A SIP Usage for RELOAD

This document defines a SIP Usage for REsource LOcation And Discovery (RELOAD). The SIP Usage provides the functionality of a SIP proxy or registrar in a fully distributed system and includes a lookup service for Address of Records (AORs) stored in the overlay. It also defines Globally Routable User Agent URIs (GRUUs) that allow the registrations to map an AOR to a specific node reachable through the overlay. After such initial contact of a Peer, the RELOAD AppAttach method is used to establish a direct connection between nodes through which SIP messages are exchanged