There are certainly a large number of topics that need to be studied to successfully ROUTE exam to help you better prepare for this portion of the 642-902 exam.

I hope that this article will give you some direction when studying IPv6 for the Cisco ROUTE exam. Let’s take a brief look at the main topics that you will have to be familiar with to be successful with the IPv6 material that is covered on the ROUTE exam.

IPv6 Address

The IPv6 address is a whole new beast compared to the much more familiar IPv4 address that has been used for the last 30 years; it is 128 bits, is notated in hex and just looks confusing. When studying for the ROUTE exam, it is very important to be familiar with the IPv6 address, its structure and how it can be notated; keep in mind a single IPv6 address can be notated a number of different ways using substitution and omission rules. Be familiar with all of these as questions will be asked about this specifically.

The other part of IPv6 addresses that will definitely be on the ROUTE exam is how to enable IPv6 routing and configuring IPv6 addresses (statically and dynamically). IPv6 addresses can be assigned in a number of ways including methods that are not provided with IPv4 (stateless autoconfiguration), make sure to be familiar with these for the exam.

IPv6 Address Types

If you’re familiar with IPv4, then you’re used to seeing unicast, multicast and broadcast address types. IPv6 makes use of the unicast and multicast address types in the same ways as IPv4; it does however differ in that it does not support broadcasts. The duties that have traditionally used the broadcast address type in IPv4 have been substituted either by directed unicast or the new Anycast address type. The Anycast address type is used to locate and use the closest device utilizing the anycast address.

Inside these three main address type categories there are also sub-types that a candidate must be familiar with including: Global Unicast Addresses, Link-Local Addresses, and Site-Local Addresses.

IPv6 Routing Protocols

Just as a candidate must be familiar with IPv4 routing protocols they must also be familiar with IPv6 routing protocols. Most of the concepts that have been learned for these protocol implementations using IPv4 are the same so learning the additional requirements for an IPv6 implementation should not be that much of a stretch. Make sure to reserve some amount of time to configure these concepts in a lab environment (or dynamips).

IPv4/IPv6 Address Transition

Part of a wider scale implementation of IPv6 is transitioning IPv4 networks to IPv6 and providing a communications method between IPv4 and IPv6 devices. There are a number of different methods that can be used to provide this capability; many of these are covered in the ROUTE exam. The following topics are covered on the exam; ensure a familiarity with the concepts and application (configuration) of these concepts.

• Dual Stack
• Manual IPv6 Tunnels
• GRE Tunnels
• 6to4 Tunnels
• IPv4 Compatible Tunnels
• ISATAP Tunnels
• NAT-PT

Summary

Hopefully, the content in this article will help you get a good direction when studying for the IPv6 portion of the Cisco ROUTE exam. Keep in mind that while there is a lot of material covered on this exam, it is an achievable task and can be completed successfully.

This year has already had some interesting developments with the usage and adoption of IPv6 into the mainstream, not only in Asia and Europe, but surprising updates in the United States as well. Let’s take a look at some of the latest UPv6 implementations and news.

Sprint IPv6 Deployment

Sprint, one of the largest Internet providers across the globe has just completed the first phase of its IPv6 deployment for larger businesses and wholesale partners utilizing its North America Internet backbone.

Sprint plans to continue its implementation of IPv6 over the next few months and by the end of the year, begin rolling out IPv6 support to its remaining domestic points of presence and then start the process of deploying IPv6 to its Europe and Asia backbones.

This development is a major step forward for commercial adoption of IPv6 and I believe will begin a domino effect across the ISP community to deploy and offer IPv6 services. Large providers have limited deployments now, but once a stronger demand for IPv6 grows, larger scale deployments to backbones for commercial use will follow.

Facebook and IPv6

Adoption of IPv6 has now spread to the social networking world. Facebook recently announced at the Google IPv6 Implementers Conference that it was deploying IPv6 to be used with its social networking site.

