3 ms·

PMTU-D will save their ass in some cases. But it's not safe to assume all routers in the path will respond to ICMP.

• toast0 7y ago
  It doesn't matter that the routers respond to ICMP, it matters that they generate them, and that they're addressed properly, and that intermediate routers don't drop them. Some routers will generate the ICMPs, but are rate limited, and the underlying poor configuration means that the rate limits are hit continously and most connections are effectively in a path mtu blackhole.
  • vlan0 7y ago
    >It doesn't matter that the routers respond to ICMP, it matters that they generate them, and that they're addressed properly, and that intermediate routers don't drop them. >Some routers will generate the ICMPs, but are rate limited, and the underlying poor configuration means that the rate limits are hit continously and most connections are effectively in a path mtu blackhole. Sure. But I'm not about to sit here and name all the different reasons for folks. And since most here do not have a strong networking background running consumer grade routers at home, it seemed most applicable. I could have used a more encompassing term like PMTU-D blackhole, but I didn't.