IPv6 "bloat" history

Tue Mar 29 09:21:14 UTC 2022

Hello Ohta-san

> An ARP table entry can be created when an IP address is assigned during
> registration process and destroyed if the registration is invalidated.
> 
> Or, do I misunderstand anything?

You're perfectly correct. This is exactly what the registration would be for. I'm concerned about its adoption that I do not see coming on Wi-Fi/ Ethernet, even for v6 (SLAAC) where the problem is a lot worse*.

The IoT world already adopted the registration model, though. Millions of nodes on 802.15.4 radios are deployed to prove it works. We even redistribute RFC 8505 in routing protocols that carry host routes in IoT networks (RPL), which is how we avoid your lookup issue on a wide low power mesh network.

Extending the registration to IPv4 is easy, we could even use mapped addresses and be done. But what magic will trigger attention / adoption when adoption is not showing in IPv6?

Keep safe;

Pascal

* APs today snoop DHCP; DHCP is observable and stateful, with a lifetime that allows to clean up. So snooping it is mostly good enough there. The hassle is the SL in SLAAC which causes broadcasts and is not deterministically observable; this problem is specific to IPv6. We already have the registration to avoid snooping DHCP and SLAAC; yet we do not observe any adoption in mainline APs and STAs. 

> -----Original Message-----
> From: Masataka Ohta <mohta at necom830.hpcl.titech.ac.jp>
> Sent: mardi 29 mars 2022 10:57
> To: Pascal Thubert (pthubert) <pthubert at cisco.com>; nanog at nanog.org
> Subject: Re: IPv6 "bloat" history
> 
> Pascal Thubert (pthubert) wrote:
> 
> > I tried exactly what you suggested for IPv6 with RFC 8505 and 8929.
> > But to few people in mainstream networks realize what you just said.
> 
> I found, theoretically by reading 802.11 specification, broadcast/multicast
> reliability problem and reported to
> IPv6 WG about 20 years ago. So, I'm pleased to know that some people
> recognize it as a real problem and worked on it. Thank you.
> 
> > It started long long ago with the idea to use inverse ARP for the
> > registration, I guess it is still doable but I am not optimistic about
> > adoption considering that v6 is a lot worse with more addresses and
> > DAD.
> 
> Aren't IP addresses are assigned from APs? Then, the APs can construct ARP
> table without actually running ARP or inverse ARP, I'm afraid.
> 
> > We are editing the piece on proxy ARP at this very moment at .11me.
> > APs are indeed supposed to proxy both v4 and v6. What is less clear is
> > how they form a deterministic state for that.
> 
> An ARP table entry can be created when an IP address is assigned during
> registration process and destroyed if the registration is invalidated.
> 
> Or, do I misunderstand anything?
> 
> 						Masataka Ohta