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After more than a decade of forewarning, the IPv4 to IPv6 transition has finally reached critical mass. With broadband deployments achieving global exponential growth, next-generation wireless rollouts on the horizon, and smartphone use escalating, it is expected that there will be an increase of 5 bn unique endpoints between 2010 and 2015.
According to Gartner research, by 2015, 17% of internet users will use IPv6, and 28% of new internet connections will be running the protocol. Enterprises will need to create an IPv6 migration roadmap based on their need to communicate with endpoints, establishing IPv6 gateways no later than 2014, but not migrating their entire IT environments. Service providers are challenged to prepare their networks for the influx of IPv6 addresses.
As exemplified by Google's support of IPv6 on its search, news, docs, maps, and YouTube, the internet is already rich with IPv6 content and services; but IPv4 won't just vanish as IPv6 comes on board. This is not a transformation that can happen overnight; it's going to take time. In addition, the reality is that IPv4 and IPv6 will need to co-exist in a variety of environments for many years, adding further complexity to the already complicated transition.
While network cores are well-equipped to handle both IPv4 and IPv6, broadband access networks are not. IPv4 and IPv6 co-existence stresses the underlying network systems, which can introduce latency, degrade network responsiveness, and compromise service-level agreements (SLAs). The biggest transition concern is its impact on customers—will introducing IPv6 endpoints, forwarding tables, and services affect connectivity speed, service quality, and network reliability?
With fierce industry competitiveness over customer retention, service providers need assurance of a seamless IPv6 transition—at least from the customer perspective. To proactively address customer-impacting problems, service providers need a quick and reliable testing solution that enables them to predict the effect of the IPv6 transition on their broadband access network. It is also necessary to ensure that networks and associated devices (computers, smartphones, tablets, etc.) and applications correctly interact when both IPv4 and IPv6 are used simultaneously.
A successful transition from IPv4 to IPv6 is built on the foundation of proper testing for interoperability in real-world conditions—with real-world devices, real-world networks, and real-world traffic.
An abrupt transition of the legacy IPv4 infrastructure to IPv6 is not practical because most internet services are still based on IPv4 and many customers still run operating systems that do not fully support IPv6. Service providers must support both IPv4 and IPv6 endpoints and services to guarantee the quality of service (QoS) defined in their SLAs.
There are different methods used to achieve this goal across broadband access networks including:
- Translation
- Tunneling (includes dual-stack lite and IPv6 rapid deployment)
- Dual-stack
Translation
The easiest way to conserve the depleting IPv4 address space is to use translation so that the outward-facing interface uses a public interface while the private network uses IP addresses that are not routed on the internet. However, known performance and scalability issues can force service providers to deploy tunneling or dual-stack transition mechanisms.
Tunneling
Tunneling mechanisms are used to tunnel IPv6 island traffic over IPv4 networks and vice versa. The two tunneling schemes currently receiving significant industry attention are:
- Dual-Stack Lite (DS-Lite): While service providers aim to capitalize on the benefits of quickly embracing IPv6, they must also contain the costs of doing so and ensure uninterrupted IPv4 support. With DS-Lite, broadband service providers handle IPv4 addresses using IP in IP (IPv4-in-IPv6) tunneling and Network Address Translation (NAT). DS-Lite simplifies the IPv4/IPv6 transition by de-coupling IPv6 deployment in the service provider network from the rest of the internet.
- IPv6 Rapid Deployment (6rd): In order to quickly offer end-to-end IPv6 service, providers can use 6rd to encapsulate IPv6 traffic in IPv4 headers, and tunnel home users' IPv6 traffic through the IPv4 network to IPv6 internet services. This tunnel is terminated by an edge router on the service provider network and native IPv6 packets are then transmitted to the IPv6-capable internet. This allows for rapid introduction of IPv6 services in provider networks as they transition from IPv4 to IPv6.
This approach minimizes deployment costs because it only requires upgrades to the routers at the customer edge (CE routers) to support 6rd and additional border routers (BR) that terminate the tunnel.
Dual-Stack
Many service providers plan to deploy dual-stack networks as a long-term strategy, supporting a mixture of IPv4 and IPv6 applications for customers that require both protocols. Dual-stack-capable devices support both IPv4 and IPv6, from the network layer to the applications. Applications choose to use either IPv4 or IPv6 based on the type of IP traffic and particular requirements of the communication.
Test Requirements
To offer customers a seamless IPv6 transition, service providers must ensure services can be delivered with requisite quality guarantees. Network design and configuration requires protocol and traffic stress-testing to identify the scalability limits of each device.
It is equally important to validate interoperability of the different network devices, especially given the compatibility risks between IPv4 and IPv6 devices. Test equipment plays a critical role in this validation as it enables reliable, repeatable measurements across network devices.
Test equipment is used to emulate the customer premises and home devices, as well as the internet services, surrounding each broadband network device under test (DUT). This allows service providers to test network equipment under real-world scenarios without the time and expense of building extensive test beds of real equipment.
Conclusion
With IPv4 address depletion, IPv6 applications and endpoints will soon become ubiquitous across networks from end to end. To ensure this evolution is transparent to subscribers, service providers, and network equipment vendors must demonstrate that the network infrastructure equipment is ready for IPv4/IPv6 co-existence.
Michael Haugh
The author is senior market development manager, Ixia
vadmail@cybermedia.co.in