ICMPv6 "too-big" packets ignored (filtered ?) by Cloudflare farms
Saku Ytti
saku at ytti.fi
Mon Mar 4 19:06:30 UTC 2019
Hey Jean,
> I confess using IPv6 behind a 6in4 tunnel because the "Business-Class" service
> of the concerned operator doesn't handle IPv6 yet.
>
> as such, I realised that, as far as I can figure, ICMPv6 packet "too-big" (rfc 4443)
> seem to be ignored or filtered at ~60% of ClouFlare's http farms
Might be related to this:
https://blog.cloudflare.com/path-mtu-discovery-in-practice/
If you run ECMP then the hash algorithms make no guarantees ICMP
messages generated by transit devices reach the correct host.
--
++ytti
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