Re: [dhcwg] Informational IPv6 prefix option for DHCPv6

Hi Andre,

> -----Original Message-----
> From: Andre Kostur [mailto:akostur@incognito.com]
> Sent: Monday, July 07, 2014 12:27 PM
> To: Templin, Fred L
> Cc: dhcwg@ietf.org
> Subject: Re: [dhcwg] Informational IPv6 prefix option for DHCPv6
> 
> Then I'm not sure of the purpose of this information.  The client got
> an IPv6 address from somewhere, so it should be able to know its
> prefix from that.  What's the client supposed to do with this
> information that it's getting from DHCP?

It is for a link type on which there is no non-link-local IPv6 prefix
assigned. The link connects a bunch of routers that only configure a
link-local address on the link. The routers also act as DHCPv6 clients,
and act as requesting routers using DHCPv6 PD to get a prefix to assign
to their downstream attached links.

The IPv6 prefix I want to include in the DHCPv6 option I am asking for
is the aggregated prefix from which client prefixes are delegated. So,
if the aggregated prefix is 2001:db8::/32, then the clients would be
delegated longer prefixes such as 2001:db8:4000::/48, 2001:db8:1::/56,
2001:db8:21:31::/64, etc.

So, the aggregated prefix is not assigned *to* the link, but rather
tells the set of prefixes that can be reached *through* the link.
This is important information that I want to provide to the clients
via a DHCPv6 option.

Thanks - Fred
fred.l.templin@boeing.com

> On Mon, Jul 7, 2014 at 11:52 AM, Templin, Fred L
> <Fred.L.Templin@boeing.com> wrote:
> > Hi Andre,
> >
> > No, this is not Prefix Delegation. For PD, the DHCPv6 server
> > returns an IPv6 prefix that the client then uses to number its
> > downstream-attached links. What I want is an informational
> > option that pertains to the link over which the client contacts
> > the server, and to my understanding PD cannot be used for that.
> >
> > Thanks - Fred
> > fred.l.templin@boeing.com
> >
> >> -----Original Message-----
> >> From: Andre Kostur [mailto:akostur@incognito.com]
> >> Sent: Monday, July 07, 2014 11:23 AM
> >> To: Templin, Fred L
> >> Cc: dhcwg@ietf.org
> >> Subject: Re: [dhcwg] Informational IPv6 prefix option for DHCPv6
> >>
> >> Isn't that Prefix Delegation? RFC 3633.  Nutshell is that the client
> >> can specifically ask the server for a prefix.  Part of the plan is for
> >> routers deployed out at the edge, and they can ask the DHCP server for
> >> a prefix that the router will then manage on its further downstream
> >> links.
> >>
> >> On Mon, Jul 7, 2014 at 10:54 AM, Templin, Fred L
> >> <Fred.L.Templin@boeing.com> wrote:
> >> > Hi,
> >> >
> >> > I am looking for a DHCPv6 option that a server can use to report an IPv6
> >> > prefix to a client. This *would not* be used as a replacement for Router
> >> > Advertisement Prefix Information Options (PIOs), and the client *would
> >> > not* use the prefix for SLAAC.
> >> >
> >> > A DHCPv6 option that specifically returned an IPv6 prefix (along with
> >> > prefix length) would be preferred. A DHCPv6 option that returned opaque
> >> > data could also be used as a kludge but I would rather not have to do
> >> > that. Is there a DHCPv6 option that would meet these requirements?
> >> >
> >> > Thanks - Fred
> >> > fred.l.templin@boeing.com
> >> >
> >> > _______________________________________________
> >> > dhcwg mailing list
> >> > dhcwg@ietf.org
> >> > https://www.ietf.org/mailman/listinfo/dhcwg
> >>
> >>
> >>
> >> --
> >> Andre Kostur
> 
> --
> Andre Kostur