Facebook stated that its foray into the IPv6 world was “experimental”, but it shows a trend for sites requiring worldwide connectivity. Users across the globe are already using IPv6 and providing a direct access to those users can increase their customer base.

In Facebook’s world of free social networking, advertisements are the real money makers and providing a larger and more global audience can only bring smiles to hungry vendors that advertise their goods and services there.

As sites like Facebook adopt IPv6, other sites like that offer similar services, including online computer games, will slowly but surely follow suit. Internet marketers are also starting to see the larger global reach that IPv6 will bring, but it will take more ISPs offering IPv6 services especially in North America for them to invest and take advantage.

US Federal Government Requires Vendor IPv6 Conformance

The United Stated Federal Government has put into effect a mandate requiring all IT equipment purchased in 2008 or later supports IPv6. As of July 1, 2010, the Federal Government has taken another step farther in enforcing this compliance.

As directed by the Office of Management and Budget (OMB), the Federal Acquisition Regulation (FAR), which is the primary acquisition regulation for the Federal Government, was modified. The modification included a requirement that all IT equipment must be evaluated and certified by an accredited laboratory for IPv6 conformance in accordance to guidelines set forth by the National Institute for Standards and Measures (NIST) and the USGv6 Group.

The step taken by the OMB is a major one. Changing provisions in the FAR to identify key parameters of IT equipment purchases is not a small undertaking. It is now up to the Federal Agencies themselves to implement IPv6 on the equipment that they have purchased. Groups like the Department of Defense and Department of Energy have already deployed IPv6 for some of their networks and some are working on their own rollouts, but there is more work to be done.

IPv6 Education

IPv6 adoption is continuing to rise, slowly but surely. Understanding of IPv6 in the coming years will become a very important skill for IT professionals and those with transition experience will definitely be in high demand.

The CCNA 604-802 exam requires candidates to have a good understanding of IPv6 and how to implement the protocol.

In my previous article, IPv6 Addresses: Form and Function, we compared the structures of the IPv4 and IPv6 addresses and headers. We also examined the differences in the types of IPv4 and IPv6 addresses.

In this article, we will take the next step and investigate what types of implementations are possible for IPv6 and how to assign an address to interface. Upcoming articles in this series will focus on some of the key features like mobility and IPSec and also look at configuring routing protocols to use IPv6.

IPv6 Implementation Strategies

There are four distinct methods to implement IPv6 in a network infrastructure:

• Native Implementation
• Dual Stack Implementation
• IPv6 Tunneling
• IPv6 Only to IPv4 Only Translation

Let’s go over each of these in more detail.

  •   IPv6 Native Implementation

The first implementation method is to install IPv6 in a native configuration. This configuration configures all hosts and routers to utilize IPv6 only and not in conjunction with IPv4.

Native implementation limits the network to only IPv6 communication to other networks and would require translation to interface other IPv4 networks.

  •   IPv6 Dual Stack Implementation

The second and most popular implementation is dual stack. Dual stack implementation allows IPv4 and IPv6 addresses to exist on the same physical and/or logical interface. This implementation is also the easiest to implement in an environment that already is established.

The primary concerns for the dual stack implementation are in software and hardware. Hardware must be evaluated in the network infrastructure to see if there is proper memory for route tables and the switch forwarding tables to handle IPv6 routes and packets. Software on the network infrastructure must support IPv6 configuration and routing protocols, while operating systems on the host side must also be IPv6 capable.

Dual stack offers the best of both worlds with hosts able to communicate with other hosts on networks that could support either protocol. Let’s take a look at what IPv4 only application stack looks like for data flow as depicted in Figure 1.

So how would a dual stack implementation work? Well, Figure 2 shows how an application must be aware of both IP stacks to utilize either. Operating systems are configured to select which one will have priority if connectivity is available on the remote side for both protocols. If applications allow, like web browsers, IPv4 or IPv6 addresses can be manually selected.

