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Network Address Translation (NAT) Solution Brief

Traditional NAT, Emerging NAT Standards and Related Technologies

In the past two decades, IP networks have evolved and the number of IP-enabled devices soared at a tremendous pace. Globally unique IPv4 addresses are in great demand and IPv4 address exhaustion has been observed since the mid-1990s. NAT (Network Address Translation) became a popular tool for alleviating the IPv4 address exhaustion.

However, many experts predict that the supply of available IPv4 addresses will run out sometime between 2011 and 2013, while at the same time we are starting to see much more interest in IPv6 due to strong Mobile IP support. Many people acknowledge that even if they implement IPv6, they still need to communicate with the existing IPv4 world, even if that entails more complexity and compromises. There are several new competing NAT technologies to address the coexistence of IPv4 and IPv6 networks: Large Scale NAT (LSN), Dual-Stack Lite (DS-Lite) and NAT-PT with DNS-ALG.

Traditional NAT

The solution to this challenge has been NAT (Network Address Translation). NAT has enabled one single external IP address to represent, and effectively be shared by, multiple internal hosts. There are two traditional flavors of NAT predominantly used today:

Both types of devices are referred to as NAT devices, and the most popular implementations are NAPT devices. These devices translate both the IP addresses and TCP/UDP port numbers (or ICMP identifiers) from the internal network to the external network and back.

The Issues with Traditional NAT

The introduction of NAT devices in a network has also become a major source of problems for network users and administrators. NAT devices have not been truly transparent when introduced in a network. Traditional NAT works well for traditional client-to-server applications, where a client opens a connection to a server and requests data, and the server responds back to the client.

However, many of the popular applications in the present day such as peer-to-peer (P2P), instant messaging (IM), voice-over-IP (VoIP) and others are client-to-client applications, and such applications do not typically work well in networks with NAT devices. Based on NAT behavior, certain applications (for example some AJAX based applications), which open multiple sessions to the same or multiple servers, also do not work as advertised, or at all.

Solution with Advanced NAT Technologies

The A10 solution is to use new and emerging technologies, which are being developed to combat the issues of traditional NAT today. Although IPv6 is an option, networks are currently IPv4-centric, with IPv6 deployment progressing slowly. Intermediate technologies to improve NAT efficiency and scale networks include:

Large Scale NAT (LSN) also known as Carrier Grade NAT (CGN)

Dual-Stack Lite (DS-Lite)

Transition to IPv6 with NAT-PT with DNS-ALG

IPv6 eliminates the need for NAT, due to removing the scarcity of IP addresses, but still has limited deployments. However, strategically, organizations are increasingly requiring IPv6 administration and IPv6 traffic management capabilities. IPv6 vendor commitment and support allow flexibility to ensure an appliance will not be obsolete.

IPv6 deployments will be accelerated through features that allow easier adoption. NAT-PT, with the PT standing for Protocol Translation, is an example. This innovative technology allows incompatible IPv4-and IPv6-based computing devices, whether client or server, to communicate. A10's AX Series Advanced Traffic Manager provides the protocol translation. Key AX capabilities include:

Full IPv6 support

NAT-PT with DNS-ALG

Translation Server Load Balancer (v6-v4 SLB or v4 -v6 SLB)

High Performance NAT Platform

A10's AX Series Advanced Traffic Managers are specifically built for processor-intensive, high volume networking tasks, such as NAT. The AX Series includes the Advanced Core Operating System (ACOS), which integrates modern multi-core, multi-threaded software to provide significant performance advantages. The AX Series includes:

Industry-leading performance is achieved via leveraging Flexible ASIC enhanced Symmetric Multiprocessing (SMP) technologies. The AX Series processes application traffic in parallel fashion, without the need to copy data or replicate computing instructions. As a result, these applications run faster with the AX Series than with competing systems on the market today.

Continuing Market Leading Innovation

The AX Series is a unique platform for high performance network computing, lending itself to processor-intensive functions at the largest scale. For advanced NAT and other transition technologies, contact A10 for an evaluation.



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