WebRTC (Web Real-Time Communication) is a browser-side real-time communication technology that can realize real-time transmission of various data such as video, audio, and text. Network Address Translation (NAT) is a common problem in WebRTC because many devices are behind private networks and not directly accessible. The main way to solve the NAT problem is to use the ICE (Interactive Connectivity Establishment) protocol. Below we will introduce several NAT traversal schemes in WebRTC.
- ICE-Lite Solution
The ICE-Lite solution is a simplified version of the ICE protocol, which aims to reduce network bandwidth consumption and delay by simplifying STUN/TURN protocol interaction. In ICE-Lite scenario, when WebRTC client is behind NAT, it will only use STUN server, not TURN server. The simplified protocol means that ICE-Lite clients do not send and receive STUN/TURN interaction messages like ICE Full clients, reducing communication overhead and latency. However, because ICE-Lite can only use the STUN server for NAT penetration, if the STUN server cannot successfully obtain the client's public network IP address and port number, then ICE-Lite cannot establish a P2P connection in this case.
- ICE-Full scheme
The ICE-Full scheme is a NAT traversal scheme commonly used in WebRTC. After using the ICE-Full scheme, both communicating parties can obtain each other's IP address and port number, and use this information to open the corresponding port in the NAT firewall, thereby realizing P2P transmission. The ICE-Full solution needs to obtain NAT type and public network address information through the STUN server, and then relay through the TURN server to ensure that NAT can be successfully penetrated in various network environments.
- ICE-TCP scheme
ICE-TCP is a NAT traversal scheme based on TCP protocol. It is similar to ICE-UDP, but uses TCP as the underlying transport protocol. ICE-TCP is suitable for situations where UDP is disabled or there is a high rate of packet loss.
- SIP/TLS scheme
SIP (Session Initiation Protocol) over Transport Layer Security (TLS) is a secure NAT traversal scheme. It uses TLS protocol to establish a secure communication link, and establishes point-to-point communication between two devices through SIP protocol, avoiding NAT problems.
- TURN scheme
Traversal Using Relay NAT (TURN) is a NAT traversal scheme, which relays data traffic through a relay server, so that two devices can also perform P2P communication in a NAT environment. The disadvantage of the TURN solution is that the delay is relatively large, it needs to rely on the server, and the cost is relatively high.
- STUN scheme
Session Traversal Utilities for NAT (STUN) is a NAT traversal protocol, which allows WebRTC clients to obtain their own public IP address and port number behind NAT, and implement P2P communication through these information.
In short, the above are some common NAT traversal scheme modes, and the selection of different schemes depends on the actual application environment and requirements. In the actual development process, we can choose an appropriate NAT penetration solution according to specific needs to ensure the normal operation of WebRTC.
WebRTC supports the following ICE schemes:
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ICE-Lite: ICE-Lite is a simplified version of the ICE protocol. In this scheme, the client only uses the STUN server and does not use the TURN server, which can reduce network bandwidth consumption and delay.
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ICE-Full: ICE-Full is a NAT penetration scheme commonly used in WebRTC. After using the ICE-Full scheme, both communicating parties can obtain the other party's IP address and port number, and use this information to open the corresponding port in the NAT firewall, thereby realizing P2P transmission. The ICE-Full solution needs to obtain NAT type and public network address information through the STUN server, and then relay through the TURN server to ensure that NAT can be successfully penetrated in various network environments.
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ICE-TCP: ICE-TCP is a NAT traversal scheme based on the TCP protocol. Similar to ICE-UDP, but uses TCP as the underlying transport protocol. ICE-TCP is suitable for situations where UDP is disabled or there is a high packet loss rate.
To sum up, WebRTC supports a variety of ICE solutions, and choosing an appropriate solution can improve the quality and efficiency of communication. In practice, we can choose the most suitable solution according to specific needs.