Re: Broken PMTUD / ICMP blackhole?
tomas writes:
> I don't know the error message by heart, but here, it seems
> the message size is too big for your local MTU...
Celejar writes:
> Yes, I think this is pretty clear. The local wifi interface has the
> standard MTU of 1500, so it rejects packets larger than that.
> With nnnn = 1472, I get, at least sometimes:
> From 192.168.43.245 icmp_seq=2 Frag needed and DF set (mtu = 1472)
tomas writes:
> This is definitely an ICMP message you receive from some upstream
Celejar writes:
> Yes, except that I don't see this message consistently. I assume that's
> some sort of upstream flakiness.
It has to do with TLS. Recent changes in the protocol have had the
result that it sometimes sends packets too large for the standard MTUs.
These packets cannot be fragmented, so you get intermittent problems
that seem like they must be at the other end. I've had to reduce my MTU
to 1300.
--
John Hasler
jhasler@newsguy.com
Elmwood, WI USA
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