Session initiation and maintenance while roaming

Abstract

The technology disclosed addresses initiation of peer-to-peer media exchange sessions, with traversal of NAT and firewall devices, in a manner adapted to roaming. In particular, involves preliminary determination of NAT/firewall topology, which reduces latency at initiation, and hole punching technologies to select a routing and traversal strategy that reduce reliance on external media relay devices.

1 . A method of resolving NAT and firewall related issues for initiation of a session, the method including:
 determining NAT/firewall topology by sending two or more messages from the initiating peer device by an unreliable transport protocol through one or more NAT and firewall devices to two or more external IP/port addresses, listening for responses, and determining from the responses or lack of responses whether the firewall will allow initiation of unreliable transport protocol sessions or determining whether the NAT assigns IP/port addresses to the messages that are predictable by the initiating peer device;   sending one or more probe messages through the one or more NAT and firewall devices to an external server or a network controller, listening for responses and identifying from the responses one or more external IP/port addresses assigned by the NAT to the one or more probe messages;   proceeding with an exchange of session initiation messages, wherein a session initiation message from the initiating peer device includes, at least an internal, inside the NAT, IP/port address and the external IP/port addresses for the initiating peer device;   using at least results of the determining NAT/firewall topology, selecting potentially successful hole punching strategies and commencing, if selected, hole punching to establish a transport session between the initiating and responding peer device.