Re: [dhcwg] WGLC for draft-ietf-dhc-dhcpv4-over-dhcpv6-03 - Respond by Dec 9, 2013

<ian.farrer@telekom.de> Wed, 27 November 2013 14:31 UTC

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From: <ian.farrer@telekom.de>
To: <volz@cisco.com>, <sunqi.csnet.thu@gmail.com>
Date: Wed, 27 Nov 2013 15:31:34 +0100
Thread-Topic: [dhcwg] WGLC for draft-ietf-dhc-dhcpv4-over-dhcpv6-03 - Respond by Dec 9, 2013
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Subject: Re: [dhcwg] WGLC for draft-ietf-dhc-dhcpv4-over-dhcpv6-03 - Respond by Dec 9, 2013
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Hi Bernie,

I wasn’t necessarily advocating that other options should be carried in the BOOTREQUEST/REPLYV6 messages, just that the current wording in the draft could be understood to mean that all DHCPv6 options are allowable with the exceptions of OPTION_DHCP4_O_DHCP6_ENABLE and OPTION_DHCP4_O_DHCP6_SERVER (the only ones expressly forbidden).

However, I can see that there is a case whereby other options may need to be transported within the DHCPv4 over DHCPv6 messages: If you are using dynamic, shared IPv4 address leases for softwire clients, then you need a way of learning the IPv6 address that the client will use for it’s 4over6 tunnel endpoint otherwise you can’t provision the tunnel concentrator with all of the necessary parameters.

This IPv6 address needs to be sent from the client to the DHCPv4o6 server as it’s validity is bound to the lease lifetime of the IPv4 address + ports. It would then make sense to allow this information to also be carried within BOOTREQUESTV6 messages as DHCPv6 options alongside the OPTION_BOOTP_MSG they are related to.

So, I agree that there should be some wording to allow the inclusion of options related to configuring IPv4 in a v6 only network, without allowing any/every DHCPv6 option out there.

Ian



From: "Bernie Volz (volz)" <volz@cisco.com<mailto:volz@cisco.com>>
Date: Wednesday, 27 November 2013 15:01
To: Qi Sun <sunqi.csnet.thu@gmail.com<mailto:sunqi.csnet.thu@gmail.com>>, Ian Farrer <ian.farrer@telekom.de<mailto:ian.farrer@telekom.de>>
Cc: "dhcwg@ietf.org<mailto:dhcwg@ietf.org>" <dhcwg@ietf.org<mailto:dhcwg@ietf.org>>
Subject: RE: [dhcwg] WGLC for draft-ietf-dhc-dhcpv4-over-dhcpv6-03 - Respond by Dec 9, 2013

Hi:

I agree with Qi that these options should not be used for the BOOTREQUESTV6/BOOTREPLYV6 messages.

While we might want to think about some words to indicate that these messages should not typically have options (other than the OPTION_BOOTP_MSG option), I think we do want to be careful as someone might have a reason to include some options that could be useful to the 4o6 DHCP Server or Client in the future.

The bottom line is that these messages SHOULD NOT be used to configure DHCPv6 client and interface related settings – hence why the OPTION_DHCP4_O_DHCP6_ENABLE and OPTION_DHCP4_O_DHCP6 options SHOULD NOT be present. Normal DHCPv6 messages should be used for configuring anything related to DHCPv6 (including the two just mentioned options).


-          Bernie

From: Qi Sun [mailto:sunqi.csnet.thu@gmail.com]
Sent: Wednesday, November 27, 2013 6:10 AM
To: <ian.farrer@telekom.de<mailto:ian.farrer@telekom.de>>
Cc: Bernie Volz (volz); dhcwg@ietf.org<mailto:dhcwg@ietf.org>
Subject: Re: [dhcwg] WGLC for draft-ietf-dhc-dhcpv4-over-dhcpv6-03 - Respond by Dec 9, 2013


Hi Ian,

Thanks for comments.


On 2013-11-27, at 下午5:50, <ian.farrer@telekom.de<mailto:ian.farrer@telekom.de>> <ian.farrer@telekom.de<mailto:ian.farrer@telekom.de>> wrote:

Section 8, the sentence beginning ‘The client that intends…’ should read ‘A client that intends….'

[Qi] Will correct it.



Section 8  - Question regarding the sentence ‘The 4o6 DHCP client MUST NOT request the DHCPv4-over-DHCPv6 Enable Option nor the 4o6 Server Address Option in the Boot-request-v6 message’. I think that this text as written is ambiguous.

Is it meant to mean that the boot-request-v6-message can contain any DHCPv6 option with the exception of the 4o6 enable and 4o6 server options? Saying that the client may not request certainly implies that the client could include an ORO option alongside OPTION_BOOTP_MSG. Is the intention to allow this?

[Qi] The reason I added this sentence was that it's not necessary for the client to ask for the Enable Option again in Boot-request-v6 message as the DHCPv4-over-DHCPv6 function has been running. The DHCPv4-over-DHCPv6 function status should be refreshed alongside IPv6 configuration process rather than DHCPv4 over DHCPv6 process.

IMHO, the Boot-request-v6 msg and Boot-reply-v6 msg should only be used for v4-related configuration, which makes it simple.  Would it reasonable to exclude the ORO option in the two messages?

If not, why exclude requesting the 4o6 server option? Obviously, it’s pointless allowing the Enable option, but sending the 4o6 server option within the BOOTREPLYV6 to allow a dedicated DHCP4o6 server to tell the client to use unicast seems like it could be a good idea. What’s the reason for specifically excluding it?

[Qi] Allowing the client to request the 4o6 server address option would violate the Bullet 4 in section 8: the client only receives the 4o6 Server Address option but no DHCPv4 over DHCPv6 Enable option, then the client is required to ignore the 4o6 Server Address option.

IMHO, we could make it simple: the server signals the client to use unicast or multicast when the client is enabled to invoke the DHCPv4 over DHCPv6 and it's not necessary for the client to change that.

Best Regards,
Qi



There’s also a few other places in the text that need to be aligned with this (the ‘options’ description in Sec 5.2 and paragraph 8 of section 8).

Thanks,
Ian


From: "Bernie Volz (volz)" <volz@cisco.com<mailto:volz@cisco.com>>
Date: Sunday, 24 November 2013 23:02
To: "dhcwg@ietf.org<mailto:dhcwg@ietf.org>" <dhcwg@ietf.org<mailto:dhcwg@ietf.org>>
Subject: [dhcwg] WGLC for draft-ietf-dhc-dhcpv4-over-dhcpv6-03 - Respond by Dec 9, 2013

Folks, the authors of draft-ietf-dhc-dhcpv4-over-dhcpv6-03 (http://tools.ietf.org/html/draft-ietf-dhc-dhcpv4-over-dhcpv6-03.txt) believe it is ready for working group last call. Please review this draft and indicate whether or not you feel it is ready to be published. Your input is important! Please respond by Dec 9th, 2013.

At the time of this writing, there is no IPR reported against this draft.

Bernie will be the document shepherd.

Thanks,


-          Tomek & Bernie

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