RTCIceCandidate: protocol property

{{APIRef("WebRTC")}}

The {{domxref("RTCIceCandidate")}} interface's read-only protocol property is a string which indicates whether the candidate uses {{Glossary("UDP")}} or {{Glossary("TCP")}} as its transport protocol.

The protocol field's value is set from the candidateInfo options object passed to the {{domxref("RTCIceCandidate.RTCIceCandidate", "RTCIceCandidate()")}} constructor. You can't specify the value of protocol directly in the options object, but its value is automatically extracted from the object's candidate a-line, if it's formatted properly.

protocol is null by default if not specified properly in the SDP, but this is an error condition and will result in a thrown exception when you call {{domxref("RTCPeerConnection.addIceCandidate()")}}.

Value

A string that indicates what network protocol the candidate uses:

• tcp
  • : The candidate, if selected, would use {{Glossary("TCP")}} as the transport protocol for its data. The {{domxref("RTCIceCandidate.tcpType", "tcpType")}} property provides additional information about the kind of TCP candidate represented by the object.
• udp
  • : The candidate will use the {{Glossary("UDP")}} transport protocol for its data. This is the preferred protocol for media interactions because of its better performance profile.

[!NOTE] If protocol is null — and protocol is supported by the {{Glossary("user agent")}} — passing the candidate to {{domxref("RTCPeerConnection.addIceCandidate", "addIceCandidate()")}} will fail, throwing an OperationError exception.

Usage notes

Here's an example candidate a-line from an ICE transaction:

a=candidate:4234997325 1 udp 2043278322 192.0.2.172 44323 typ host

The third field, "udp", is the protocol type, indicating that the candidate would use the UDP transport protocol.

Examples

This code snippet examines the value of protocol to decide if it should look at the value of {{domxref("RTCIceCandidate.tcpType", "tcpType")}} to see if it's a simultaneous-open (S-O) candidate.

if (candidate.protocol === "tcp") {
  if (candidate.tcpType === "so") {
    adjustForSimultaneousOpen(candidate);
  }
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}