RE: Adoption Call for <draft-troan-6man-universal-ra-option>

[Vasilenko Eduard <[e-mail]>]

> we defined IPv6 in such a way that it doesn't depend on having an active ISP or any kind of centralized top-down configuration.
The local DHCP server on the CPE could start leasing ULA addresses "out of the box". No dependency on others.
If an earthquake would split the apartment into 2 pieces - it would not work anyway.

DHCP has no magic. Just 2 competitive solutions (one is complex/distributed) creates a lot of excessive problems.

-----Original Message-----
From: ipv6 [mailto:[e-mail]] On Behalf Of Brian E Carpenter
Sent: Thursday, September 23, 2021 1:46 AM
To: Philip Homburg <[e-mail]>; [e-mail]
Subject: Re: Adoption Call for <draft-troan-6man-universal-ra-option>

On 23-Sep-21 01:49, Philip Homburg wrote:
>> It does exactly what it wa
>> s designed
>> to do, what we called "the dentist's office scenario" in the early 
>> days of IPn g design, actually modelled mainly on Appletalk. You can 
>> hook a few IPv6 boxes together on a wire and they will start talking 
>> to each other using SLAAC and link-local addresses. Add a router with 
>> a prefix and they will start talking t o the world using SLAAC and 
>> RA. DHCPv6 is completely unnecessary until the net work reaches a certain level of complexity.
> 
> I'm confused about the relevance of the "the dentist's office scenario".
> 
> As far as I know, the "the dentist's office scenario" is when there is 
> no router of any kind on a subnet.

Yes, I think that was the world view in ~1994 when this conversation started.
I was thinking of SLAAC, not SLAAC+RA. SLAAC starts with link-local addresses.
Certainly, a modern version of "dentist's office" is more like a homenet with several in-house routers. RA is what you get out of the box when you install an IPv6 router. Then you need ULAs unless you have an active ISP.

Just to be clear, we defined IPv6 in such a way that it doesn't depend on having an active ISP or any kind of centralised top-down configuration.
That's something we need to keep; we aren't here to support any particular business model such as an ISP-based Internet. (The very concept of "CPE" assumes that business model.)

Of course, we also need the ability to add either top-down configuration via something like DHCP, or automatic self-configuration. The latter could make DHCP redundant. There's nothing magic about DHCP; it's just an overlay on the basic IPv6 mechanisms if you want centralised top-down configuration.
If you don't want that, you don't want DHCP.

> Both RA and DHCP are equally irrelevant.
> That scenario seems completely unrelated to this discussion. Basically 
> the support we have for the "the dentist's office scenario" is that 
> hosts automatically configure a link-local address. Nothing more nothing less.
> 
> These days, most devices communiate over wifi. And it is hard to find 
> a wifi access point in a dentist's office that doesn't have a built-in router.
> 
> As the current IPv4 network shows, even the smallest networks work 
> fine with DHCP. DHCP in modern CPEs is completely automatic. So the 
> notion that a small network would need something like RA is rather weird.

I remind you that we did the basic IPv6 design, including RA, before DHCP was a thing. (Strictly speaking, it was an emerging technology.)
DHCPv6 is an add-on.

> Where RA goes beyond DHCP is in supporting multiple default routers. 
> Which is no longer a small, simple network. And in my experience, 
> having multiple routers announcing their own prefixes, creates interesting corner cases.

It does. Hence RFC8028 and PVDs.

   Brian

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