IPv6 "bloat" history

Masataka Ohta mohta at necom830.hpcl.titech.ac.jp
Thu Mar 31 15:10:58 UTC 2022

Pascal Thubert (pthubert) wrote:

> 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*.

You can't expect people still working primarily on v6 have
much sense of engineering.

> * 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.

As broadcast/multicast packets are first sent to APs as unicast
packets with ACKs, snooping by APs should be reliable at L2.

So, by snooping DAD, which is ugly, ARP table can be constructed.

A problem, however, is that there is no ACK above L2, that is,
there is no end to end ACK, which means, if something goes wrong
above L2, the result can be weird.

						Masataka Ohta

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