Re: [rtcweb] DTLS, DTLS-SRTP, and 5-tuples

[Roman Shpount <[e-mail]>]

On Wed, Mar 4, 2015 at 7:44 PM, Iñaki Baz Castillo <[e-mail]> wrote:

> Take into account that when aggressive ICE nomination is being done, a
> peer sends multiple STUN requests with USE-CANDIDATE at the same time
> and DTLS ClientHello after each of them. At the end this means that
> the receiver must be ready to receive DTLS packets via different
> 5-tuples at the same time, all of them belonging to the same DTLS
> association/connection.
>

I am not sure this is entirely correct.  My assumption was that during
aggressive ICE nomination, an end point will send DTLS ClientHello over the
first candidate pair where ICE connectivity check succeeds. The end point
should be ready to receive DTLS messages over any ICE candidate pair. If
end point does not receive response to DTLS ClientHello it should
re-transmit ClientHello over the highest priority ICE candidate pair at the
time of the re-transmission. I do not think there is any need to send
multiple DTLS ClientHello messages at the same time over multiple candidate
pairs. In other words, an end point should treat ICE as a single virtual
channel, where data is transmitted over the highest priority ICE candidate
pair for which the connectivity check succeeded and process data received
from any non-pruned ICE candidate pair. There is no need to trombone the
data over all the candidate pairs when it is being sent out. This should
fit nicely with existing DTLS implementations.
_____________
Roman Shpount