Thursday, February 3, 2011

IPv6 - What you need to know


As time goes by, more and more buzz is being generated on the subject of IPv4 exhaustion and The Transition to IPv6. The problem is that many people still don't understand what this means, how they will be affected and how they should respond to this imminent situation.

I am hoping that this three part series on the subject will elucidate on the subject and give some important insight on the issues that continue to elude people. So in Part one, let's start from the beginning.

The Internet.
The Internet in its simplest form can be defined as a system of Interconnected Networks. This system was invented as a research project mainly backed by the US Military and went on to become a communications medium for geeks in a few Hi-Tech research facilities where the creators and a few learned colleagues punched away lines of commands just to read an email.

Since the technology involved communication or interaction, identification of communicating nodes or computers in this case was necessary; hence the adoption of the Internet Protocol (IP) as the preferred addressing scheme. We won't go into the details, but suffice it to say there were other competing Addressing schemes at the time, but the Internet Protocol (Fourth version) gained the most traction.

Internet Protocol (IP) Address
An Internet Protocol (IP) Address, is a unique number that identifies each host (Computer, Server, Smartphone) on a network – or shall we say the internet. For a host to be uniquely identified on the Internet it must have atleast one IP Address. “212.238.0.1” and “2001:db8:0:1234:0:567:8:1” are examples of IPv4 and IPv6 addresses respectively.

The Problem
Like I mentioned earlier, the Internet was nothing more than a research project turned communication tool. The curators of this ubiquitous technology didn't exactly envisage their creation helping a housewife find a stake recipe or even help people with bad taste in music watch Justin Bieber on Youtube – Ok, not the best example, but you get the point.

The addressing scheme (IPv4), only allowed for about 4 billion unique IP addresses and like Bill Gates' prediction on Computer Memory in 1981, Vint Cerf and his colleagues thought the 4 billion addresses as sufficient at the time – This prediction has turned inaccurate Thanks to the Dot-com Bubble in the early 2000's that put computers into ordinary households and the rich content available on the internet which is over a billion users strong. Several mechanisms have been devised in the last decade to cater for this short coming in the Version 4 of the Internet Protocol Addressing scheme. We will go over some of these shortly, but first, The impending doom of the internet...or the reports of one.

IPocalypse
There has been lots of reports on the impending doom of the internet. Some have even made allusions to an IPocalypse – (Apocalypse of the Internet Protocol). I would like to state that this is erroneous and misleading. There won't be a crash of the internet. Even after the current pool of internet resources run out, the internet will continue to exist thanks to it's design, early adopters of the newer version (6) of the Internet Protocol and the major websites that already run services on this Protocol. Websites like Google, Yahoo, Youtube, CNN and AfriNIC can now be reached on IPv6.

A common question is whether IPv6 was the most ideal solution to the problem of address exhaustion – let's take a look at some of the other remedies that have gained wide adoption and why they fall short of being a panacea to the problem of address exhaustion.

NAT
Network Address Translation or NAT allows Network Operators to allocate private addresses to End-users and requires only one or a few globally reachable address for a potentially large group of customers. Off course this means the End users have to use the gateway for traffic to the Internet. The problem with this that it:- 1) Breaks the end-to-end model of the Internet Protocol and the Internet itself. 2) Mandates that the network keeps the state of the connections 3) Makes fast rerouting difficult as traffic has to go out through the node that is facing the global internet at all times. 4) Because of its nature NAT, breaks the End-to-end security model 5) also some applications are not NAT friendly this can cause problems sometimes.

This is why NAT comes of as not a very good solution to the exhaustion problem.


CIDR
Classless Inter-Domain Routing or CIDR, employs aggregation strategies to minimize the size of the Internet’s routing table.. CIDR allows routers to group routes together in order to cut down on the quantity of routing information carried by the core routers. With CIDR, several IP networks appear to networks outside the group as a single, larger entity.

CIDR is perhaps the most widely used method but because the internet is growing constantly, It just can't keep up with the exhaustion of a finite resource.

DHCP
Dynamic Host Configuration Protocol (DHCP). Is the protocol used to assign addresses to hosts in a network automatically. DHCP is used to avoid the administrative burden of assigning static addresses to each device on a network. It also allows multiple devices to share limited address space on a network if only some of them should be online at a particular time.

The Problem is that Nodes that communicate over the internet increasingly have the need for an always-on connection state and DHCP simply doesn't offer this. This makes it a less than ideal solution.

In Part 2, we shall talk about what makes IPV6 a more ideal solution to the current problem of exhaustion, How it makes up for some of the short comings in the intermediary solutions we have discussed above and the major differences between it and Ipv4. We shall also look at how IP addresses are managed Globally.

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