIDs may
>>    not apply when using Short Addresses.
>> 
>> I'm not sure that any of the arguments do apply when using locally assigned
>> short MAC addresses.  Please note that draft-ietf-6lo-6lobac *only* uses
>> locally
>> assigned short MAC addresses.
> 
> If you generate your IIDs from a constant IID, they do apply. Please see
> e.g.
> <http://tools.ietf.org/id/draft-ietf-6man-ipv6-address-generation-privacy-01.txt>
> for a longer version of the story.

I assume you meant “constant MAC address”.  In any case, see my comment above.

—
Jonathan Hui