February 14, 2011, 9:26 PM — Editor's note: This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.
Sometime this year the world will run out of Internet addresses doled out under the old-style IPv4 protocol, and while the 128 bit addresses in IPv6 will allow for essentially an unlimited number of addresses, the upgrade path is a tricky one.
[ See also: IPv6 basics: Getting started with IPv6 ]
For starters, the protocols are incompatible in a binary fashion. Network equipment designed to run IPv4 cannot effectively route IPv6 Internet traffic. IPv6 gear typically will be backward compatible and will be able to handle IPv4 packets; however translating packets from one world to the other is still not trivial.
That adds up to a backwards compatibility problem of epic proportions. Think of the impact of this in terms of broader network interoperability. The Internet community and its various providers of connectivity, transit, collocation, and other services, are far from monolithic. The whole Internet won't flip the switch one day and transfer everything to the IPv6 protocol. Guaranteed, in that awkward period of transition, connections will break. We've never made this big a switch.
Beyond compatibility, IPv6 will also give large swathes of the switching and routing infrastructure of the Internet a crushing performance downgrade. Many of the core, critical packet traffic cops use customized ASICs designed to accommodate IPv4 data streams. The manufacturers of these devices have given them the capability to support IPv6 by means of software upgrades. But purpose-built ASICs cannot be upgraded, so the tasks of routing will fall on the CPUs instead.
Further, the typical routing device does not tend to have a particularly powerful CPU. After all, that's what the ASIC is for, right? The result? Routing IPv6 traffic will dramatically reduce throughput speeds. Routers and cards that once ran on cruise control for days will begin to stagger under the increased performance requirements of IPv6. Your mileage may vary, but experts estimate performance declines of as much as 60% may loom.