IPv6 - The Next Generation Internet Protocol
Introduction
The next generation Internet Protocol (IPv6) is poised to make a new wave in the coming decade. If you wonder what the big deal is about, you need to look at some serious limitations of the current IP protocol, or IPv4 to be precise.
When the TCP/IP protocol was initially designed, they had not the faintest idea that the Internet will one day push forward the World Wide Web and support the great conflagration of people and devices literally hooked into it. The current protocol, from this perspective, has many short-comings and flaws.
One of them is the address space problem. As many of us are aware, the current 32-bit addressing used within IP is not allocated well, resulting in huge gaps of unused addresses. Also, the Internet is expanding at an exponential rate, with many more devices getting added to the network every day. Do we have a wide enough address space for them?
There are many other problems. One is the lack of security and authentication. IP does not encrypt packets. You cannot digitally sign a transmission. It is relatively easy to monitor TCP connections, even hijack them and make them yours. Hackers all over the world routinely use such tools to break into systems. Most password-requiring protocols over IP use clear text passwords. Can't you encrypt? Of course, many additional add on software can be used to get over many of these problems, but the problem itself originates in the protocol that belongs in the middle ages by today's needs and standards. Yet another problem is the lack of quality of service. If you stream an audio or video over the Web, there is no guarantee that you will have enough network bandwidth consistently to deliver the goods. In addition, the Internet today doesn't have a structure that reflects IP address allocation, thus requiring huge routing tables to be maintained by routers. Network congestion abounds. Can it deliver the goods as technology races on? This is IP version 4 (IPv4) that is in use today.
IP version 6 or IPv6 (also known as IPng - ng for new/next generation), provides 128-bit addressing (that's billions upon billions of addresses), compatibility with IPv4 addresses, security and authentication, quality of service (reserving bandwidth), plug-and-play for network device configuration, hierarchically structured routing and an ability to seamlessly integrate with the current IP during the transition stages.
An IPv6 address is represented as 8 16-bit numbers in hexadecimal, like FEDC:BA98:0:0:0:BA98:7654:3210. It is not possible to remember these. And you don't have to. The DNS service will be modified to handle both 32-bit and 128-bit addresses. Also, an IPv6 address can be dynamically built when you plug in a device, by sensing the network address from the network you are connecting to, and then using your ethernet card's address (or whatever interfaces's hardware address) to build an IPv6 address. Thus you can reconfigure automatically when moving from place to place. Your IPv6 addresses also change. Routing has been totally reworked to build hierarchies. That is, the IPv6 address itself tells the network where exactly to deliver the packets. These addresses will be portioned out to various ISPs and regulatory bodies and a huge chunk kept in reserve. This also means that your IPv6 address will change when you move to another ISP (this is currently effective due to CIDR - classless InterDomain routing - which was invented to temporarily surmount the addressing and huge routing tables problem).
Broadcasting is done away with in IPv6. Only multi-casting is present. There is also an "anycast" feature where multiple devices listen on the same address, but the packet will be sent to only one, the "nearest" device. Currently this definition can be used only by routers. This would allow, for e.g. the Microsoft Network worldwide to use the same IPv6 address for ALL its routers. Your packet will go to the NEAREST router depending on which part of the world you currently are. Combined with plug-and-play, this is ideal for mobile devices.
IPv6 datagrams can be Jumbograms (upto 4 billion bytes long)!. This is for better resource utilization in very fast networks (possibly intranets). You can "tunnel" IPv6 packets through IPv4 networks using machines that have "dual stacks" (running both IPv6 & IPv4) at the edge of the network. You can also tunnel IPv4 packets through an IPv6 network by using special addressing schemes on the IPv6 network edges. However, to make full use of IPv6 features including security and quality-of-service, currently running applications will have to be modified. The socket APIs will expand, and many of the higher level abstractions can change to accommodate IPv6 features and addressing.
Quality of service (QOS)
Quality of service (QOS) is a very important feature of IPv6. This is what has made ATM networks popular. IPv6 makes it possible to make network bandwidth reservations on traffic flows. A protocol known as RSVP (Resource Reservation Protocol) is invoked here. Essentially, all routers in the path recognize and honor flow-reservations and expedite or slow down packets as required to meet bandwidth guarantees. They can also timeout and free up resources that are unused. RSVP can be applied to multicast as well! The end result is that multimedia streaming applications may reserve network bandwidth and proceed without worrying about delivery hassles.
The Internet & the Web within the next 10-15 years would probably be something we can't even imagine today. IPv6 tries to make sure that many of the possible requirements of the future are addressed. It also has to maintain inter-operability with legacy networks like those using Novell IPX. Think of this as something like a transition from an Intel 8088 chip to a Pentium III, maintaining compatibility, but vastly enhancing the scope.
Performance-wise, IPv6 is expected to give a real boost compared to IPv4, due to efficient routing, good packet structure, Quality-of-service, the transition stage requiring that most routers upgrade over a short time to new faster technology, and of course any future technological innovations expected on the Internet.
There is a lot more to IPv6. It is still on the anvil, though sample IPv6-enabled networks and devices exist. And it is coming. So watch out for the new wave !