  •   IPv6 Tunneling

The next implementation available for IPv6 is tunneling. Tunneling is used to connect two native IPv6 implementations over an existing IPv4 only network, which is typically seen as a WAN network.

Edge routers for each IPv6 implementation are connected to the IPv4 network and a tunnel is configured between them. IPv6 original headers and payloads are not modified in the tunnel, but instead an IPv4 header is inserted in front of the IPv6 header for transmission over the IPv4 network and then stripped off on the other side.

Figure 3 displays the implementation of this tunnel and communication between two IPv6 native environments.

One of the most common tunnel protocols to use for this implementation is 6to4 and is defined in RFC 3056: Connection for IPv6 Domains via IPv4 Clouds. The 6to4 protocol supports a dynamic method to tunnel IPv6 addresses across IPv4 clouds and will utilize global unicast IPv6 prefixes for each IPv6 site for communication. 6to4 must be installed on the edge routers and will map addresses according to their global prefixes, so IPv6 route propagation to other sites is not needed.

  •   IPv6 Only to IPv4 Only Translation

IPv6 only to IPv4 only translation is the last implementation method we will examine. Why would we need this? Well, IPv6 nodes may require interaction with IPv4 only nodes for certain services such as: mail or web services.

There are several ways to accomplish translation. The most commonly method used is Application Level Gateways (ALG), which utilizes a server that act as proxy to services that may be other IPv6 or IPv4 nodes. Figure 4 shows how this might be implemented.

For ALGs to properly function the applications on the server must be IPv6 aware and the server must configured to support both protocols. The best location for the ALG is often identified by the location of the targeted services. For IPv6 nodes that require access, but offer no services to other IPv4 nodes, placing an ALG at the edge of the IPv6 network is the best location.

Let’s look quickly at some other translation methods that could be employed. Other translation methods include NAT-PT, TCP-UDP relay, Bump in the Stack (BIS), Dual Stack Translation Mechanism (DSTM), and SOCKS-based IPV6/IPv4 gateway.

• NAT is not favored for use with IPv6, but it does offer a mechanism to achieve connectivity to end IPv4 nodes.
• TCP-UDP relay is similar to NAT-PT, but performs translation at the Transport Layer of the OSI stack and not the Network Layer.
• BIS is designed to work with dual stack hosts and was used as an initial step for translation since many applications did not support IPv6.
• DSTM allows dual stacked hosts in IPv6 only domains to communicate to other IPv4 hosts by dynamically creating tunnels for communication.
• SOCKS-based IPv6/IPv4 gateway is based on the SOCKSv5 protocol and is a proxy mechanism to translate addresses.

Translation between IPv6 and IPv4 is an advanced topic that requires more in depth study beyond the current CCNA scope and is taken up in more detail for CCNP candidates.

Implementing IPv6 Addresses on Cisco Router Interfaces

Now that we have talked about IPv6 implementation schemes, let’s look at how to implement IPv6 addresses on a router interface. Before this can be accomplished, you need to verify that the current version of IOS code on the Cisco router will support IPv6.

Once you have logged into a router and entered enabled mode, type "show ipv6 ?" at the router prompt. If a syntax error occurs, the IOS version is not setup to support IPv6 and will need to be upgraded.

To enable IPv6 on a router for configuration, IPv6 unicast routing and CEF forwarding will need to be enabled. Enter configuration mode on the router and type the following:

Router (config) #ipv6 unicast-routing
Router (config) #ipv6 cef distributed

This will enable IPv6 to be statically configured for routes and on interfaces. Now let’s configure and interface with IPv6 address.

