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

["Bernie Volz (volz)" <[e-mail]>]

I’m somewhat fine with your text.

The “unless the CE Router implements [RFC7844].” seems like something one could drive a truck through? What part(s) of [RFC7844] are you talking about (perhaps the text in section 4.5 and referencing it might be best here). Perhaps, “unless the CE Router implements the IAID techniques discussed in Section 4.5 of [RFC7844].” (or something like that).


  *   Bernie

From: Fernando Gont <[e-mail]>
Date: Thursday, February 25, 2021 at 4:59 PM
To: Bernie Volz (volz) <[e-mail]>, Benjamin Kaduk <[e-mail]>, The IESG <[e-mail]>
Cc: [e-mail] <[e-mail]>, [e-mail] <[e-mail]>, [e-mail] <[e-mail]>, Owen DeLong <[e-mail]>
Subject: Re: Benjamin Kaduk's No Objection on draft-ietf-v6ops-cpe-slaac-renum-07: (with COMMENT)
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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