Re: 1-week WGLC on recent changes in draft-ietf-mmusic-dtls-sdp

On Thu, Apr 27, 2017 at 8:44 PM, Martin Thomson <[email protected]>
wrote:

> On 28 April 2017 at 05:52, Roman Shpount <[email protected]> wrote:
> > If ClientHello is not cached, connection setup will be delayed by 5 sec
> > (DTLS re-transmit timer). This is quite noticeable and produces negative
> > client experience. So, caching or immediate handling is desired. If
> > ClientHello is cached, this will work with full ICE and will prevent
> > unverified media.
>
> If you are retransmitting ClientHello at 5 seconds, you are going to
> have a really bad time.  NSS is a tad aggressive, but our first
> retransmit is at 50ms (QUIC recommends 200ms I think).  Even TCP isn't
> that slow.  Packet loss happens and 5 seconds is well beyond the point
> that users give up.
>

I think 5 sec is default for opensips, but I might be wrong.

In general, I agree that caching is going to give better performance.
> We can recommend it, but I wouldn't mandate it.
>

I would suggest that we say that ClientHello may be cached, but DTLS
handshake MUST NOT start until answer is received.

Regards,
_____________
Roman Shpount

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