extending at the edge

Gert Doering gert at space.net
Wed Oct 10 17:11:27 CEST 2012


On Wed, Oct 10, 2012 at 04:05:53PM +0100, Tony Finch wrote:
> Nick Hilliard <nick at foobar.org> wrote:
> > On 10/10/2012 15:58, Tony Finch wrote:
> > > If I have a device with an IPv6 connection, how do I share that connection
> > > with other devices? With IPv4 I would use NAT. What is the answer for IPv6?
> >
> > the expected edge configuration is that you get one or more /64 subnets
> > routed down to you.
> Is that true for cellular connections? IME with ethernet I have to share a
> /64 with other users' devices, so to share my connection I would either
> have to NAT or do layer 2 bridging. I guess wifi would be somewhat
> similar, though I wonder how well that would work with 802.1x.

Cellular says "each device gets a /64 on its own", so the usual suspects
use that /64 for LAN *and* WAN (by device-specific approaches, long
discussion on IETF v6ops list recently).

The WAN side in cellular is not "ethernet", it is point-to-point tunnels
through the 3G/LTE network, so you do not really have a "LAN" there - you
have one address on the terminal, and "a default route pointing into that
tube".  While the other send sends the whole /64 "through the tube" and
doesn't care what you do with it (because it cannot see it anyway).

Wifi depends on "who offers it" - in DSL- or Cable-Networks, the 
approach people seem to agree on is

  - RA/SLAAC for assigning a single IPv6 address to the WAN side of the router

  - DHCP-PD for delegating a /56 ("something useful") to the router, for 
    use on the LAN side.  Whether that is a /56 or /48 or /60 depends on the
    ISP, but "/56" seems to be some sort of common ground for home.

Gert Doering
        -- NetMaster
have you enabled IPv6 on something today...?

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