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

[Philip Homburg <[e-mail]>]

>In my opinion, you are correct if that were the only or even the primary
>source of futile IPv4 traffic. In effect, RFC 3927 configures a Link-Local
>IPv4 scoped address if a DHCPOFFER is not received, and then this
>Link-Local address is used to perform futile IPv4 service discovery. From
>my perspective, this is the primary problem, not futile IPv4 DHCPDISCOVERS.
>As you say exponential backoff of the DHCPDISCOVERS would easily control
>that issue. However, something also needs to signal the dual-stack host to
>not perform IPv4 service discovery because the dual-stack host is on an
>IPv6-Only network, I believe this flag serves this purpose well.

It is safe to assume that if an interface has no IPv4 address
configured at all then that interface cannot be used for IPv4 service
discovery

We can assume that on an IPv6-only network there will be no DHCPv4 so the
host will not get addresses through that route.

That leaves RFC 3927. I think a simple heurisctic could be the following:
A host SHOULD NOT configure an RFC 3927 on an interface if the host has
working IPv6 on that interface unless the configuration of an IPv4 link local
address is explicitly requested by the user.