WebRTC Architecture

This article covers the major components used in a WebRTC deployment.

Please note that the article assumes you have a basic understanding of WebRTC. Consider reading trough the WebRTC Introduction if you are new to WebRTC.

Signaling server

The first step in setting up a WebRTC connection is what’s known as signaling. This is en exchange of information needed to safely connect two peers to each other. The WebRTC API provides this data in a plain text a format known as SDP. It is up to the user to safely exchange this information between the two peers who want to establish a connection.

WebRTC deployments commonly use what’s known as a signaling server to accomplish this task. This server usually consists of a HTTPS or Secure WebSocket server tasked with exchanging the signaling information between the correct peers.

The Pion family doesn’t contain an of-the-shelf signaling server yet. However, there is an example implementation available under the pion/signaler repository.

STUN Server

As the name suggests a STUN server is a server that speaks the STUN protocol. This server allows a peer to discover it’s own public IP address. This IP address is sent to the remote peer during the signaling step in order to establish the peer to peer connection.

A STUN server has low resource requirements. Because of this there are public STUN servers available. However, it is not recommend to rely on a public STUN server for production use.

The Pion TURN server can be configured to act as a STUN server specifically.

TURN Server

As the name suggests a TURN server is a server that speaks the TURN protocol. This server is used to relay WebRTC traffic around a strict NAT or firewall. This server is used as a fallback in case the WebRTC protocol can’t find another way to connect two peers. A TURN server is not required in order to setup a WebRTC connection. However, it does enable a broader spectrum of users to use your WebRTC enabled application. It is often users behind strict corporate NAT/firewalls that require a TURN server in order to make a WebRTC connection.

A TURN server usually has high bandwidth requirements since it has to forward all the data send over a WebRTC connection. Because of this there are little to no public TURN servers available. You can rent a TURN server or set-up your own. Most TURN servers also act as a STUN server.

The Pion TURN Server can be found under the pion/turn repository.

Media server

A media server refers to any server that does server side processing on the WebRTC media. This processing can take many forms, including: routing, mixing, recording and transcoding.

The Pion Media Server can be found under the pion/media-server repository.