ICMPv6 "too-big" packets ignored (filtered ?) by Cloudflare farms

Sun Mar 10 03:12:08 UTC 2019

Mark Andrews wrote:

 > Why should the rest of the world have to put up with their inability
 > to purchase devices that work with RFC compliant data streams.

Because RFCs specifying IPv6 are broken.

That is, as PTB is generated against multicast, we should block
them. Then, not blocking PTB against unicast needs very deep
inspection, which is not possible with some network processors.

See

     https://meetings.apnic.net/32/pdf/pathMTU.pdf

for details.

William Herrin wrote:

 > IPv4's inventors did a brilliant job with what they knew at the
 > time. IPv6's inventors not so much. Sadly, they were too busy
 > figuring out how to make IPv6 integrate well with ATM. Seriously, >  
if you dig up a copy of the original IPng book I think it's chapter 3.

Indeed.

IPv6 replaced link broadcast by various kind of multicast addresses
only to increase MLDP overhead, because IPng WG believed that
simple broadcast does not but more complicated multicast does
work with IP over ATM.

                             Masataka Ohta