WebRTC Data Channels use the Stream Control Transmission Protocol (SCTP) over a Datagram Transport Layer Security (DTLS) association. The standard SCTP connection establishment requires a handshake that introduces latency. A new Internet draft specifies a method to accelerate the datachannel establishment by embedding the SCTP initialization parameters within the Session Description Protocol (SDP) offer/answer exchange. This reduces the time required to open a data channel by up to two network round-trip times.
[RFC8831] defines WebRTC Data Channels that allow the transport of arbitrary non-media data over a WebRTC PeerConnection. This uses SCTP [RFC9260] and a DTLS encapsulation of SCTP packets [RFC8261]. SCTP establishes its associations using a four-way handshake, which primarily serves to protect against half-open (SYN-flood) attacks. For WebRTC, SCTP runs encapsulated within DTLS [RFC8261], which establishes a secure, encrypted channel between the peers that prevents half-open attacks. For WebRTC this handshake can be embedded into the SDP that is exchanged during Offer/Answer, eliminating two round trips from the connection setup.