IPv6 tutorial

IPv6 promises a stronger, faster Internet experience and lots of potential headaches for network administrators. Compiled by the SearchEnterpriseWAN.com editors, this handy IPv6 tutorial provides you with what you need to know to prepare for the IPv6 upgrade,

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featuring the expertise of SearchEnterpriseWAN.com's own IPv6 expert, Silvia Hagen.

In this guide, you will find:

What is IPv6?
IPv6 vs. IPv4
Upgrade to IPv6
IPv6 and network management
Benefits of IPv6


 What is IPv6?  Back to top ↑

IPv6 (Internet Protocol Version 6) is a set of specifications from the Internet Engineering Task Force (IETF) that's essentially an upgrade of IP Version 4 (IPv4). The basics of IPv6 are similar to those of IPv4 -- devices can use IPv6 as source and destination addresses to pass packets over a network, and tools like ping work for network testing as they do in IPv4, with some slight variations. (Whatis.com)

→ For more information read IPv6 explained


 IPv6 vs IPv4  Back to top ↑

What are the differences between IPv4 and IPv6?
IPv6 is based on IPv4 -- it is an evolution of IPv4. So many things that we find with IPv6 are familiar to us. The main differences are the following:

  • Simplified header format. IPv6 has a fixed length header, which does not include most of the options an IPv4 header can include. Even though the IPv6 header contains two 128 bit addresses (source and destination IP address) the whole header has a fixed length of 40 bytes only. This allows for faster processing. Options are dealt with in extension headers, which are only inserted after the IPv6 header if needed. So for instance if a packet needs to be fragmented, the fragmentation header is inserted after the IPv6 header. The basic set of extension headers is defined in RFC 2460.
  • Address extended to 128 bits. This allows for hierarchical structure of the address space and provides enough addresses for almost every 'grain of sand' on the earth. Important for security and new services/devices that will need multiple IP addresses and/or permanent connectivity.
  • Built in IPv6 functionality. A lot of the new IPv6 functionality is built into ICMPv6, such as: Neighbor Discovery, Auto-configuration, Multi-cast Listener Discovery, and Path MTU Discovery.
  • Enhanced security and QoS features.

Will IPv6 stop network management complications presented in IPv4?
One of the major issues in today's networks is the fact that we had to build in a lot of Network Address Translation (NAT), due to the fact that IPv4 addresses became scarce.

But NAT creates many problems because it doesn't allow for end-to-end connectivity. There are many issues to be dealt with in NAT environments, especially in the area of security, for instance with Voice over IP (VoIP). According to a study by the US Department of Commerce published in 2006, the cost for working around NAT issues ranges up to 30% of total IT expenditures.

In an IPv6 world we can save all these cost because the address space allows us to build networks without using NAT.

Is there any difference to QoS between IPv4 and IPv6?
There is essentially not much difference in the concepts of QoS for the two protocol versions. The only difference lies in the fact that the headers are slightly different, so different fields or extension headers may be used. For an example of these header differences, see RFC 2474, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers." It specifies the DS field for both versions of IP.

Basic IPv6 specification can also be used for QoS for the following fields and headers: Traffic Class, Flow Label, Routing Extension Header, Hop-by-Hop Extension Header.


 Upgrade to IPv6  Back to top ↑

What is prompting the move to IPv6?
There are a number of reasons the move to IPv6 is becoming more prevalent.
One is that IPv6 is inevitable -- there is no other solution to the address issue. Beyond this, IPv6 offers many advantages over IPv4. So the clever mind asks, "Why should I invest in expanding my IPv4 infrastructure, if I can invest in the future protocol, IPv6?"

Another point is that in Asia, IPv6 has been alive for quite some time. But the wave has also reached Europe and in the U.S., where, for instance, the Department of Defense (DoD) announced in 2003 that they will migrate their network to IPv6 by 2008 -- and that from now on, they will only buy hardware and software that supports IPv6.

So vendors who want a piece of the action need to follow suit and build equipment that supports IPv6, if they want to continue having a piece of the DoD IT budget cake. Even Google has been assigned a /32 prefix; so -- who knows? -- maybe we will google over IPv6 in the near future.

Other drivers could include mobility demands and VoIP, as well as needs for end-to-end security which requires plenty of addresses and no NAT.

The IPv6 wave is approaching; and though we can't imagine running our networks over IPv6 today, tomorrow we may wonder how we did it without IPv6.

