IPv6 "bloat" history

Pascal Thubert (pthubert) pthubert at cisco.com
Thu Mar 31 12:18:19 UTC 2022

Don't sigh! You envisioned it and we built it, William.

We have IPv6 mesh networks with thousands on nodes per mesh deployed around you. The standard is called WI-SUN. WI-SUN totals millions of nodes deployed in North America; so what you described cannot not only be envisioned as you did, it can be built and deployed at scale, even on low power far reach wireless.

The core L3 components for Wi-SUN are RFC 8505 which is your link state ND thingy, RFC 6550 that does the routing over what OSPF called P2MP and which really means non-transitive, and RFC 9010 that redistribute the former in the latter. We are now working on registering multicast, anycast and prefixes in the same model.

It's just that the wired world (including operators) are mostly unaware of these capabilities. Whether they are even interested is not a given either. Louis the XVth said "après moi le déluge". I read pretty much the same thing on the list in the recent days as a migration strategy. 

Certainly, complaining from a comfort zone is a lot easier than acting out to solve the problem. "La critique est aisée mais l'art est difficile" is another good one.

I claim that bashing at the IETF for IPv6 as it was 20 years ago is unfair and that a little refresh / resync is in order. If what we produced since in an attempt to solve the issues you describe can help, then ask for it, amend it, say something, so something.

Today, decoupling the L1/2 (physical) network from the L3 abstractions of subnet and link is totally doable. This yields a world of possibilities for deployments. For all those (or the very few) who care, there's https://datatracker.ietf.org/doc/html/draft-thubert-6man-ipv6-over-wireless-06

Keep safe;


PS : When I say that DHCP mostly does the trick is not that I like it, but that customers (think EVPN) are reasonably happy with the result, while SLAAC is a lot worse for pretty much the whole collection of its design points, and cherry on the cake, the onlink model.

> -----Original Message-----
> From: William Allen Simpson <william.allen.simpson at gmail.com>
> Sent: jeudi 31 mars 2022 13:44
> To: nanog at nanog.org
> Cc: Pascal Thubert (pthubert) <pthubert at cisco.com>; Masataka Ohta
> <mohta at necom830.hpcl.titech.ac.jp>
> Subject: Re: IPv6 "bloat" history
> On 3/29/22 5:21 AM, Pascal Thubert (pthubert) via NANOG wrote:
> > * 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.
> >
> [heavy sigh]
> All of these things were well understood circa 1992-93.
> That's why the original Neighbor Discovery was entirely link state.
> ND link state announcements handled the hidden terminal problem.
> (That is, where node A can hear node B, node B can hear node C, and node C
> can hear node A, but A cannot hear C.)  ND LSAs are/were flexible enough to
> handle both AP (cell) and mesh (AMPR) networks.
> Thus, it was not reliant on central Access Points.  We envisioned mesh
> networks were the future.  Each node should handle its own discovery and
> routing.
> SLAAC is bloat.
> RIPv6 is bloat.
> DHCPv6 is bloat.
> Those are reasons operators have been complaining about IPv6.

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