Raise Your PC IQ! 6 Key Technologies Explained

Posted 12/06/2010 at 6:19pm | by The Maximum PC Staff

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Internal Protocol Version 6

How the next-generation Internet protocol, IPv6, will save the day by increasing the number of available addresses and adding new features

Are you prepared for the next Y2K? We’ve dubbed it “The Great IP Address Shortage of 2011—or Shortly Thereafter.” While “TGIPAS2011oST” doesn’t roll off the tongue as easily as “Y2K,” this creeping calamity could cause fundamental networking problems the day someone claims the very last public IPv4 (Internet Protocol version 4) address.

Fortunately, a solution is already here: IPv6 (Internet Protocol version 6), will create trillions (times trillions times trillions) more public addresses while introducing new networking features. Both IP technologies will coexist during the transition, so in many cases, IPv6 devices will switch to an IPv4 mode to communicate with old gear.

We’ll explain the basics of how Internet layers shuffle information across worldwide networks. Then we’ll discuss the changes and improvements in IPv6; it’s about more than adding addresses. With these details, you’ll be able to prepare for the dual-stack, hybrid near-future and the eventual transition to IPv6 exclusivity.

Peeling Back the Layers

The Internet uses four main layers to transmit data. You might think of them as nesting matryoshka dolls, with each layer in the progression encapsulating the next. (You can read more about this topic here.)

The Link Layer includes the hardware and software (or firmware) to handle the lowest level of communications, including Media Access Control (MAC). (While some define hardware connections as part of the Physical Layer below this, we’ll side with those who combine the two.) The Internet Layer rides on top of that, consisting largely of IPv4 or IPv6. The Transport Layer transmits and delivers data to specific application protocols residing in the Application Layer, including HTTP (Hypertext Transfer Protocol) and FTP (File Transfer Protocol).

The Internet Layer is especially important since you’ll sometimes set its addressing while configuring network equipment, such as a router. More often, the other layers are invisible to end-users; things just work.

Change of Address

A new addressing method marks the biggest change between IPv4 and IPv6. IPv4 technology uses 32-bit addresses that allow about 4 billion possible public nodes. Due to growing demand and inefficient allocation of existing IP addresses, the planet has consumed nearly all of these. Estimates vary as to exactly when we’ll run out of IPv4 addresses, but most experts anticipate it happening soon.

IPv6 solves the problem in a big way. It uses a 128-bit addressing scheme that creates 2128 possible combinations: roughly 34 trillion trillion trillion (34 followed by 37 zeroes) IP addresses—enough to support every Internet connected computer, phone, television, gaming console, refrigerator, and toaster humanity could ever want. Here’s an example of what an IPv6 address looks like: 2001:0DB8:AC10:2F3B:9C5A:FFFF:3FFE:02AA.

Since IPv4 and IPv6 will coexist for a time, IPv6 nodes will communicate with each other via tunnels through IPv4-only infrastructures using so-called "6to4" technology. This will enable devices (hosts, routers, etc.) with IPv6 address to reach IPv6 infrastructures without requiring a connection to the IPv6 Internet.

And that’s not all that IPv6 will provide. It also eliminates the need for Network Address Translation (NAT), a form of IP masquerading developed to get around the IP address shortage by hiding entire address spaces. The primary drawback to NAT is that a host residing behind a NAT-enabled router does not have end-to-end connectivity and so cannot utilize some Internet protocols.

Network devices connected to an IPv6 network will be able to auto-configure much more robustly than is possible with the existing Dynamic Host Configuration Protocol (DHCP). You can also simply reconfigure an existing network, keeping the address suffix—and subnet—while changing the public prefix. And since an IPv6 subnet can have 264 addresses, ISPs and large institutions will no longer be forced to fragment their networks.

As with IPv4, data exchanged using IPv6 is contained inside packets. IPv6 packets consist of three elements: a fixed header with addressing information, an optional extension header that enables additional features, and a payload. IPv6 packets can be processed faster than IPv4 packets because their packet headers do not contain a checksum. Checksums are used in IPv4 to verify that data has been properly sent and received, but this task is performed at a higher layer with IPv6. In addition, some infrequently used processes have been moved out of the fixed header and into the optional header.

Countdown to IPv6

All modern operating systems are ready for the transition to IPv6, including Windows XP with Service Pack 3. For the moment, operating systems can run in a dual-stack mode, juggling the two IP standards and often two IP addresses at the same time. For example, they might use IPv6 internally and route to an IPv4 destination externally.

Operating systems also support “6to4” translation. This method allows IPv6 devices and networks to communicate across IPv4 sections of the Internet. The technique stores an IPv6 packet inside the payload of an IPv4 packet, like a ferry transports cars across a river. Relay servers or a dual-stack destination on the other side can unlock the IPv6 data once clear of the IPv4 network. As long as you have a public IPv4 address, the technique should work even if your ISP hasn’t yet adopted IPv6.

It’s harder for IPv4 devices to communicate with IPv6. Translational gateways and proxies can help but they aren’t reliable. Once your favorite Internet services switch over to IPv6-only, your IPv4-only equipment might not work. Thankfully, the dual-stack transitional phase should stave off that problem for many years.