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Because of the constant reduction of available public network addresses and the necessity to secure networks, middleboxes such as network address translators and firewalls have become quite common. Because they are designed around the client-server paradigm, they break connectivity when protocols based on different paradigms are used (e.g., VoIP or P2P(More)
— Although the SIP protocol claims a complete dual-stack support, some aspects, such as interoperability between different address realms and support for multi-homed hosts, are not taken into consideration. This leads to an extensive usage of proxies as gateways, e.g., between different address realms. ALEX (" Address List Extension ") is a simple extension(More)
The successful and increasingly adopted session initiation protocol (SIP) does not adequately support hosts with multiple network addresses, such as dual-stack (IPv4-IPv6) or IPv6 multi-homed devices. This paper presents the Address List Extension (ALEX) to SIP that adds effective support to systems with multiple addresses, such as dual-stack hosts or(More)
The wide diusion of NATs (and, in some respect, rewalls) may prevent some applications that require direct end-to-end connectivity (e.g., real-time media) from being able to connect to the remote party. While the solutions currently adopted rely on centralized nodes as third party relays, the DISCOS architecture has been recently proposed and aims at(More)
Because of the constant reduction of available public network addresses and the necessity to secure networks, middleboxes such as network address translators and firewalls have become quite common. Because they are designed around the client-server paradigm, they break connectivity when protocols based on different paradigms are used (e.g., VoIP or P2P(More)
While peer-to-peer networks are mainly used to locate unique resources across the Internet, new interesting deployment scenarios are emerging. Particularly, some applications (e.g., VoIP) are proposing the creation of overlays for the localization of services based on equivalent servants (e.g., voice relays). This paper explores the possible overlay(More)
— The widespread diffusion of private networks in SOHO scenarios is fostering an increased deployment of Network Address Translators (NATs). The presence of NATs seriously limits end-to-end connectivity and prevents protocols like the Session Initiation Protocol (SIP) from working properly. This document shows how the Address List Extension (ALEX), which(More)
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