RE: Stateless Prefix Delegation I-D updated (draft-savolainen-stateless-pd)

[<teemu.savolainen@nokia.com>]

Hi,

> In theory what you propose should work, but...
> 
> Let's assume we assign 2001:db8:1:200::/56 to the device.
> 
> It would give the uplink 2001:db8:1:200::/64 and say

Actually the network (AC) would advertise to the device's uplink that prefix, not the device.

> However the Access Concentrator has to deal with a paradoxical
> situation:
> several overlapping routes. If we assume the AC has host-ID ::1 and the
> CPE device or mobile phone has ::2:
> 
> 2001:db8:1:200::1/128 loops back to the AC(*)
> 2001:db8:1:200::/64 has the link as direct target without gateway
> 2001:db8:1:200::/56 goes to gateway fe80::2 via the same link

Mikael commented the longest matching prefix point, so why it wouldn't work? (From point-to-point link (PPP) point of view, the AC just needs to send all packets matching to /56 to the peer except the address it has possibly configured to its end).
 
> It may work or it may not work. The alternative is a lot more entries
> in the routing table.

Hmm.. but that problem is perhaps a problem only for the AC, right? I mean for all provisioning, policy and charging (PCC) etc entities it is just single /56 that needs to be considered per subscription, not a /56 and a /64?

> What I described below has the upside that the third route does not
> overlap with the others. It has of course the downside that it uses up
> slightly more address space.

.. and that PCC needs to consider both /56 and /64 for a single subscription, whileas in the alternative PCC has to consider only single /56.

Best regards,

Teemu