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

[Alexandre Petrescu <[e-mail]>]

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.
>