CODEWITHSUNDEEP
webrtc
batman
batman

Reputation: 5390

Does WebRTC allow actual peer-to-peer communication?

Is the signaling server used only the first time to establish a connection between 2 peers or is it also used to send and receive data-streams between the peers?

Upvotes: 1

Views: 112

Answers (2)

Lorenz Meyer
Lorenz Meyer

Reputation: 19945

This depends on the network configuration.

If at least one of the peers is not behind a NAT firewall, the peer that is directly on the internet acts as server, and the signalling server is no longer used after the connection is established.

If both peers are behind a NAT appliance, under certain circumstances it might be possible to negociate a client server connection between the peers, and the data is again sent directly between the two peers.

If both peers are behind a NAT firewall that is locked down, all the traffic between the peers passes through the signalling server.

Notice also that in the first two cases, a STUN server is used to establish the connection. If the full data is relayed through the server, a TURN server is used.

Look at a good explanation in the article an video on html5rocks. They claim only about 14% of all connexions need TURN, which seems a really low number to me (This corresponds to only 37% of all clients are behind a locked down NAT router).

Upvotes: 2

Trudbert
Trudbert

Reputation: 3198

According to the w3c proposal:

An RTCPeerConnection allows two users to communicate directly, browser to browser. Communications are coordinated via a signaling channel which is provided by unspecified means, but generally by a script in the page via the server, e.g. using XMLHttpRequest.

So the Server is only used for signalig not for data transmission. But signaling is not limited to establishing the first connection. The signaling channel is also used for transmitting error messages, metadata such as codecs, codec settings, networkdata and keys for secure transmission.

Upvotes: 3

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