Re: [v6ops] Benjamin Kaduk's No Objection on draft-ietf-v6ops-cpe-slaac-renum-07: (with COMMENT)

[Fernando Gont <[e-mail]>]

On 25/2/21 18:09, Bernie Volz (volz) wrote:
> As DHCPv6 uses the DUID and IA Type (this is fixed based on what client wants - such as IA_PD) and IA_ID, a device should keep these consistent (across reboots, ...).
> 
> If the DUID changes, then there's no reason that the IA_ID cannot change (it's a different client).
> 
> If the DUID doesn't change, you MUST keep the IA_ID for a particular interface constant (I'm not sure I would tie this to the interface's link-layer address, but I guess you could).

My take is that this is a bit of a stretch in RFC7844.



> If a device changes the IA_ID (without changing the DUID), the problem is that the DHCPv6 server will think this is a "different" request than the earlier IA_ID and assign new prefixes or addresses (and no communication about previously used ones).
> 
> If the DUID changes, it is a different client anyway - so then the IA_ID can be a new value.

Thinking back about this: maybe it would be simpler to state something 
along the lines of:

       o  WPD-10: CE Routers MUST by default use a WAN-side IAID
          value that is stable between CE Router restarts, DHCPv6
          client restarts, or interface state changes (e.g., Transient
          PPP interfaces) unless the CE Router implements [RFC7844]. See
          Section 3.2 for further details.

?

Thanks!

Regards,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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