Re: [radext] [dhcwg] [homenet] PPP, DHCPv6 and Prefix Delegation

"Bernie Volz (volz)" <> Tue, 19 November 2013 13:20 UTC

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From: "Bernie Volz (volz)" <>
To: Athanasios Douitsis <>
Thread-Topic: [dhcwg] [homenet] PPP, DHCPv6 and Prefix Delegation
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Date: Tue, 19 Nov 2013 13:19:59 +0000
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Cc: "" <>, "" <>, "Roberta Maglione (robmgl)" <>, " WG" <>, Michael Richardson <>
Subject: Re: [radext] [dhcwg] [homenet] PPP, DHCPv6 and Prefix Delegation
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I guess from RFC 4818, Delegated-IPv6-Prefix is used for PD. Whereas it says:

   The Framed-IPv6-Prefix attribute [4] is not designed to support
   delegation of IPv6 prefixes to be used in the user's network, and
   therefore Framed-IPv6-Prefix and Delegated-IPv6-Prefix attributes may
   be included in the same RADIUS packet.

But, I'm not really clear if that ends up mapping to OPTION_PD_EXCLUDE for the Framed-IPv6-Prefix. Perhaps if the case is as in your example (Framed-IPv6-Prefix is contained by Delegated-IPv6-Prefix, but not equal) then using the Framed-IPv6-Prefix for OPTION_PD_EXCLUDE makes some sense?

-          Bernie

From: dhcwg [] On Behalf Of Athanasios Douitsis
Sent: Tuesday, November 19, 2013 7:40 AM
To: Bernie Volz (volz)
Cc:; Michael Richardson; Roberta Maglione (robmgl); WG;
Subject: Re: [dhcwg] [homenet] PPP, DHCPv6 and Prefix Delegation

Hello (thanks for the answer),
The uplink connection between the delegating and the requesting router will be in many cases enumerated with a prefix dictated by the Framed-IPv6-Prefix value. If this uplink prefix is going to be a part of the greater prefix that will be delegated, we would in effect have to include the value of the Framed-IPv6-Prefix in the OPTION_PD_EXCLUDE.
Example, if a delegating router makes a RADIUS request and gets the following attributes in the reply:

Then the delegating router should
1)send an RA in the client uplink interface with 2001:dead:beef::/64. The uplink is enumerated with that /64.
2)Afterwards, when requested for PD, it should reply with the 2001:dead:beef::/56 to the requesting router, but excluding the 2001:dead:beef::/64 from that /56 by putting it in the OPTION_PD_EXCLUDE.
So in effect, the Framed-IPv6-Prefix has been copied in the OPTION_PD_EXCLUDE option.
If I have misunderstood something in the RFC or the discussion, I'd be grateful if you would correct me.
Thanks very much,

On Tue, Nov 19, 2013 at 2:07 PM, Bernie Volz (volz) <<>> wrote:
Why would it ever be copied into that option? That makes no sense to me.

- Bernie (from iPad)

On Nov 19, 2013, at 6:16 AM, "Athanasios Douitsis" <<>> wrote:

(i.e. have a configuration option to use the Framed-IPv6-Prefix value in the prefix exclude option instead of an RA)

Correction, the above is incorrect, as has been rightly pointed.
Are there any cases where the Framed-IPv6-Prefix value will not be copied as-is in the OPTION_PD_EXCLUDE value?

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Athanasios Douitsis