Slow connections (something other than packet fragmentation?)

Peter Brant peter.brant at
Tue Apr 28 09:52:52 PDT 2015

On Tue, Apr 28, 2015 at 12:27 AM, David Woodhouse <dwmw2 at> wrote:
> On Tue, 2015-04-28 at 00:14 +0200, Peter Brant wrote:
>> >
>> Ah, I didn't know that the performance overhead of using TCP was that severe.
> Usually it shouldn't be. But if you have a lossy path, it's going to
> hurt a lot. It's best to eliminate it first.
Just a short follow-up to report that in my particular case, the
performance overhead of using TCP was indeed that severe.

The upstream firewall at my workplace is now passing DTLS traffic and
I'm happy to report that I was able scp a large (170MB) tgz file down
from an internal server with an average transfer rate (over four
transfers) of 3.7 MB/s as compared with about 100 KB/s yesterday. As
another point of comparison, the network admins were able to revive
the previous IPsec VPN too. Average transfer speed there with the same
test was 2.4 MB/s.

In short, I'm converted. Thanks again for the help.


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