Re: [v6ops] draft-ietf-v6ops-64share

[Cameron Byrne <[e-mail]>]

Mark,

Sent from ipv6-only Android
On Jan 20, 2013 3:31 AM, "Mark Smith" <[e-mail]> wrote:
>
> Hi,
>
>
> >________________________________
> > From: Cameron Byrne <[e-mail]>
> >To: [e-mail]
> >Sent: Sunday, 20 January 2013 12:23 PM
> >Subject: [v6ops] draft-ietf-v6ops-64share
> >
> >
> >Hi,
> >I posted this update as a WG draft
> >http://tools.ietf.org/html/draft-ietf-v6ops-64share-00
> >Please take the time to review this update and share your feedback.  I
hoping that a clearly defined scope, clear need for this work,  as well
running code will make it easy to advance. I am now aware of 3
implementations that approximately use this method (ios6, an LTE mifi
router, and Dan Drown's Android submission)
>
> Regarding this text,
>
>  9.  Since the address 2001:db8:ac10:f002:1234:4567:0:9/128 is the
>        only instance of the assigned /64 on the 3GPP interface, there is
>        no chance of an address conflict on that interface.  On the LAN
>        interface, there is no chance of address conflict since the
>
>
>
> Byrne                    Expires June 17, 2013                  [Page 4]
>
> V6OPS Working Group   draft-ietf-v6ops-64share-00      December 14, 2012
>
>
>        address is defended using Duplicate Address Detection (DAD).
>
> I'd suggest adding something like "address is defended using Duplicate
Address Detection (DAD), as the LAN interface is also assigned the address
in use on the 3GPP interface."
>
> I struggled a bit with working out what was going on until it became
clear that the 3GPP and LAN interfaces are using the same global unicast
address.
>

The DAD procedure on the LAN is only scoped for the LAN. For the 3gpp link,
it is the fact that only 1 off-link address is architecturally permitted by
3gpp that ensures no collision.

Did I parse your concern correctly?

> I also think it would be better to be clearer about the type of IPv6
address and also cover that their may be multiple IPv6 addresses, such as
privacy addresses on the 3GPP/LAN interface. For example, in 3. Method for
Sharing the 3GPP Interface /64 to the Tethered LAN,
>
> "The UE checks to make sure the 3GPP interfaces is active and has
>        an IPv6 address.  If the interface does not have an IPv6 address,
>        an attempt will be made to acquire one, or else the procedure
>        will terminate."
>
> Strictly, the 3GPP interface always has an IPv6 address because it always
has a link local address, so the above would be better if it clarified that
the type of address to check for is a global IPv6 address.
>

Ack. I will change it to "globally scoped address"

> I'll have to do some digging, however I'm wondering if the sockets API
might have an assumption that an individual IPv6 address is only assigned
to a single interface.
>
> Actually, reviewing the IPv6 Addressing Model in RFC4291, it says, "An
IPv6 unicast address refers to a single interface."
>
> Was a translational bridge model considered? That is, the 3GPP and LAN
interfaces are part of a bridge instance, and a single bridge virtual layer
2/3 interface is assigned the UE's global unicast address within the /64,
with a /64 prefix length. Enabling or disabling tethering would be a simple
matter of administratively enabling/disabling the LAN interface.
>

Is there an ietf doc on what a translational bridge is? We considered
ndproxy but that method was deemed unfit due to insufficient loop
prevention.

CB

> Regards,
> Mark.