Re: [v6ops] [EXTERNAL] Re: Next step? [Re: The bottom is /112]

[Mark Smith <[e-mail]>]

On Mon, 23 Nov 2020, 01:59 Templin (US), Fred L, <[e-mail]>
wrote:

> Hi, I believe the AERO/OMNI approach to prefix delegation would be good
> for the 3GPP
> case also. The approach is predicated on the router returning an RA with
> an IPv6 link-local
> destination address determined by the delegated prefix. The link-local
> address is formed
> by writing the most significant 64 bits of the delegated prefix into the
> interface ID of the
> prefix fe80::/64.


> For example, if the delegated prefix were 2001:db8:1:0::/56 then the IPv6
> link-local
> destination address is fe80::2001:db8:1:0. This provides at least two
> important
> operational advantages.
>
> 1) It conveys the delegated prefix in the IPv6 destination address of the
> RA so that
> no PIOs inside the RA need to be used for prefix delegation.
>

In my operational experience it is far better to make things explicit in
packets rather than implicit.

See RFC8469 for an example of where what was implicit in packets has caused
so many problems that now being explicit has become the recommendation.
(Absence of this in a wholesaler's network caused us and a customer months
of troubleshooting for unusual performance problems, and is now costing us
service outages for many customers at once while they put it in place.)



> 2) It supplies the mobile node with a guaranteed-unique link-local address
> that
> it can use for future communications without the need to perform DAD.



So the RA DA is carries both delegated prefix information and with
link-local address configuration too? How does a node know to use the RA DA
as its link-local address?

With the rise of wireless we need to care about the global traceability of
link-local addresses too. Persistent, globally unique link-local IIDs have
the same privacy implications as persistent globally unique WiFi MAC
addresses and Bluetooth MAC addresses.

Have a look at https://wigle.net and the Android app for collecting the
data.

A similar app focused on Bluetooth is Ramble.

Neither of these apps require a hacked phone, the can just be installed and
run by anybody from the Google app store.


> Again, the proposal comes from the AERO/OMNI use case, but I believe is
> also
> good for 3GPP and really any other wireless use case where a lightweight
> prefix delegation capability is desired.
>
> Fred
>