Re: [dhcwg] Iotdir last call review of draft-ietf-dhc-v6only-03

["Eric Vyncke (evyncke)" <[e-mail]>]

Thank you Pascal for your extensive review.

-éric

-----Original Message-----
From: Pascal Thubert via Datatracker <[e-mail]>
Reply-To: Pascal Thubert <[e-mail]>
Date: Tuesday, 23 June 2020 at 11:55
To: "[e-mail]" <[e-mail]>
Cc: "[e-mail]" <[e-mail]>, "[e-mail]" <[e-mail]>, "[e-mail]" <[e-mail]>
Subject: Iotdir last call review of draft-ietf-dhc-v6only-03
Resent-From: <[e-mail]>
Resent-To: Lorenzo Colitti <[e-mail]>, <[e-mail]>, <[e-mail]>, <[e-mail]>, <[e-mail]>, <[e-mail]>, Eric Vyncke <[e-mail]>, <[e-mail]>, Bernie Volz <[e-mail]>
Resent-Date: Tuesday, 23 June 2020 at 11:55

    Reviewer: Pascal Thubert
    Review result: Ready with Issues

    draft-ietf-dhc-v6only-03 IOT-DIR review
    _______________________________________

       This document specifies a DHCPv4 option to indicate that a host
       supports an IPv6-only mode and willing to forgo obtaining an IPv4
       address if the network provides IPv6 connectivity. It is very readable
       and provides a clear justification of why the DHCP-based solution is
       well suited to address the problem.



       "
                                                 ... IPv6-only mode (either
       because the OS and all applications are IPv6-only capable or because
       the host has some form of 464XLAT [RFC6877] deployed),
       "
       Do we have a good reference of what we mean by the v6-only mode of a host
       - or an interface for that matter ?

       Else it would help to define it before we use it. Note, the terminology
       defines a "IPv6-only capable host" but not the "mode".




       "
       A DHCPv4 client SHOULD allow a device administrator to configure
       IPv6-only preferred mode
       "
       and later
       "
                                     In a typical deployment scenario, a
       network administrator would not configure the DHCPv4 server to return
       the IPv6-only Preferred option unless the network provides NAT64
       service.

       ...

       However it seems unlikely that any new transition technology would
       arise and be widely adopted in any foreseeable future.  Therefore
       adding support for non-existing technologies seems to be suboptimal
       and the proposed mechanism implies that NAT64 is used to facilitate
       connectivity between IPv6 and IPv4.
       "

       I have a hard time with that one. Adding a byte or 2 of flags in the
       IPv6-Only Preferred option to indicate that the network supports NAT64
       and having the host request the address if it needs the service and it's not
       there does not seem to cost a lot and protects the future.