Re: Re: Just how big is IPv6?
  By: Arelor to Deon George on Thu Jan 02 2025 06:34 am

Howdy,

 > Take SLAAC as an example. It only works on a narrow set of scenarios and
 > can't convey all the information traditional DHCP does. On a regular IPv4
 > network where you want hosts to acquire a gateway, ntp server and dns server
 > upon boot, you use DHCP to provide them all with it. SLAAC only gets the
 > basics right (IP, gateway and dns) but if you are serious you are back to
 > DHCP. For even more fun, SLAAC only works within its narrow scenario IF it
 > operates on a network segment of EXACTLY a harcoded size.

Other than ntp, what else do you need from DHCP? Most (modern?) OS's these days
have NTP setup by default - so supplying clients with NTP details is often no
longer required.

If you wanted to limit the outgoing connections to an NTP server, to use your
NTP server, (and/or DNS server), then you can use NAT rules on your gateway for
that. (That's what I do anyway.)

I thought SLAAC worked pretty well - I work for a large company (many 1000's
employees), and the IT team turned on IP6 and nobody noticed - in fact I dont
recall any announcement about it. I only noticed when I started seeing
connections (from work) to my home server over IP6.

 > Then there is the fact my current home deployment is pretty much
 > non-replicable on IPv6 at all unless the ISP wants to cooperate. Hint: ISP
 > usually don't. Long story short, I have multiple local address spaces (think

 > If you want to break an IPv6 LAN into segments such as the above you are
 > supposed to pick the prefix provided to you by your ISP and then use DHCP-PD
 > (aka prefix delegation) to break your network into smaller prefixes and
 > assign each to each segment. This would be good and fancy if it worked, but

Hmm... its worked for me, but then my setup my not be as complicated as yours? I
get an /60 from my current ISP (my previous one gave me a /56) - and my router
dished it out as /64's to each lan interface as it needed to. At one point, I
dished out a /62 to a downstream router, and it split it up to /64s for it's lan
interfaces.

I've since turned all that off, as when I changed ISPs, my prefix changed and I
wanted to flatten my network a bit anyway.

I know not all ISPs here are providing IP6 to clients, but that's normally one
of the things I look for when changing. Even my mobile phone uses IP6 over IP4
from my mobile provider.


...oEoN
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