Re: [v6ops] RFC6459 "IPv6 in 3GPP" - the IID in the LL address and GUA

[Alexandre Petrescu <[e-mail]>]

Le 12/07/2017 à 14:02, [e-mail] a écrit :
> Alex,
> 
> The key part is not to use (or not) a GUA, but ...
> 
> The GGSN shall not generate any globally unique IPv6 addresses for
> itself using the Prefix assigned to the MS in the Router
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Advertisement.

If it is not the GGSN then who does it?

The UE receives an RA with a GUA in its SRC; packet dump available upon 
request.

Alex

> 
> Cheers,
> Med
> 
>> -----Message d'origine-----
>> De : Alexandre Petrescu [mailto:[e-mail]]
>> Envoyé : mercredi 12 juillet 2017 13:42
>> À : BOUCADAIR Mohamed IMT/OLN; [e-mail]
>> Objet : Re: [v6ops] RFC6459 "IPv6 in 3GPP" - the IID in the LL address and
>> GUA
>>
>> Med,
>>
>> [...]
>>>>>>> Further, a network does not need IP-related information to
>>>>>>> identify an UE.
>>>>>>
>>>>>> I agree, so why does it want to impose an IID to the UE?
>>>>>
>>>>> [Med] This is an optimization to avoid DAD.
>>>>
>>>> Ok about LL, but how about the GUA?
>>>
>>> [Med] No problem at that front either (reading from the 3GPP spec):
>>>
>>> == Since the GGSN guarantees that the Prefix is unique, the MS does
>>> not need to perform any Duplicate Address Detection on addresses it
>>> creates. ==
>>   >
>>>
>>> If the network uses a GUA same as
>>>> the UE then there should be DAD for that GUA.
>>>
>>> [Med] Idem as above, the spec is clear:
>>>
>>> == The GGSN shall not generate any globally unique IPv6 addresses for
>>> itself using the Prefix assigned to the MS in the Router
>>> Advertisement. ==
>>
>> I think that spec is wrong (3GPP TS. 29.061?).
>>
>> Because, in practice some operator on some APN puts a GUA (not an LLA)
>> on its router's interface towards the UE.  It uses that GUA in the src
>> of the RA sent to the UE.  Packet dump available upon request.
>>
>> Alex
>>
>>>
>>>>
>>>> I dont think there is any spec that tells that the network MUST
>>>> NOT assign a GUA on its interface towards the UE.
>>>
>>> [Med] See for example, 3GPP TS. 29.061
>>>
>>>>
>>>>
>>>>
>>>>>>> I still don't see any privacy concern in supplying an IID to
>>>>>>> an UE to be used for forming its link-local address.
>>>>>>
>>>>>> Err...
>>>>>>
>>>>>> It's because the supplied IID is very much like an IEEE MAC
>>>>>> 48bit address.
>>>>>
>>>>> [Med] This is a link-local address not a GUA. So, not sure to
>>>>> understand
>>>> your point.
>>>>
>>>> I can understand your point about GUA privacy vs LL privacy.
>>>
>>> [Med] OK.
>>>