Below is an example of a ten Gigabit Ethernet interface 2/1 that has a sub interface assigned. The designation of the interface is ten 2/1.1. IP address currently assigned to the interface is 192.168.100.1/30. A show interface gives us this result:

Router# show interface ten 2/1.1
TenGigabitEthernet2/1.1 is up, line protocol is up (connected)
Hardware is C6k 10000Mb 802.3, address is 001c.b0b4.7400 (bia 001c.b0b4.7400)
Description: “Interface 1″
Internet address is 192.168.100.1/30
MTU 9216 bytes, BW 10000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 501.
ARP type: ARPA, ARP Timeout 04:00:00routert#sh int ten 2/1

Now let’s enter configuration mode again and add ipv6 address.

Router (config) #interface ten 2/1.1
Router (config-subif) #ipv6 address FEC0:0:0:100::1/128

We have now configured the interface with an IPv6 IP address, but to see the result and all the associated IPv6 types of addresses that were discussed in my previous article, a special show command is needed for the interface. The example below displays the IPv6 addresses assigned to the ten 2/1.1 interface:

Router# show ipv6 interface ten 2/1.1
TenGigabitEthernet2/1.1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::21C:B0FF:FEB4:7400
Description: “Interface 1″
Global unicast address(es):
FEC0:0:0:100::1, subnet is FEC0:0:0:100::1/128
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF00:1
FF02::1:FFB4:7400
MTU is 9216 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 0 milliseconds
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
Hosts use stateless autoconfig for addresses

You can clearly see that interface has a link-local and a global unicast address. Also, the Joined group addresses define the multicast and anycast addresses also needed for our router interface using IPv6.

What Did We Learn?

In this article we looked at the various methods for implementing the IPv6 protocol and talked about how to configure a Cisco router interface to use IPv6.

Understanding the implementations is an element for CCNA candidates to be aware of and so is IPv6 address assignment to router interfaces. These topics are basic building blocks overall IPv6 design and configuration and future articles will drill down into more features and configuration.

IPv6 has some real complexity, but proper training and education can empower you with the tools to take full advantage of this protocol.

As CCNA candidates, a solid understanding of the IPv6 protocol and how to use it in addition to IPv4 is essential. In my previous article, we examined the history of IPv6 and answered the question of Why is IPv6 needed?

In this article, we will examine the structural differences between IPv4 and IPv6 and we’ll investigate the different types of IPv6 addresses and how they communicate.

IPv4 vs. IPv6: Structure Comparison

In my last IPv6 article, I mentioned that IPv4 addresses are 32 bits in length and IPv6 addresses are 128. The 32 bit structure of the address for IPv4 was designed to be represented as four separate octets, or sets of eight bits, separated by dots. The maximum range of values in each octet is seen to be 0-255.

IPv6 addresses contain eight different fields, instead of octets, and each field consists of 16 bits. Due to their larger size, IPv6 addresses are noted using hexadecimal characters, not decimal as seen with IPv4. I would strongly advise reviewing hexadecimal notation (0-15 = 0-F) before doing anything with IPv6 (and for your CCNA exam), just as you would have reviewed binary notation for IPv4.

Another important item to note about IPv6 addressing is the subnet mask identification. IPv4 could use the standard 255.x.x.x or the /xx CIDR of VLSM notation. IPv6 only uses the /xx notation for mask representation.

The example in Figure 1 illustrates some of the structural differences you would see between IPv4 and IPv6 address.

IPv6 addresses can also be compressed in size if certain conditions exist. If a field contains all zeroes, that field can be reduced to just one zero. In addition, if there are multiple fields adjacent to one another that have all zeroes, those fields can be displayed by on a “::” notation.

It definitely can get confusing if you have multiple fields missing from the address, but there is an important point to remember. The compression to the “::” notation can only happen once in an address. You would be allowed to have a “::” and a few single 0 fields, but anything else is invalid.

Figure 2 below shows two IPv6 addresses and the valid and invalid ways to compress them.

Continuing with our comparison on structure, let’s dig deeper and look at the full IP address headers of IPv4 and IPv6. To best understand the header configurations, you may want to look up the corresponding Request for Comments (RFCs) that are posted by the IETF for topics that they wish to become standardized.

