On 13 okt 2008, at 18:38, David W. Hankins wrote:
Seems to me that this is simple enough: no bits, no DHCP. "Always"
is not
an acceptable out of the box behavior. (!!!)
Why? It seems perfectly fine to me, since the Solicits follow an
exponential backoff.
See my earlier emails.
Further, it seems pretty clear to me that router
solicitation is on a long path towards deprecation,
Where do you see evidence for that? I haven't seen this.
And even if people wanted that, I don't think it's possible to get to
a situation without RAs from the current situation, where the majority
of systems _only_ understand RAs, apart from manual configuration.
as it is incomplete by design
Depends on your requirements. With RFC 5006 RAs provide everything you
need in an unmanaged / lightly managed network.
so having DHCPv6 operate by default seems to me
the best way to position current clients for the impending migration.
The important thing is that we don't just decide what WE think is best
but allow everyone to run their networks the way THEY want. Today,
many people do this without DHCPv6. Presumably, more people will want
to use DHCPv6 as implementations get better, but I don't see this ever
reaching 100%.
Then if there is M you do stateful DHCPv6, if there is O stateless.
The
only problem would be if bot O and M are set.
The other problem is when there is an A bit. Does M imply
revocation of
A? Some seem to think so; that A would only be set in this case for
backwards compatibility with clients that lack DHCPv6 stateful
support.
If you don't have such clients then you can set the A bit to 0 if you
want DHCP only so this is a reasonable line of thought but do you
really want to have three different types of hosts on your network:
- stateless autoconfig only
- stateless autoconfig + DHCPv6 (current implementations)
- DHCPv6 only
I'd say specify the desired behavior in a DHCPv6 option.
The other other problem is when there are two distinct routers, having
two distinct sets of prefixes (each representing a unique
administrative domain, what Joseph understands (rightly?) to be a
valid 'dual homing' setup), of which one, the other, or both are
advertising inconsistent bit values (especially the M&O bits).
You can have multiple DHCP servers, too.
The other other other...
There are problems...there are corner cases in the penumbra cast by
these "simple" designs' overlapping reach. They are not trivial, and
they are almost certainly misunderstood by most.
That's why it's necessary that the behavior is simple and predictable
but still flexible so that something reasonable happens in all cases.
The situation where multiple routers advertise multiple prefixes is
something that IPv6 supports, and stuff like easy renumbering and
shim6 even depend on it.
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