[metaxy2]

> In my experience, it is rare for a network to correctly generate Time Exceeded messages for both IPv4 and IPv6.

Doesn't that make it more one of those situations where the non-documented behavior has become the de facto standard, rather than "wrong" exactly? (I guess it depends on whether that decision is being made consciously by the implementors or just for lack of knowledge of the standards.)

[toast0]

People who filter out all ICMP are probably unaware of the standard, but router implementors that limit ICMP rates are balancing transparent observability with the need to keep the equipment running.

I guess you could provision the router cpus so they could send ICMPs for line rate incoming packets that must be dropped, but that doesn't seem like a good cost tradeoff.