Webrtc series - 7-ice supplement of network transmission preference and priority

1. ice Preferences in preference

stay RFC 5245 Document 4.1.2.2 There is a section on guidelines for selecting types and local preferences in . It mainly introduces several cases of ice Guidance on setting preferences ：

1. When considering the traffic consumption and delay of media services during transit ： Relay waiting (relayed candidates) The type preference of the candidate should be lower than that of the host candidate (host candidates), Recommended values :
   • 126 Used for host candidate (host candidates),
   • 100 Used for server reflection candidates ( server reflexive candidates),
   • 10 For peer-to-peer reflection candidates (peer reflexive candidates),
   • 0 Used to relay candidates .
   • If the proxy is multihomed and has multiple IP Address , It comes from VPN The local priority of the host candidate for the interface should have priority 0.
2. Another criterion is IP Address family ： Basically is IPV6>IPV6ToIPV4>IPV4, This is mainly for the host to quickly support IPv6 Host communication for , At the same time, it does not support IPv6 The host can quickly fall back to ipv4;
3. Another criterion is safety ： That is to say VPN Have a high preference

stay webrtc The use of in is to determine preferences by default based on the possibility of negotiation with the opposite end , That is, according to the conditions 1, The default is ：