Re: [TLS] Stopping retransmission DTLS 1.2

Hi Simon,

In case of partial read, after retransmit timeout if a DTLS receiver doesn’t retransmits then peer will retransmit its flight again only if it is not the final flight.

Consider a receiver is DTLS client, and peer (server) is sending its final flight (CCS and FM). If any one of the message is not received, then client has to retransmit its previous flight (CKE, CCS and FM) otherwise server wont retransmit its message.

Regards,

Ashok

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Raja Ashok V K
Huawei Technologies
Bangalore, India
http://www.huawei.com
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-----Original Message-----
From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Simon Bernard
Sent: 31 May 2017 22:06
To: tls@ietf.org
Subject: [TLS] Stopping retransmission DTLS 1.2

Hi,

    The RFC6347, 4.2.4 [1] say :

         "3. The implementation receives the next flight of messages: if this

         is the final flight of messages, the implementation transitions to

         FINISHED. If the implementation needs to send a new flight, it

         transitions to the PREPARING state. Partial reads (whether

         partial messages or only some of the messages in the flight) do

         not cause state transitions or timer resets."

    I would like to know why "partial reads do not cause state timer resets".

    I mean if we receive the first "handshake message" of the expected "flight". we can assume that the foreign peer received our previous flight and so we can stop retransmissions of this flight.

    If the next message is lost, we will never respond and so the foreign peer should retransmit the whole flight. We don't need to retransmit on our side, so timer should be reset ?

    Did I missed something ?

Thx.

Simon

[1]https://tools.ietf.org/html/rfc6347#section-4.2.4

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Re: [TLS] Stopping retransmission DTLS 1.2

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