RFC 791: Internet Protocol DARPA Internet Program Specification, defines the IPv4 header and description of the IP packet, while RFC 2460: Internet Protocol, Version 6(IPv6) Specification, describes the same for IPv6.

Some of the IETFs RFCs are lengthy, often contain high level research discussion points, and can read like very bad stereo instructions, but careful reading can unlock a lot of useful information.

The IP packet contains the IP header and a data payload. For IPv4, the IP header is a total of 20 bytes (160 bits), but this can be increased if the options field is used. The options field is variable in length and if a field does not equal an even 32 bits, padding is added to accommodate. A graphic of the IPv4 header is shown in Figure 3.

 

Figure 3: IPv4 Header (click on image to expand)

 

In contrast, IPv6 addresses utilize a fixed length of 40 octets (320 bits) and have been simplified in its format compared to the IPv4 version. The IPv4 options field has been replaced by extension headers, which were designed to provide more structure and easier processing for network devices.

IPv6 addresses can contain zero, one, or multiple extension headers depending on the services the IP packet will be supporting. As you can from the structure of the IPv6 header graphic in Figure 4, a Next Header field identifies any headers that follow and this field is present in all extension headers, thus providing a defined chain.

 

Figure 4: IPv6 Header (click on image to expand)

 

Types of IPv6 Addresses

Different types of IPv6 addresses are defined in RFC 2373: IP Version 6 Addressing Architecture. As we look at these address types, it is important to understand that unlike IPv4, IPv6 does not use Broadcasts in its communication and therefore, does not require network number and Broadcast addresses for each subnet.

Much of the functions like ARP (Address Resolution Protocol) and other subnet only protocols are accomplished with different mechanisms that utilize Multicast or Anycast instead of Broadcast.

Unlike IPv4, each host and router utilizing IPv6 will have multiple IPv6 addresses which are used for different functions. The address types seen with IPv6 are:

• Link-Local
• Global Unicast
• Loopback
• Multicast
• Anycast

IPv6 did contain a private address space called a Site-Local address, but this was removed from the IPv6 RFCs in 2004. The following tables describe the required addresses and their representation for hosts and routers.

Putting the IPv6 Address Together

We have talked about the representation of the IPv6 address compared to IPv6 and listed the different types of IPv6 addresses. Now let’s dig deeper into the formation of an IPv6 addresses.

To illustrate this topic, I will use the Link-Local and Global Unicast addresses as examples.

Link-Local addresses are used for communication between nodes on the same local link or subnet. Communication to the broader Internet requires the Global Unicast address. In IPv4 and IPv6, addresses can be subnetted down to very small groups, but the IETF has chosen that IPv6 addresses utilized in the broader Internet will use a 64 bit interface identifier or host id. This consumes the last half of the 128 bits of the IPv6 address.

This same interface identifier is utilized for both the Link-Local and Global Unicast addresses on a network interface. The interface identifier can be configured manually or automatically utilizing the EUI-64 address. This address is a combination of a 24 bit manufacturer id provided by the IEEE and a 40 bit value given to the product by the manufacturer.

Why consume so much of the address for host id you ask?

The IETF structured the first block of 48 bits of the IPv6 address to utilize a very hierarchical structure for routing in the Internet and this block is often referred to as an IPv6 Global Prefix. The minimum subnet that can be assigned from a Regional Internet Registry (RIR) is /48. This leaves 16 bits of the first block of 64 bits of an IPv6 addresses to be used by a site or ISP for subnetting.

Based on this format, the IETF believes that there will be enough addresses to support the world’s IP addressing needs for decades to come. An illustrated example of the structure of a Link-Local and a Global Uncast Address is shown in Figure 5.

What Did We Learn?

In this article, we investigated the differences between IPv4 and IPv6 addresses and reviewed the different ways to display an IPv6 address. In addition, we discuss some of the types of IPv6 addresses and what the format means.

As you can see, there is a bit more complexity to IPv6 than IPv4, but also a great deal more structure and flexibility.

