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Interactive Connectivity Establishment (ICE) is a protocol for Network Address Translator (NAT) traversal for multimedia sessions established with the offer/answer model. ICE uses the Session Traversal Utilities for NAT (STUN) protocol and its extension that is, Traversal Using Relay NAT (TURN). ICE uses STUN and TURN servers to overcome network address translation issues that can occur when an endpoint is situated behind a NAT device. ICE solves the NAT issues for media streams. Support of the ICE specification is required by WebRTC (WRTC) endpoints. With the implementation of this feature, SBC acts

The SBC is capable of acting as an ICE-Lite agent . Therefore, to allow the endpoints using WRTC can be connected WRTC endpoints to connect to the existing VoIP network through the SBC by using the DTLS-SRTP protocol. While acting as an ICE-Lite endpoint, the SBC interconnects with endpoints that have either ICE-Lite or full-ICE implementations. ICE-Lite is a lite version of the ICE protocol, which is defined to exchange media with each other. The interconnect with ICE-Lite end points is only for the purpose of IPV4 IPv4 to IPV6 IPv6 inter-working and no NAT traversal procedures are supported for ICE-Lite to ICE-Lite.

Note

SBC implementation for ICE can be used with endpoints that are connected to the SBC through Sonus WRTC gateway and also WebRTC WRTC endpoints that are connected from some 3rd party WebRTC Gateway and present a third-party WRTC Gateway thereby presenting ICE in their SDP.

Note

As SBC is not required to act as an ICE client (it is not located behind a NAT in current deployment models), the initial support for ICE is limited to the SBC acting as an ICE-Lite endpoint.

The key points of ICE-Lite arekey points:

STUN message processing:

    • Decoding received messages on media port
    • .
    • Validating the received messages
    • .
    • Authenticating the received messages
    • .
    • Encoding outgoing STUN Response messages and sending on allocated media port
    • .
    • Encrypting outgoing STUN as per the configured username/password
    • .
    • An

Reachable IP address:  an ICE-Lite agent has a reachable public IP address and can work with other agents that use ICE and are behind the NAT.

ICE-Lite Implementation

The ICE-Lite procedure starts with the offerer discovering all the IP port where it is reachable. These are known as local “candidates”. The “candidates” can be any or all of the following:

...

The controlling agent sends an updated offer by using the selected local candidate in the default IP port of the media line and controlled agent (SBC) respond by sending its local candidate in the default IP port of the media line to complete the ICE-Lite procedure. The Ice-lite procedure can be restarted by the Full ice agent using ICE Restart procedures, if the Media ports changed during a call.