Re: [ipv6] Node Requirements: Elevating DHCPv6 from MAY to SHOULD

Markus Hanauska <hanauska@equinux.de> Tue, 31 May 2011 13:50 UTC

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Subject: Re: [ipv6] Node Requirements: Elevating DHCPv6 from MAY to SHOULD
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From: Markus Hanauska <hanauska@equinux.de>
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Date: Tue, 31 May 2011 15:50:16 +0200
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To: Mark Smith <ipng@69706e6720323030352d30312d31340a.nosense.org>
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On 2011-05-31, at 15:28 , Mark Smith wrote:

>> 1. Manual configured IP
>> 2. DHCP
>> 3. SLAAC with Privacy Extension
>> 4. SLAAC with Interface ID
>> 
> 
> Some people might prefer SLAAC over DHCP.

That's why things like these are usually configurable. Just because there exists a well defined default order doesn't mean you are not allowed to manually override it, does it?

> For example, if I were
> attached to a public hot spot with my laptop, then I'd want to use 
> SLAAC with Privacy Extensions in preference to DHCP, even if there is a
> DHCP server available.

I doubt this would buy you anything. See, if the network admin was okay with people using SLAAC, he wouldn't hand out IP addresses through DHCPv6. Either he would not operate a DHCPv6 server at all or he would only operate a stateless DHCPv6 server to hand out DNS, NTP and other useful server addresses. Do you know of any device that supports DHCPv6 but not SLAAC? I don't. Would such a device be even standard conform? So if the admin operates a DHCPv6 server at that hotspot handing out IP address, he probably wants you to use those addresses and all other addresses may, for example, not be routable, that means if you override the order above, your outgoing traffic works within the hotspot only, but you cannot reach the rest of the Internet any longer and since hotspots usually put the user into virtual LANs and don't allow direct traffic between two hotspot users, there is nothing you could do while being connected to the hotspot.

Regards,
Markus