In upcoming articles, I will explain some of the key features of IPv6 such as: stateless and stateful configuration, end-to-end encryption, and IP MTU discovery. I will also address how to implement this new protocol into your network and discuss what is needed for configuring IPv6 to use different routing protocols.

IPv6 has a lot of promise, but new protocols like this often require a great deal of change in a network to properly implement and significant change is often feared. As we look at all the necessary requirements for implementation of IPv6, we will find that some of the fears we might have can be easily alleviated.

But before you begin to study the formats and functionality of IPv6 for your CCNA exam, you should have a firm grasp of why this new protocol is needed and its role in the future of networking.

In this article, we will walk the history of this protocol, investigate some of the issues driving IPv6 to the forefront, and finally look at who is using IPv6 today and what can be expected in the future.

A Brief History of IPv6

As early as 1990, experts began to predict the current IPv4 address space with its current rate of growth would soon run out.

The unicast available IP Classes at the time were A, B, and C. In 1992, Classless Internet Domain Routing, or CIDR, was introduced to summarize IPv4 blocks more efficiently and slow the exponential growth pattern of the global Internet routing table.

Later in 1993, the Internet Engineering Task Force (IETF) recognized the need for a new protocol to address many of the current IPv4 shortcomings and started a working group designated IP Next Generation (IPng) to organize its development.

In 1994, many of the Internet standards committees approved this new protocol and it was assigned version number 6.

As part of early deployments, IPv6 test beds were created to generate exposure to the new protocol starting with the first IPv6 backbone, 6bone, which was created in 1996. The first IPv6 exchange point, 6TAP, was developed one year later at the Chicago STARTAP exchange point.

In 1999, the regional Internet registries (RIRs), the organizations responsible for assigning IP address space, began assigning the first block of global IPv6 prefixes for widespread use. As early as 1996 operating system providers were developing specialized patches to support the new protocol, but most mainline releases were not available with some basic IPv6 capability until 1999.

In 2001, the IPng working group officially changed its name to IPv6.

A Look at the IPv6 Issues

Now that we’re aware of the brief history of this new protocol, let us look more in depth at some of the reasons for why it was needed.

In this article, we will focus on three of the primary issues:

• IPv4 address exhaustion,
• growth of the global Internet routing table,
• and the disparity in regional allocation of addresses.

IPv4 Address Exhaustion

As I mentioned before, the IPv4s address space was seen to be limited and with the development of the World Wide Web, exhaustion of those addresses became more and more apparent.

To illustrate this issue, let us look at the current IP address allocation (Figure 1) computed from data recorded for the Internet Assigned Numbers Authority (IANA) as of January 2010. The IANA is the organization responsible for coordinating the DNS root domain, allocating IP addresses to the RIRs, and managing various Internet protocol number assignments.

As you can see from the chart, the unassigned portion of the IPv4 space is now only 10% and other addresses are either private or are not usable as they have been designated for multicast or still slotted for testing or further use (Class D and E addresses).

In 2002, this unassigned portion of addresses was at 28%. Various experts on IP allocation and address exhaustion continue to debate the timeframe when the addressing space will run out. Dates vary from late 2011 to early 2015, but the majority of them believe that 2013 is the most likely target.

The IPv4 address structure is comprised of 32 bits for a total of 232 or 4,294,967,296 addresses. With all the subtractions for network numbers, broadcast addresses, and private or unusable address blocks, the number of usable addresses is much less. IPv6 has a 128 bit structure which supports a total of 2128 or 3.4 x1038 addresses, seemingly enough to provide addresses for the next few decades.

A colleague of mine, who has served on IETF working groups, once told me, “There are enough IPv6 addresses for every blade of grass on the planet.” I believe he might be right.

The Growth of the Global Internet Routing Table

Another issue that has promoted the need for a new IP layer protocol is the rapid growth of the global Internet routing table.

