Re: [dhcwg] Informational IPv6 prefix option for DHCPv6

Hi Bernie,

> -----Original Message-----
> From: Bernie Volz (volz) [mailto:volz@cisco.com]
> Sent: Monday, July 07, 2014 1:15 PM
> To: Templin, Fred L; Andre Kostur
> Cc: dhcwg@ietf.org
> Subject: RE: [dhcwg] Informational IPv6 prefix option for DHCPv6
> 
> See http://tools.ietf.org/html/draft-sarikaya-dhc-dhcpv6-raoptions-sadr-00 as I this just got
> resurrected (there were several other documents in the past that attempted to do this or something
> close to it).

Thanks; that too looks like overkill for what I need.

> Nothing exists as an IETF standard for what you want. Whether you can use something that others are
> working on or not, I cannot say. I find these documents by googling :).

I will try to do a better job of googling.

> The options ones that presently exist are at: http://www.iana.org/assignments/dhcpv6-
> parameters/dhcpv6-parameters.xml, and I don't think anything there works for what you want.

Right, I took a look there and didn't see anything.

> You could always use Vendor Options (option 17).

OK, that would satisfy what I was meaning when I said:

  "A DHCPv6 option that returned opaque data could also be used as
   a kludge but I would rather not have to do that."

But, maybe it wouldn't be so bad, plus (correct me if I am wrong)
it has the distinct advantage that it is already implemented in
widely-deployed DHCPv6 implementations, right?

Thanks again for the help,

Fred
fred.l.templin@boeing.com

> - Bernie
> 
> -----Original Message-----
> From: Templin, Fred L [mailto:Fred.L.Templin@boeing.com]
> Sent: Monday, July 07, 2014 4:10 PM
> To: Bernie Volz (volz); Andre Kostur
> Cc: dhcwg@ietf.org
> Subject: RE: [dhcwg] Informational IPv6 prefix option for DHCPv6
> 
> Hi Bernie,
> 
> Thanks. At first glance, this looks like it is too tightly wrapped around DHCPv6 PD for what I am
> after. I want something very simple that is somehow related to PD but at the same time independent of
> PD.
> 
> So again, to my link model, I have a link on which there are one or more delegating routers and lots
> and lots of requesting routers.
> To get the information I am looking for, I could set the delegating routers to include the aggregated
> prefix in RA PIOs with the 'A' and 'L' bits set to 0. But, that means that I would need to set up some
> manual configuration on each of the delegating routers and I really don't want to have to do that.
> 
> Much better would be to have the DHCPv6 server include the aggregated prefix in a simple informative
> DHCPv6 option as a single administrative touch point. The delegating routers are then simpler and less
> prone to misconfigurations, and the requesting routers get the PD and aggregated prefix information
> they need in a single DHCPv6 request.
> 
> I think a while back there was some discussion about including PIOs in
> DHCPv6 messages. Did that hit some kind of roadblock? Because, I think I now have an interesting use
> case for it.
> 
> Thanks - Fred
> fred.l.templin@boeing.com
> 
> > -----Original Message-----
> > From: Bernie Volz (volz) [mailto:volz@cisco.com]
> > Sent: Monday, July 07, 2014 12:57 PM
> > To: Templin, Fred L; Andre Kostur
> > Cc: dhcwg@ietf.org
> > Subject: RE: [dhcwg] Informational IPv6 prefix option for DHCPv6
> >
> > There was a draft to do something like this. But I think it died. See
> > http://tools.ietf.org/html/draft-ietf-dhc-dhcpv6-prefix-pool-opt
> >
> > - Bernie
> >
> > -----Original Message-----
> > From: dhcwg [mailto:dhcwg-bounces@ietf.org] On Behalf Of Templin, Fred
> > L
> > Sent: Monday, July 07, 2014 3:44 PM
> > To: Andre Kostur
> > Cc: dhcwg@ietf.org
> > Subject: 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
> > _______________________________________________
> > dhcwg mailing list
> > dhcwg@ietf.org
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