Interactive Connectivity Establishment

Abstract: If a host is located behind a NAT, then in certain situations it can be impossible for that host to communicate directly with other hosts (peers). In these situations, it is necessary for the host to use the services of an intermediate node that acts as a communication relay. This specification defines a protocol, called TURN (Traversal Using Relays around NAT), that allows the host to control the operation of the relay and to exchange packets with its peers using the relay. TURN differs from some other relay control protocols in that it allows a client to communicate with multiple peers using a single relay address. [STANDARDS-TRACK]

Abstract: This document describes a protocol for Network Address Translator (NAT) traversal for UDP-based communication. This protocol is called Interactive Connectivity Establishment (ICE). ICE makes use of the Session Traversal Utilities for NAT (STUN) protocol and its extension, Traversal Using Relay NAT (TURN). This document obsoletes RFC 5245.

Abstract: For a long time, traditional client-server communication was the predominant communication paradigm of the Internet. Network address translation devices emerged to help with the limited availability of IP addresses and were designed with the hypothesis of asymmetric connection establishment in mind. But with the growing success of peer-to-peer applications, this assumption is no longer true. Consequently network address translation traversal became a field of intensive research and standardization for enabling efficient operation of new services. This article provides a comprehensive overview of NAT and introduces established NAT traversal techniques. A new categorization of applications into four NAT traversal service categories helps to determine applicable techniques for NAT traversal. The interactive connectivity establishment framework is categorized, and a new framework is introduced that addresses scenarios that are not supported by ICE. Current results from a field test on NAT behavior and the success ratio of NAT traversal techniques support the feasibility of this classification.

Abstract: An endpoint uses Interactive Connectivity Establishment (ICE) to enable multimedia communications to traverse Network Address Translators (NATs). A security policy enables security devices and asymmetric security devices to forward ICE messages. A management device stores information about an initial message. Later, a security device receives an ICE message and sends and authorization request to the management device. The management device compares information in the authorization request to information in memory. According to the comparison, the management device authorizes the security device to forward the ICE message.