RE: new draft on IPv6 CPE router available for review

["teemu.savolainen@nokia.com" <teemu.savolainen@nokia.com>]

>> I'm not sure if the GGSN even configures itself global address from 
>> the prefixes it gives to subscribers (does router have to 
>configure an 
>> address for itself from the prefixes it sends out in RAs?). I was 
>> unable to verify this right now.
>
>No, that requirement went the way of the dodos in IPv6.
>
>Does this system give the subscriber more than just one /64? 
>If not, the phone needs to be a bridge and the service 
>provider will see more individual addresses.

Currently just one /64 per bearer. However, a network provider may
configure phones to use simultaneously more than one bearer (called PDP
contexts or EPS bearers as per 3GPP Release-8). A network provider can
choose to configure separate bearers to be used for Internet and
Intranet accesses. E.g. browser application may be configured to use
bearer that provides only Internet connectivity, while email application
may be configured to use bearer that can be used only to access
Intranet.

There are discussions ongoing about making it possible for phones to get
more prefixes with DHCPv6 PD.

As far as I see, future cellular system could work like this:
- allocate single /64 per bearer (as now)
- phone uses SLAAC to configure an address for itself from this prefix
(as now)
- phone checks (or is preconfigured with required information) whether
the recently attached network supports DHCPv6 PD
-> if YES
	- phone gets more prefixes with DHCPv6 PD, and starts to
advertise them to LAN
-> if NO
	- phone engages ND Proxy

This also gives implementation priority for phones that wish to share
the single "WAN" bearer with other devices: ND proxy support is a must,
while DHCPv6 PD is a should as it is not guaranteed to be available in
all networks the phone may connect to.

This approach has the benefit of using just single bearer between phone
and cellular network, which saves network's resources (when compared to
multiple parallel bearers).

Alternative implementation is to have multiple bearers (=multiple WAN
connections), e.g. one bearer for phone's internal applications, and
different bearer for LAN use. In this approach network allocates one /64
for the phone's own use, and another /64 for the LAN's use (which can be
implemented as a standard dial-up modem like functionality, or as a
bridging solution).

The multiple bearer solution works however only in certain cellular
environments, as there is also a case where a phone is providing IP
connectivity to Bluetooth Personal Area Network: when connected to
cellular network, the phone may have one or more bearers with DHCPv6 PD
or not, but if the phone happens to connect to WLAN hot-spot, it has not
other option than to share the WLAN connection between the internal
applications and the Bluetooth PAN network.

Best regards,

	Teemu