Google is in the process of deploying IPv6 across its internal network connecting 30.000 employees and over 70 offices across the globe with the new internet protocol. The engineers ran into a myriad of problems which can be a foreshadow of what will happen when IPv6 is rolled out across the entire internet.
IPv6 (Internet Protocol version 6) is to replace IPv4 and it is going to be the biggest architectural change to the internet since its standardization in the late ‘70’s.
IP together with TCP forms the Internet Protocol Suite (or TCP/IP) the primary protocol for moving data across the internet. TCP (Transmission Control Protocol) is tasked with the flow and sequencing of the packets. IP is responsible for delivering packets end to end, identifying the destination host by its unique IP address.
But IPv4 addresses are running out which is the main reason why IPv6 is being introduced.
The reason for the shortage lies in a decision made in 1977 by Vinton Cerf, one of the fathers of the internet. When confronted with the question: “how much address space is needed for the internet?”, he decided on 32-bit addresses. Thinking that 4.3 billion potential addresses would be enough for a project that was still in the experimental phase. Should the technology be proven they could redesign for the production version. “Of course, it is now 2011, and the experiment never exactly ended”, Cerf writes in a paper on IPv6 deployment.
Already in the early 90’s it was recognized that, considering the rapid growth of the internet, IP addresses might run out.
IANA (Internet Assigned Numbers Authority) is responsible for allocating IP addresses. It does so by distributing large chunks of address space (consisting of 16 million addresses) amongst the five Regional Internet Registries (RIRs). They in turn allocate large chunks to big players such as Internet Service Providers (ISPs), corporations and government institutions.
On February 1, 2011 IANA announced that it had allocated the last chunk of address space to the Asia Pacific RIR.
This doesn’t mean you can’t connect that laptop you hope to get for Christmas. A single public IP address can indirectly connect a private network consisting of millions of devices to the internet. For instance, IP address space in the range of 192.168.0.0 – 192.168.255.255 are designated as private and can be used over and over again in different private networks. Private IP addresses cannot directly connect to the internet but using a NAT (Network Address Translation) device such as a router the private network can access the internet using a single public IP address.
But even so with more and more people coming online each year hooking up more devices per person public IPv4 addresses eventually will run out.
Which is why IPv6 deployment is inevitable. The IPv6 address size is 128-bit increasing the address space to 340 trillion trillion trillion.
But although the v6 protocol was defined in 1998 the internet still runs by and large on v4. One of the reasons is that all internet stakeholders need to invest. Hardware and software vendors need to make their products v6 compatible, owners of large networks such as Google need to make extensive adjustments to their networks. But the biggest cost is for the ISPs who will see little return on that investment but do see a lot of risks. The distributed system that is the internet has simply never seen such a fundamental overhaul and nobody can guarantee things will go peachy.
Which is why Google’s rollout of IPv6 for its internal network makes for an interesting case study.
The Google corporate network is a good test case because it is diverse system. It runs different operating systems like Linux, Mac OS X, and Microsoft Windows on a wide range of equipment from various vendors, for connectivity different networking devices are used, it spans the globe and connects offices and corporate data centers.
One of the reasons for the engineering team to roll out v6 was that the network was running out of private IP addresses. Another was that they wanted to break the cycle in which nobody starts delivering IPv6 because nobody else does. Content providers don’t deliver IPv6 content because users have no IPv6 access, and network providers don’t migrate to IPv6 networks because there is no IPv6 content.
In the paper Deploying IPv6 in the Google Enterprise Network. Lessons learned [.pdf] Googlers Haythum Babiker, Irena Nikolova and Kiran Kumar Chittimaneni describe the challenges they faced.
As it turns out many of the networking devices and platforms come without enterprise IPv6 features. There are some that do support IPv6 but in software only which causes a severe decrease in performance.
Network monitoring tools weren’t IPv6 compatible making it difficult to analyze the performance of the v6 network during implementation.
Many applications and systems aren’t v6 compatible and can’t easily be modified. But because of their critical functions they can’t be phased out either. The engineering team ran into organizational problems too, the system administrators don’t have the time to work on compatibility problems because there is always more urgent business to attend to.
All in all the report smells of an engineer’s hell. Unexpected problems, tools that won’t work, third parties that can’t or won’t cooperate. But they wouldn’t be engineers if they let that beat them. So of course the report ends with a happy note: “There is still quite a lot of work before IPv4 can be turned off anywhere, but we are working hard towards it. The ultimate goal is to successfully support employees working on an IPv6-only network.”
To see if you’re IPv6 ready go to http://test-ipv6.com/
Via: http://www.itworld.com/networking/231929/usenix-google-deploys-ipv6-internal-network
Image: This shows the interconnections provided by Autonmous Systems (AS) between Internet eXchanges (IX).
Source: Caida.org
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About Tessel Renzenbrink
Tessel Renzenbrink holds an MA in philosophy and specialized in metaphysics. She writes about technology, energy and the changes in the cultural mindset that mark the shift towards the information age. 
