Today, the Internet Assigned Numbers Authority ( IANA) will be passing out the last five Class A address spaces to the Regional Internet Registries (RIR), which in turn allocate IP addresses to organizations within their specific geographic regions. This marks the end of the IPv4 central pool, and the countdown to IPv4 exhaustion begins in earnest. The American Registry of Internet Numbers (ARIN)--which handles allocations for Canada, the United States and many Caribbean islands--is forecasting that it will run out of address space in the July-to-October time frame.
Other RIRs may exhaust their IPv4 address space sooner or later, depending on their regional demands. However, IPv4 exhaustion is not a cause for panic--the Internet will not fail. In fact, you may hardly notice the event horizon. However, it is time to start planning your IPv4-to-IPv6 migration. Notably, John Curran, CEO of ARIN, notes that ARIN is starting to see service providers requesting IPv6 address blocks sooner and more frequently.
When an organization requests an address block, it has to justify the request and demonstrate that it is using the addresses that it has already been assigned. This helps to manage the available address pool more effectively. ARIN uses a number of methods to verify the justifications, but the process can take time. Curran says service providers are requesting new IPv6 blocks sooner in an attempt to have address space to meet demand for their existing and new customers.
The initial impact most organizations will see with IPv4 exhaustion is turning up new services on the Internet. As the address space is exhausted, organizations, service providers, hosting providers and cloud providers will have to develop strategies to support both IPv6 users and services and IPv4 users and services. Some of those strategies include running dual-stack IPv4 and IPv6 hosts and networks, performing IPv6-to-IPv4 translation, tunneling and the use of proxy servers to facilitate a migration to the new address space as software allows. One IT admin who wished to remain anonymous notes, "We have done this before with [Novell's] IPX to IP. It's not going to be a big deal. There will be bumps along the road. But we'll get over it."
While migrating from one addressing system to a new one may be old-hat to some, there is the potential for applications such as SIP, FTP, gaming protocols and peer-to-peer protocols (which use dynamic address and port assignments encapsulated in a the protocols control channel) to be adversely affected. The problem is that for complex protocols to survive a translation, some device, which is usually the nearest router, has to be protocol-aware and translate not only the IP addresses in the packets, but also the IP addresses residing inside the protocols. Waiting for these application-level gateways to be developed could cause service disruptions while service providers transition to IPv6 and equipment vendors catch up with software updates.