Hurricane Electric, the world’s largest IPv6-native Internet backbone and leading colocation provider, announced today that its Director of Professional Services and IPv6 Evangelist, Owen DeLong, has issued a warning about the underestimated costs of Carrier Grade NAT (CGN).
Mr. DeLong argues that the most common stopgap solution to the IPv4 address-space exhaustion problem – CGN – has costs greater than its adherents are willing to admit. By further damaging the end-to-end addressability paradigm inherent in the Internet Protocol, CGN slows innovation, breaks certain applications (and makes others needlessly complex) and can increase communications latency.
Mr. DeLong begins his admonition by comparing the existing IPv4 address space to an undersized parking lot for a restaurant. Continuing the metaphor, DeLong compares NAT (Network Address Translation) to valet parking, in which the illusion of unlimited space comes at the cost of maintaining a complex translation table of customers, keys and distant parking places - and long waits at the valet kiosk.
DeLong discusses CGN’s “significant challenges,” which include breaking peer-to-peer applications (e.g., VOIP, multi-player online games, and some forms of instant messaging) and hampering law enforcement, civil litigation, and geo-location capabilities. DeLong also discusses performance problems introduced by NAT Control Points (“NAT Centers”), which can introduce significantly longer routing paths of data packets. Furthermore, DeLong describes the lack of scalability in CGN, showing that neither port-map logging nor the workaround of pre-assigned port ranges scales.
“The question of whether CGN is an effective - or even a viable - alternative to IPv6 has not been given careful enough consideration,” said Owen DeLong, Director of Professional Services at Hurricane Electric.
DeLong states that the primary impediment to IPv6 adoption is that the benefits of CGN accrue to the service provider, but that the costs of CGN fall to the subscriber. For the service provider, it is cheaper to train staff about CGN than IPv6, and it is initially less expensive to roll out CGN gateways than to roll out IPv6 to all subscribers. But in the long term, both subscribers and providers suffer from the reduced innovation, decreased throughput, and reduced application reliability and functionality that result from CGN.