How do you calculate ROI costs for an IPv6 implementation/migration?
To calculate ROI for IPv6 greatly depends on your network layout, your systems, your applications and services, and your strategy.

For instance, you need to determine whether you want to go for a dual-stack network or whether you plan to go straight to a pure IPv6 network. In order to get to numbers, you need to work on a migration concept which will analyze your current infrastructure, create a design for the future and then evaluate each single aspect to find out what it takes to get there.

Once those factors are determined, the time frame you have to reach your goal plays an important role, also. The sooner you start, the more digestible you can plan the single steps and the cost associated with it.

The US Department of Commerce (DoC) did an analysis, entitled Technical and Economic Assessment of IPv6, in 2006 and came to the conclusion that every dollar ($1) invested in IPv6 creates a 10 dollar ($10) return.

Will my company need to buy new equipment for the upgrade to IPV6?
In many cases, IPv6 is already part of most equipment or can be installed as a software upgrade. Type and brand of equipment, as well as age, will effect each network separately. If you have devices that you acquired recently, IPv6 should be included. In preparing for an upgrade to IPv6, one of the first tasks companies will have to do is create an inventory of their devices and software and find out to what level they support IPv6.


 IPv6 and network management  Back to top ↑

What effects will IPv6 have on managing network applications?
-- retired expert, Karl Triebes

With IPv6 there are significant changes that improve network device management. The first noticeable difference is the increase in IP addressing from 32 to 128 bits which is accompanied by an increase in the structure and allocation of addresses. The IPv6 address is comprised of a global routing prefix, a subnet ID and an Interface ID (the portion local to a link within a LAN). The global unique portion of the address space is distributed hierarchically according to the network infrastructure topology through Internet Assigned Numbers Authority (IANA). 

This allows the global routing table for IPv6 to be small, avoiding some scaling issues common with Border Gateway Protocol (BGP) routing today.

Secondly, there are enough addresses in IPv6 to give perhaps every square inch on the planet Earth a unique IP address. While this enables virtually any device you can imagine to be on the Internet, it poses a potential nightmare for an administrator to manage all the address assignments. Fortunately, IPv6 includes a feature (made of numerous smaller features) called Autoconfiguration of Nodes. This is essentially a next generation replacement of DHCP and Address Resolution Protocol (ARP) that is available in all IPv6 networks and allows you to connect a new device to the network without even minimal configuration. It also makes it much simpler to re-address your network if you change ISP's (and are thus allocated a different global routing prefix), because all you have to do is change the configuration of your router and your entire network will re-acquire new addresses with the new prefix. This is a huge reduction in the network management burden.

With the increased features of IPv6 come some potential management issues. IPv6 provides native support for security, termed IPsec. Encryption may or may not include some of the header information depending on which mode is used to form the VPN, which can reduce the amount of active traffic management that can be applied to the flows between clients and servers. Managing the security policy between the endpoints (IKE) can be tricky as well if you need to implement that yourself, but this is one of the main things an IPsec-based VPN provides. Of course, IPsec can be strong but brittle in certain remote-access situations such as accessing a corporate network from a mobile device, further adding to the management burden by an IT department trying to provide such services.

Migrating from an existing IPv4 network to an IPv6 network need not be done in one big step, thanks to new technology that provides gateway services between each, such as the BIG-IP IPv6 gateway from F5 Networks. BIG-IP provides a full proxy for traffic between IPv4 and IPv6, allowing all traffic to be translated for consumption by either IPv4 or IPv6 end points. This allows organizations to stage their migration gradually as demand for IPv6 increases.

Will IPv6 make network management an easier job?
In the long term, IPv6 will make network management easier. IPv6 has many features, especially autoconfiguration, and based on that, easier renumbering of networks. Also you have to be aware of the fact that management of IPv4 becomes more complex, as the demands on services and mobility grow constantly and they will be easier to fulfill with IPv6.

In the short term, management of IP networks means managing two protocols, IPv4 and IPv6. It is to expected that both protocols will co-exist for many years in our networks and in the Internet. However, you may try to move to an IPv6-only network as quickly as possible, in order to maintain only one protocol. But there are mechanisms in an IPv6-only environment which allow for the support of legacy IPv4 applications.


 Benefits of IPv6  Back to top ↑

What are the benefits for a company, especially ISPs, of adopting IPv6?
This question has been widely discussed in the public and there are many answers to it, depending on who you talk to.