Ever since 1992, the Internet routing table has been on an exponential growth curve. CIDR with its route summarization and the addition of route aggregates have slowed the growth, but the table today does not have a well defined hierarchy and as the size continues to grow, efficient routing will become more difficult.

IPv6 was designed to have a much more hierarchical structure to support aggregate routes for more efficient and scalable routing. To provide a better understanding of the growth issue, Figure 2 shows the growth pattern of the routing table over the past two decades.

Figure 2: Global Internet Routing Table Growth from www.cidr-report.org.

The Disparity in Regional Allocation of Addresses

The last issue we will cover today is the regional assignment of the current IPv4 address space. As I mentioned before, the five RIRs are responsible for assigning IP addresses. Each RIR covers a specific region as shown below:

1. ARIN – North America and parts of the Caribbean and North Atlantic Islands
2. AfriNIC – Africa and parts of the Indian Ocean
3. APNIC – Portions of Asia and the Pacific Ocean
4. LACNIC – Latin American and part of the Caribbean
5. RIPE NCC – Europe, the Middle East, and central Asia

Due to the fast growth of the Internet in the North American region, nearly 75% of the IPv4 address space has been allocated in that region. Many countries like India, China, and other densely populated areas were left with minimal allocations.

In response to this issue, the IPv6 protocol was designed with a Global Prefix structure that includes plenty of addresses to support balanced allocations across the world.

Who is Using IPv6 Today and What Might We Expect?

Today, IPv6 is deployed in various countries around the world. IPv6 can be deployed as a native IP protocol or “dual-stacked” with IPv4 running on the same interfaces.

China has deployed two of the world’s largest native IPv6 networks and over 50% of South Korean homes utilize broadband connections with IPv6. Japan has developed a nationwide dual-stacked network and European countries are rolling out IPv6 for commercial and government use.

In the United States, the use of this protocol has not been as pronounced. Much of the commercial world has not embraced the need at this time due to the availability of IPv4 addresses in the region. However, the United States Government Office of Management and Budget issued a directive requiring all federal agencies to be IPv6 compliant by June 30, 2008.

IPv6 was not intended to be running on all agencies networks, but all hardware and software must support the new protocol and plans must be in place for a smooth transition to a dual-stacked or native implementation.

This implementation plan and the ever approaching exhaustion of IPv4 addresses will eventually move the North American commercial world to utilize IPv6 mainstream, but only time will tell.

However, no one expects this to be a quick transition. IPv4 support will likely be necessary for years or decades to come.

Luckily, Windows Server 2008 comes equipped with standard features to help with the move to a new network protocol.

Allowing for interoperability between IPv4 and IPv6 networks is not a trivial process. Fortunately, the designers of IPv6 have already come up with most of the framework to handle the interplay.

At the top of the list is Intra-Site Automatic Tunnel Addressing Protocol or ISATAP (ah, more acronyms).

With ISATAP, when a network in your site that is running IPv6 needs to talk to a network running IPv4, a properly enabled router will encapsulate the IPv6 packets inside of IPv4 packets and in the reverse, add IPv6 headers to incoming IPv4 packets.

The best part is that there is nothing for the workstations or servers to do. For all they know, they are talking to the same kind of network.

What if your organization is all about IPv6, but they have to communicate over a non-IPv6 network like the Internet?

Another technology known as 6to4 automatically creates tunneling between the networks by temporarily packaging the IPv6 packets inside IPv4 packets and then returning them to their original state when they arrive at their destination.

What about an application that uses IPv6?

For that, Microsoft utilizes Teredo. In Windows Server 2003, Teredo wouldn’t work with domain member computers. Not any more. Now, Teredo is supported on domain member computers and domain controllers so there will be no seams in the IPv4 and IPv6 networks from an application standpoint.

What Do I Have to Do?

So far, there isn’t any work for the average systems administrator here. "Hey, what are we waiting for?"

