Re: Question about NetBSD implementation of IPv6 SLAAC and RFC4941

[Roy Marples <roy%marples.name@localhost>]

On 05/04/2020 23:23, Christos Zoulas wrote:
> > Maybe your definition of static differs from mine.
> > By static I mean you have addresses and routes setup in say /etc/ifconfig.re0
> > Can you clarify?
>
> I can have a static address but the routing information can be dynamic. For example if I am connected to a network that has access to more than one ISP.

Ah, now we are getting interesting! So, some questions:

1) Are you soliciting a router or just waiting for an RA to magically appear?
   This is fairly important as recent RFC 7772 vastly reduces broadcasts to the
   network - it unicasts a lot more than it broadcasts - and makes each node
   wanting a router actually solicit one.
   If you're not using dhcpcd to solicit, what are you using?

2) What's the expectation with many routers and the current becomes unreachable?
   dhcpcd will spot this thanks to RTM_MISS but the kernel won't. Instead it
   will wait for the next RA to arrive and then evalute matters, which again
   brings me back to RFC 7772 and the timeliness of RA's arriving.
   Now this is fixable in the kernel for sure, but I for one like to solve
   problems in one place and in this case already have.

3) How dynamic do you want your routing?
   I enjoy using wireless on my pinebook - but it's slow and when I compile
   over NFS I stick ethernet in via a USB dongle.
   dhcpcd will automatically prefer wired over wireless and change the
   routing (this assumes that wired and wireless share the same prefix).
   The changeover is pretty seamless, the kernel cannot do this and I doubt
   anyone will make that happen.

I would talk about dynamic addressing as well - or rather IP address sharing 
which is pretty unique to NetBSD at the IPv6 level, but as your addresses are 
static we can park that for another day.

Roy