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Re: [TLS] DTLS 1.3 ACKs

Ilari Liusvaara <ilariliusvaara@welho.com> Sat, 01 July 2017 17:01 UTC

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Date: Sat, 01 Jul 2017 20:01:03 +0300
From: Ilari Liusvaara <ilariliusvaara@welho.com>
To: Eric Rescorla <ekr@rtfm.com>
Cc: "tls@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] DTLS 1.3 ACKs
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On Sat, Jun 24, 2017 at 12:05:44PM -0700, Eric Rescorla wrote:
> On Sat, Jun 24, 2017 at 9:47 AM, Ilari Liusvaara <ilariliusvaara@welho.com>
> wrote:
> 
> It seems ACKs work in terms of RSNs. This generates a weirdness that
> > a fragment can be known with multiple IDs, in case a packet gets
> > delayed enough to trigger retransmission but the original is then
> > accepted. But OTOH, retransmission at fragment granularity is useful
> > with potentially "obese" messages like Certificate.
> >
> 
> This is the calculation I made as well. Note that removing aliasing in this
> fashion actually is useful in measuring packet loss (this is what QUIC
> does).

IMO, since handshake only occurs once per connection and DTLS needs to
be implemented on all kinds of constrained devices (on both client and
server sides), simplicity is more important than performance. Also,
packet loss estimates do not seem useful: There are far too few packets
to get useful statistics.





-Ilari

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