Webrtc Intro - SCTP

SCTP stands for Stream Control Transmission Protocol.

SCTP as a protocol can be seen as a hybrid of UDP and TCP.

At its core, SCTP holds the following characteristics:

• Connection oriented. Similar to TCP, SCTP is connection oriented. It also offers a multi-homing capability that isn’t used by WebRTC
• Optional reliability. Reliability is optional in SCTP and is up to the implementer using SCTP to decide if he needs this capability or not
• Optional ordering. Ordering of packets sent via SCTP is optional and is left for the implementer to decide if this is necessary for him or not
• Message oriented. SCTP makes sure that each message sent is properly parsed on the receiver end in the same manner in which it was sent
• Flow control. Similar to TCP, SCTP provides a flow control mechanism that makes sure the network doesn’t get congested

SCTP is not implemented by all operating systems. In such cases, an application level implementation of SCTP will usually be used.

SCTP is used in WebRTC for the implementation and delivery of the Data Channel.

Google is experimenting with the QUIC protocol as a future replacement to SCTP.

QUIC stands for Quick UDP Internet Connections.

QUIC is an experimental protocol by Google that is based on UDP and targeted at improving situations when you need multiple parallel sessions between two entities. This is the situation for virtually every web page on the internet, which usually requires more than a single resource file to be transmitted from the web server to the browser.

QUIC finds WebRTC in Google’s latest roadmap where it announced its intentions to experiment with the use of QUIC as a replacement for SCTP for the data channel transport.