Re: [dhcwg] WGLC for draft-ietf-dhc-addr-notification - Respond by September 13, 2023

[Ole Troan <[e-mail]>]

Mark,

> On Mon, 25 Sept 2023, 23:55 Ole Troan, <otroan=[e-mail]> wrote:
> > We have had some operators' interests in this solution over scrapping switches and routers.   I think it would be helpful to hear from network operators or DHCPv6 server solutions about how viable and deployable this solution is. 
> 
> I hope we are not suggesting scrapping all switches and routers.
> Wouldn’t be much of a network then! :-D
> 
> It would be useful to hear from enterprise network operators indeed.
> We need to make it clear to them that this mechanism depends on hosts (voluntarily) notifying the DHCP server about it’s addresses. And unless that’s also enforced through the network in other ways, the information given is “just another datapoint with some probability of being correct”).
> 
> “Scraping” of routers and switches isn’t the direct alternative to DHCP address notification. Although some level of first hop security functions is likely required. I would think DHCPv6 address assignment is the obvious solution instead of this.
> 
> DHCPv6 isn't a solution when you think about what the security requirements are.

It’s a significant building block.

> The Stateful DHCPv6 Myth. No, it doesn't record IPv6 addresses in use. Neither does DHCPv4.
> https://ipv6tao.blogspot.com/2021/09/the-stateful-dhcpv6-myth-no-it-doesnt.html?m=1

That was a dreadfully opinionated blogpost…

DHCPv6 would give the network enough information to enforce which addresses a host is permitted to use. Using mechanisms like FHS (first-hop security) / SAVI.

With SLAAC there isn’t an equally robust mechanism available. And I’m not sure this helps.
As an DHCPv6 address assignment alternative the ARO option might have been better.

To emphasise, this is for the use case of a network operator requires control of addresses in use by which device. Allowing IPv6 to support that use case does not mean there are many other use cases where SLAAC is perfectly fine.

O.