Benefits for an ISP. In this case, I would phrase the question the other way round. In my opinion, IPv6 is inevitable. So for the ISP, it is not a question of if there are any advantages, it is simply a question of being competitive. Today there are a few ISPs offering IPv6 services. They have a unique selling point at the moment and there are customers that choose those ISPs for specifically this reason. But in the near future, for an ISP, IPv6 will not be a unique selling point anymore, it will be a minimum requirement to stay in the market.

Benefits for an enterprise. For a company, the scenario looks a little different, but only to the point in time when they should integrate IPv6. The protocol will be the Internet protocol of the coming years and it solves some issues that cannot be solved with IPv4 in a reasonable way, plus it creates the foundation for new types of services especially in the area of mobility and security. An enterprise will have to analyze their infrastructure and their extension plans to determine the right moment to introduce IPv6 rather than fixing the old IPv4 infrastructure. These plans will also depend on the network and the various requirements. The important thing is to analyze it now in order to know the right moment.

Benefits for the end user. What real benefits can IPv6 bring to end users? End users don't really care what transport protocol they use. What they want is connectivity and mobility. In the long term, only IPv6 will be able to support all the new mobile devices and services that are emerging. This is due to 1) the demand this will create for IP addresses and 2) to the advanced mobility features of IPv6. But as long as everything works, end users won't care what protocol it is.

What will be the biggest impact of IPv6?
IPv6 will be an important and major upgrade to all our networks and to the Internet. With all the transition mechanisms defined though, it will gradually grow into our networks.

There will not be a flag-day like there was with IPv4 in 1983, where the Internet was switched from NCP to TCP overnight. IPv6 can and will co-exist with IPv4 for a long time and the transition mechanisms are so flexible, that there is no specific upgrade order required.

This means, as a home user, you can use IPv6 even if your ISP does not offer it yet. And within a corporate network, you can roll out IPv6 at the edge of the network, while your backbone is still IPv4 only.

Are there any advantages from the upgrade to IPv6 for mobility and wireless?
The use of extension headers with IPv6 to carry options (that are carried in the basic IP header with IPv4) makes IPv6 much more flexible for mobile communication. Some of the extension headers are used to optimize routing in a mobile environment.

For instance, when a host wants to roam from network to network without losing its TCP connections, it will use mobile IP to do so. It then uses a home agent in its home network that will hold its TCP connections on its behalf while the mobile node is roaming. With IPv4, all communications from the mobile node will always go through its home agent regardless of which service it is connected to.

With IPv6, if the mobile node is in a remote network connecting to a service in another network, it can route packets to the service directly by using extension headers and after a few initial packets through its home agent, thereby optimizing the route. In the future, we have large numbers of mobile users roaming about using mobile IP, or Mobile IPv6 (MIPv6). The old IPv4 scenario would create a heavy bottleneck at the home agent as all traffic from all mobile nodes of its network would be routed through that home agent.

How does IPv6 benefit current and future applications?
IPv6 and its multiple features will become the foundation for new services of all different types; many which we cannot possibly imagine yet. But as the past years have shown, new types of applications appear and flood the world almost overnight. So watch out and get ready.

View our IPv6 migration guide to learn how to transition your IPv4 network to IPv6.

About the author: Silvia Hagen, CEO, Sunny Connection AG has been in the networking industry since 1990, and became a CNE and CNI in 1992. She began her career as a successful instructor, and has trained hundreds of system engineers. Today she is CEO of Sunny Connection AG in Switzerland and works as a senior consultant and analyst for many mid-size and large sized companies. Her expertise is in Directory Services and Protocol Analysis. She has developed her own courses and seminars in the area of Directory Services, Meta Directories and Protocols (TCP/IP, SLP, and IPv6.) The courses are offered through public classes or as customized trainings at customer sites.

Silvia is the author of successful books like "Novell's Guide to Troubleshooting TCP/IP" (ISBN 0-7645-4562-0), published by Wiley & Sons, "IPv6 Essentials, Second Edition" published by O'Reilly (ISBN 0-5961-0058-2) and "SLP -- Guide to Service Location Protocol," published by Podbooks (ISBN 1-893939-359). "IPv6 Essentials" has been translated to Japanese and Chinese. You can find information on all of Silvia Hagen's publications here. Through her work for the IPv6 book she has been in touch with many of the developers and early adopters of IPv6. She is also a founding member of the Swiss IPv6 Task Force and co-organized the first IPv6 Summit in Switzerland in April 2003.

This was first published in April 2009

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