Re: Confirmation to advance: draft-ietf-6man-ipv6only-flag-05

[Philip Homburg <[e-mail]>]

>If I understand correctly, you were arguing that IPv4 SD should be
>disabled by default for IPv6 only networks.

>For the average user, this means that if they actually needed, now they
>are in trouble.

Not really. It just means that you need to have a DHCPv4 server if you want
to use IPv4. Whether a CPE ships with DHCPv4 enabled by default can change
over time.

Or to put it in other words, IPv4 SD would only work if supported by DHCPv4.

>What saves headaches is to not disable functionality. At the end of the
>day, I wonder the extent to which a few IPv4 packets affect battery on a
>normal network as opposed to multiple 200MB+ apps  that drain the CPU
>for even the most trivial stuff, continuous wake up do to online
>presence apps, etc.

It is more than just a bit of SD. I think some (most? all?) stacks assume
that all of IPv4 is onlink when they have an IPv4 link local. So any A
record returned in DNS may trigger ARP traffic for that address. That
requires all applications to deal with broken IPv4.

>And no, it's not just the printer. a bunch of the smart devices you can
>connect at home (cameras, smart plugs, sensors, etc.) are still IPv4
>only. An "IPv6-only network" will just break all that.

What about running a DHCPv4 server to support those devices? 

>If you *don't want IPv4*, you filter at layer 2. Otherwise you're mostly
>advising your network on the intent.  But nodes are free to communicate
>over ipv4 if they wish.

That is true. But most of networking is based on cooperation not on 
enforcement. Describing intent is important.

>auto-linklocal is, in a sense, -- and by definition --  a kind of
>anarchy. Such "anarchy" has proven valuable, both when the network
>fails, or there are issues with the infrastructure (or there is no
>infrastructure).

In the case of working IPv6 the network is in some sense managed. From a
host (and user) perspective is more clear if the network is actually treated
as managed, and not as half managed (IPv6), half chaos (IPv4).