Choosing an open source DHCPv6 client

[Bjørn Mork]

Shane Kerr <shane at time-travellers.org> writes:

> Hm... our restrictions on interface support come mostly from the IPv4
> world. In that universe we have severe restrictions on what we can
> support because we have to do funky things to send & receive packets. In
> DHCPv6 one has the link-local addresses so one can use plain old
> application layer-UDP.

Yes, it's completely different.  Which is why I wondered if the combined
DHCP/DHCPv6 client is a good idea.  I can imagine that the timers/event
code could be reused, but that's about all.  IMHO.

> BUT... we do need to get the hardware address (a MAC address in the case
> of Ethernet) from the interface in DHCPv6. This address is needed to
> make the client identifier (in most cases). Unfortunately there is no
> standard way to do this - the API varies on each platform - and so we
> have to code up support everywhere. Clearly the code is showing its age,
> but it was written for the layer 2 stuff in use at the time. :)

I believe the requirements for a DHCPv6 DUID are specifically written to
allow DHCPv6 on any type of interface.

> It probably isn't a lot of work to extend this to support PPP, but since
> PPP generally does its own IP assignment, there hasn't really been much
> call for it.

For IPv4, sure.  DHCPv6 is just as interesting (if not more) on PPP as
it is on Ethernet.

We're probably going to require PPP for IPv6, at least in the beginning,
due to the L2 design we have between our BRAS's and the customers, and
the currently limited support for IPv6 based L2 magic.

And DHCPv6-PD is also going to be a requirement.  We might use SLAAC for
the WAN link, but we're not going to support SLAAC-only customers.  The
WAN prefix will most likely be filtered to allow management access
only.  The customers will have to select a source address from their
DHCPv6 delegated prefix to actually reach anything useful.

So PPP + DHCPv6-PD it is.

I'm quite sure we can't be the only ISP thinking like this...

> Do you mind if I forward this to the dhcp-users list? It's probably a
> better place for further discussion.

I don't mind, but I probably won't follow it.  The dhcp-users is is one
of the mailing lists I'm subscribed to, but rarely have time to read...

As with Gert, I'm really not that interested in DHCP (for IPv4)
discussions right now.  So maybe we can continue the DHCPv6-PD
discussion here as long as no-one complains about it being operational
off-topic?  My impression is that most IPv6 related topics are accepted
(and wanted?) here.



Bjørn