How could webRTC works without peerConstraints?

General
1

Hi Folks,
I’m new to webRTC and React-Native.
Although, from the code of Geoff Chen GitHub - geoffcfchen/webRTC-react-native-firebase-expo, I succeeded to create an app which works in my local network.

Of couse, if i keep one device on the local network, and set the other device on 4G network, it stops to work… …so I’m planning to deploy a coturn docker container soon.

Nevertheless, there is something I dont understand…

In the code, we are setting peerConstrainf to :

export const peerConstraints = {
  iceServers: [
    {
      urls: [
        "stun:stun.l.google.com:19302",
        "stun:stun1.l.google.com:19302",
        "stun:stun2.l.google.com:19302",
      ],
    },
  ],
  iceCandidatePoolSize: 10,
};

and call it while setting up the webRTC layer by :

pc.current = new RTCPeerConnection(peerConstraints);

Everything is fine…
Although, if I do :

pc.current = new RTCPeerConnection();

Everything still works (while on local network)

I dont understand why ?

Can someone explain it to me ?

Best Regards,
Edouard

2

By default WebRTC will connect to any internal/external addresses as long as they are accessible.
When using STUN/TURN servers you are usually targeting external networking.
But as things go, a lot of networks tend to implement the use of a NAT.
Which then means you’d need a STUN/TURN server to accomplish a stable connection.

1 Like
3

Thank you so much for your answer ! So actually, if both are on my local network, you mean that not even the STUN server is reached ? …sorry to confirm, just, i’m really new to this… :wink:

4

If both devices are on your local network and you don’t have any weird network setup/conditions then you can use WebRTC internally without the requirement of a STUN/TURN server.
It only becomes complex and unstable when trying to connect externally or if you have a bit of a restrictive network. For example, some wireless networks have client isolation enabled which means devices will only get internet access but can’t connect to each other.

5

Thanks for your answer… …in fact you help me both on the discourse and the github… Cool Buddy !! :wink:

1 Like
6

No worries, you’re welcome :slight_smile: