Subject: Re: [dns-privacy] Call For Adoption: draft-wing-dprive-dnsodtls

From: "Jørgen Hovland" <[email-masked]>
Date: 26 May 2015 19:27:48 +0000 (UTC)

At 03:04 26/05/2015 (UTC), Paul Hoffman wrote:

> Is the latency for an established TLS connection any worse than for a
DTLS connection? It would be good to see numbers if this is the case.

I did a test. The difference seems to be so small that it doesn't matter.

However,
DTLS handshake seems to be a bit slower than TLS handshake (not including TCP connect or DTLS cookie code).
Additionally, if I use the openssl CLI as DTLS server instead of my code, the DTLS handshake increases to around 34ms.
TCP connect takes around 9.1ms between my test-servers.

If you assume that the openssl CLI correctly implements a normal DTLS handshake while my code doesn't (due to no cookie code), TLS is faster than DTLS by around 2ms (8.4%) when a full connect/handshake with one write+read is done.

Server/client 500km apart from each other with simple echo server/round trip test:

TCP data read: 18, time spent write+read: 9.16038ms. Time spent TLS handshake 23.3289ms.
TCP data read: 18, time spent write+read: 9.07797ms. Time spent TLS handshake 21.4217ms.
TCP data read: 18, time spent write+read: 9.10591ms. Time spent TLS handshake 21.1549ms.

TCP data read: 18, time spent write+read: 9.05283ms. Time spent TLS handshake 21.1289ms.
TCP data read: 18, time spent write+read: 9.02824ms. Time spent TLS handshake 21.2273ms.
TCP data read: 18, time spent write+read: 9.06903ms. Time spent TLS handshake 21.1971ms.
TCP data read: 18, time spent write+read: 9.07378ms. Time spent TLS handshake 21.3058ms.

UDP data read: 18, time spent write+read: 9.02713ms. Time spent DTLS handshake: 23.1482 ms.
UDP data read: 18, time spent write+read: 9.06344ms. Time spent DTLS handshake: 22.3601 ms.
UDP data read: 18, time spent write+read: 8.97628ms. Time spent DTLS handshake: 23.1001 ms.
UDP data read: 18, time spent write+read: 9.14725ms. Time spent DTLS handshake: 22.7562 ms.
UDP data read: 18, time spent write+read: 9.0721ms. Time spent DTLS handshake: 22.0508 ms.
UDP data read: 18, time spent write+read: 9.34728ms. Time spent DTLS handshake: 21.7002 ms.

(disclaimer: I assume my numbers are correct)

At 03:04 26/05/2015 (UTC), Paul Hoffman wrote:

On May 25, 2015, at 6:54 PM, Guangqing Deng <[email-masked]> wrote:

> Resolution latency is very crucial for DNS system and the latency of DNS-over-DTLS is relatively low compared with DNS-over-TLS.

Is the latency for an established TLS connection any worse than for a DTLS connection? It would be good to see numbers if this is the case.

--Paul Hoffman

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From: Phillip Hallam-Baker <[email-masked]>
Date: Wed, 27 May 2015 14:06:01 -0400

Any chance you could add in a straight UDP round trip measurement so we
have a benchmark to compare like with like?

On Tue, May 26, 2015 at 3:27 PM, Jørgen Hovland <[email-masked]> wrote:

> Additionally, if I use the openssl CLI as DTLS server instead of my code,
> the DTLS handshake increases to around 34ms.
> If you assume that the openssl CLI correctly implements a normal DTLS
> handshake while my code doesn't (due to no cookie code), TLS is faster than
> DTLS by around 2ms (8.4%) when a full connect/handshake with one write+read
> is done.
>
>
> > Resolution latency is very crucial for DNS system and the latency of
> DNS-over-DTLS is relatively low compared with DNS-over-TLS.
>
> Is the latency for an established TLS connection any worse than for a DTLS
> connection? It would be good to see numbers if this is the case.
>
> --Paul Hoffman