[PATCH v2] dhcp6c: DHCPv6 client

[Denys Vlasenko]

On Monday 07 November 2011 19:57, Leonid Lisovskiy wrote:
> On Mon, Nov 7, 2011 at 10:23 PM, Denys Vlasenko
> <vda.linux at googlemail.com> wrote:
> >>>
> >>>> One upstream(listen) interface - yes. But simplification to single
> >>>> downstream (IA, PD) interface seems to be bad idea.
> >>>
> >>> Can you elaborate why is it a bad idea?
> >>
> >> Of course, yes. For a example, take linux(busybox)-based CPE -
> >> router/gateway/access point. It has at least two interfaces - WAN &
> >> LAN. In case of DHCPv6 used by ISP to provide IPv6 access, we have to:
> >>
> >> 1) assign address(IA) on WAN interface
> >> 2) assing prefix(PD) on LAN interface
> >>
> >> Thus, we must support two interfaces, at least.
> >
> > This does not explain the problem for me.
> > You have two interfaces? No problem: run two udchpc6's,
> > one per interface.
> 
> We must issue request/renew/release _both_ IA/PD queries on WAN
> interface(which connects to ISP equipment). LAN connected to customer
> equipment only. Any broadcast/multicast queries on LAN interface will
> never rich ISP without special ip(6)tables rules.

Hmm. Can you describe in detail what is in the packet which client sends
to server in Solicit packet? What options (with nested suboptions)?


> For IPv4 scheme was simple - udhcpc client assign address on WAN, LAN
> has predefined private addresses (192.168.0.0/24). Customers works via
> NAT.
> 
> For IPv6 similar scheme don't work - we hasn't private addresses at
> all. ISP must give our CPE /128 address + /64 prefix, at least. And
> this info can be in single DHCPv6 packet.

There are tons of things which you might want to configure
on the device - LAN's IPv6 address is not the only one.
Such as, I don't know, default color of web interface
shown to user.
Let's pass it through DHCP too, why not?
And also lets download firmware updates over it.
This makes about as much sense as setting eth1's prefix
over DHCP on eth0.

-- 
vda