The steadily increasing penetration of broadband
Internet access and the proliferation of free mobile Over-the
Top (OTT) voice and video applications are driving the rapid
adoption of voice over Internet Protocol (VoIP). For both
consumer and business markets, it is securing a position as the
main mode of multimedia communication.
High quality multimedia communications, rich
presence, and lower costs are just some of the benefits VoIP
brings to end-users. For operators, it promises revenue streams
from new and converged services, increased customer loyalty
through extending the service value proposition, and lower
capital and operation expenses (capex/opex) through utilizing
single IP-based networks for all communications services.
Ironically, one of the main driving forces
behind VoIP adoption also poses one of its biggest challenges -
VoIP calls do not work well in many broadband and mobile
situations. The problem stems from two common network elements:
NAT - More than 90% of wired and
mobile devices access broadband networks using private
(internal) IP addresses. These private IP addresses get
mapped, or translated, into publicly routable, external
Internet addresses using a mechanism called Network Address
Translation (NAT). NAT is implemented in all broadband
access devices (routers), and sometimes again in the service
Firewalls - Most users have one or
more packet-filtering firewalls protecting them from hackers
and other malicious users on the Internet. Firewall features
are implemented into most routers and directly in many of
the popular operating systems from providers such as
Microsoft, Apple, and others.
Many VoIP solutions, peer-to-peer file sharing
applications, and gaming consoles on the market do not work well
through NATs and firewalls - endpoints may fail to connect to
each other, or the quality and performance may be unacceptable.
NAT traversal is the general term for a variety of techniques
used to overcome the connectivity challenges posed by NATs.
One widely deployed and trusted NAT traversal
technique utilizes the IETF standards Interactive Connectivity
5245), combined with Session Traversal Utilities for NAT
5389), and Traversal Using Relay NAT (TURN,
5766). This paper explores NAT traversal using ICE, STUN,
and TURN further in sections 3 and 4.
The transition to IPv6, in theory promises to
eliminate the need for NAT in the future due to the abundance of
new routable IP addresses available within the IPv6 schema.
However in reality, IPv6 will create transition related issues
that will affect VoIP and video chat technologies in the short
to mid term.
This white paper explores the root causes and
challenges of the NAT traversal and firewall traversal problem
for VoIP and video telephony applications, peer-to-peer file
transfer and other applications requiring end-to-end
connectivity. It summarizes recent work and progress made by
standards-bodies and the industry on NAT traversal, and,
finally, presents a comprehensive solution to this problem
comprising a client-side SDK and a scalable carrier-grade
NATs and Firewalls break VoIP and IP Communication