Re: [dhcwg] ***CAUTION_Invalid_Signature*** Re: Alignment between softwire-map-dhcp and dhc-dhcpv4-over-dhcpv6 drafts

"Wojciech Dec (wdec)" <> Mon, 11 November 2013 14:29 UTC

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From: "Wojciech Dec (wdec)" <>
To: Qi Sun <>
Thread-Topic: [dhcwg] ***CAUTION_Invalid_Signature*** Re: Alignment between softwire-map-dhcp and dhc-dhcpv4-over-dhcpv6 drafts
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Date: Mon, 11 Nov 2013 14:28:56 +0000
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Subject: Re: [dhcwg] ***CAUTION_Invalid_Signature*** Re: Alignment between softwire-map-dhcp and dhc-dhcpv4-over-dhcpv6 drafts
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The descriptive text that was proposed is not essential to the spec (about a stateless DHCPv6 option), nor to comprehend it, (nor to comprehend MAP for that matter). The essence really is that, "if you one need DHCPv4 leases, use DHCPv4". This point has nothing to do with how MAP does or does not use stateful dhcp, etc.

Re your questions, most of the answers point the way back to MAP 1:1 mode, where whichever way it is done, the IPv4 address does NOT need to be coupled to the IPv6 address.

Thanks for bringing out the issue in draft-08, which ought to be fixed before publishing: The MAP architecture requires an IPv6 prefix for the CE. It does NOT dictate how that prefix is provisioned, and whether it is stateful or not. An RA or DHCP-PD prefix, or static config are all fine here (though some may prefer dhcp say).


From: Qi Sun <<>>
Date: Monday, 11 November 2013 07:12
To: Wojciech Dec <<>>
Cc: Cong Liu <<>>, "<>" <<>>, "<>" <<>>, "<>" <<>>, "<>" <<>>, "<>" <<>>, "<>" <<>>, "<>" <<>>
Subject: Re: [dhcwg] ***CAUTION_Invalid_Signature*** Re: Alignment between softwire-map-dhcp and dhc-dhcpv4-over-dhcpv6 drafts

Hi Woj,

2013/11/11 Wojciech Dec (wdec) <<>>
>The solution described in this document is suitable for provisioning IPv4
>addressing and other configuration necessary for establishing softwire
>connectivity using DHCPv6. This means that the lifetime of the IPv4
>configuration is bound to the lifetime of the DHCPv6 lease. For MAP-E and
>MAP-T, this is necessary due to the mapping between the IPv4 and the IPv6
>address. Lightweight 4over6 allows for the de-coupling of the IPv4 and
>IPv6 lease times. If this is required, then DHCPv4 over DHCPv6
>[ietf-dhc-dhcpv4-over-dhcpv6] should be used for IPv4 address leasing.

It's close, but not quite as MAP doesn't mandate stageful DHCP of any kind
(SLAAC can also be used).

I think this paragraph should be added.
For your concern, I think the text can be modified to:
  "This means that the lifetime of the IPv4 configuration is bound to the lifetime of the IPv6 configuration."

Well, not quite: The lifetime of the IPv4 configuration in MAP *can*, but doesn't have to be bound the IPv6 configuration.

[Qi] Could you please elaborate? This is what I found in draft-ietf-softwire-map-08:

   The MAP provisioning parameters, and hence the IPv4 service itself,
   is tied to the End-user IPv6 prefix lease; thus, the MAP service is
   also tied to this in terms of authorization, accounting, etc.  The
   MAP IPv4 address, prefix or shared IPv4 address and port set has the
   same lifetime as its associated End-user IPv6 prefix.

The essence is that if someone want to use DHCPv4 (for DHCPv4 options, or DHCPv4 leases) then they should use DHCPv4 over DHCPv6.

[Qi] As I see, the text proposed reflects this essence (dynamic IPv4 address leasing  and DHCPv4 options).

Best Regards,