Re: SLAAC vs DHCPv6 (Re: RFC4941bis: consequences of many addresses for the network)

[Brian E Carpenter <[e-mail]>]

On 28-Jan-20 10:44, Fernando Gont wrote:
> On 26/1/20 17:47, Brian E Carpenter wrote:
>> On 27-Jan-20 09:22, Simon Hobson wrote:
>>> Gyan Mishra <[e-mail]> wrote:
>>>
>>>> The beauty behind SLAAC is that it works “out of the box” PNP like features makes it very user friendly to initiatally deploy.
>>>
>>> Remember that DHCP for IPv4 generally works "out of the box" for most users. Certainly in the SOHO market, the presence of a built in, auto-configured, and enabled DHCP server in the route means that the user just "plugs it in and it works". By the time you get to a level of network complexity where that isn't the case, then there is normally a network admin either on the staff or hired n as needed.
>>>
>>> If that isn't working reliably for users in the IPv6 world then that suggests the various components needed haven't reached the same level of completeness & correctness "mostly" available in the IPv4 world. It isn't an argument that DHCPv6 "doesn't work".
>>
>> It's actually a historical accident. At the time that SLAAC was designed, DHCP(v4) wasn't mature and the state of the art in autoconfiguration was Appletalk, Novell IPX, and DECnet Phase IV. It really doesn't matter now. We can't roll the clock back.
> 
> Well, we *could* end the pointless religious battle, mandate both SLAAC 
> and DHCPv6, and let admins and operators run their networks in whatever 
> way they please.

That still doesn't resolve the issue of the lack of feature equivalence between RAs and DHCPv6, and there would some interesting discussions around which options need to be MTI. For example, is PD mandatory to implement? It would be interesting to see a draft (v6ops, perhaps?). However, I imagine that the constrained node people would have something to say if we changed this to a MUST:

"...all hosts SHOULD implement address configuration via DHCPv6." [RFC8504, section 6.5]

   Brian
> 
> Given the current state of affairs, in lots of places folks resort to 
> doing *both* SLAAC + DHCPv6 (for various reasons), leadind to 
> non-deterministic results, higher maintenance costs, more pain, etc.
> 
>