b10-dhcp6 doesn't not bind on Scope:Global inet6 address.

[Tomek Mrugalski]

On 14.03.2014, 13:15, Angelo Failla wrote:
> On a side note I think you guys should make the v6 server binding by
> default to ALL configured v6 addresses…
> At least just to make it consistent with the way the v4 server works.
> The decision is on you, just providing some user feedback :)
It was a design decision influenced by couple facts.

The first one is that it that binding a global unicast address is almost
equal to enabling server unicast by default. What whould we do if
clients start sending traffic to that unicast address? Should we drop
it, even though we received the message (that's what RFC3315 tells us)?

The other more fundamental reason is that some people do not want their
server to listen on all possible interfaces. There are valid reasons
where you want to listen only on specific interface or on specific
address on that interface (e.g. you can have multiple global addresses
and one of them is reserved for DHCP use, so you can filter the traffic
more conveniently).

Also think about more dynamic setups. What if you have a system that has
temporary (like ppp) interfaces that occasionally go up? Should the Kea
server bind to it immediately (as soon as it detects new interface)?
Should it periodically detect if there are any new global addresses
appearing on already configured interfaces? These are tricky questions
without any clear best answers. So we decided to be conservative. If the
server listens on something, administrator has to explicitly tell it to
listen.

It's a design choice, really. We can either not bind globals and provide
a way for users to tell what they want to bind or bind everything and
provide a way for users to tell what they don't want to bind. We chose
the former, because it is more conservative.

But of course that's not something carved in stone. It is possible to
consider adding a flag, something like "bind-all-globals" or
"bind-to-new-interfaces". But we don't have anything like this planned.

Hope that helps,
Tomek