Well, besides the network guys freaking out (this will be tougher on their end), there are a some Windows Server functions you’ll have to get right first.

One of them is DHCP. Right now, all of your DHCP servers are configured with IPv4 scopes and happily doling out those addresses to all comers. Windows Server 2008 supports DHCPv6 which is, of course, DHCP using IPv6 addresses.

Although a Server 2008 DHCP server can send out both kinds of addresses, there is still no way to “translate” how an IP address is assigned, so you’ll have to re-create your scopes to get the right IPv6 addresses out there to the right systems.

The tough part will be making sure that systems you want getting IPv6 addresses get IPv6 addresses and the others get the IPv4 addresses.

DNS is another tricky spot. IPv6 addresses will be AAAA (quad-A) records in your tables. Obviously, your IPv4 DNS servers won’t have any idea what those are.

Also, since there is no way the average non-photographic memory systems administrator will be able to memorize IPv6 addresses of more than a couple of severs (if any), name resolution is going to have to be more robust than ever.

To this end, all domain controllers will host DNS which will complicate your efforts to define who contacts which DNS process.

The good news is that configuring these services will be pretty much the same as it is now, only the input field will take IPv6 addresses instead of the four blanks separated by periods (and since IPv6 address can be abbreviated, there will be no more automatic cursor movement to the next field, so the backspace key will actually work if you fat finger part of the address instead of stubbornly refusing to move back to the previous dotted section).

For example, manually configuring an IP address takes place in the same way, on the same screen. You’ll put in the default address and default gateway in the same fields. The only difference is that you will be typing a lot more.

Benefits of IPv6

There is more in the move to IPv6 for you than just saving the Internet (a noble goal in and of itself).

The IPv6 standard allows for TCP to be offloaded down one level. So, your new network cards will handle TCP at the hardware level, and your old ones will still benefit from processing occurring in the miniport.

This means less work for your servers and more power for your users.

Another huge benefit is that you will finally be able to get rid of WINS!

A newer more robust service that works tightly with DNS called GlobalNames Zone will handle all the simple name (non-fully qualified) resolution for your network. In fact, this may be where you want to get started with your migration.

The biggest time saver will be the ability to make network configuration changes on the fly without a reboot.

IPv6′s stack allows for the ability to retain configuration settings so those late workdays where you have to stay just to make sure a reboot goes through are over (at least for IP configuration changes).

Thanks to the translation protocols provided at the router level and the fact that all Windows Server 2008 systems will have fully integrated IPv4 and IPv6 stacks means that the migration to IPv6 will be as painless as possible.

Of course, there is no way it will be pain free. Then again, if it was easy, everyone would do it, and you would get paid a lot less.

A long time ago, in a galaxy not so far away, there was the Internet.

The Internet was a network that allowed information to be shared between computers regardless of their location. It was pretty cool.

Of course, you had to know Unix in order to do anything useful, and getting a file meant using the command-line FTP command (and hopefully remembering to set your type to binary when necessary).

Frankly, there were only a few people capable of doing such things, but nevertheless, the designers of this revolutionary Internet-thingy built an addressing scheme with TONS of room for computers to be added.

They called it IPv4.

Bill Gates once famously said that 64K was more memory than anyone would ever need. It’s hilarious today considering you can’t even run Notepad in 64K and Windows Server 2008 requires a minimum of 1GB of RAM.

Still, it can be hard to see the demands of the future. A similar fate befell those intrepid pioneers of the Internet, who in a slightly wiser move, created a way to address computers using the now very familiar dotted notation.

Theoretically, the IPv4 specification could support up to 4.2 billion different machines. Considering that less than 10,000 computers were connected to the Internet in 1995, this probably seemed like plenty of space. Times change.

Having just one computer used to be a big deal for the average family. Now, most people in America have at least one, and plenty of people have two, three, or more. Not to mention, all the other countries and their multitudes of users. And, that doesn’t even include the vast number of servers out there, plus all those newer must-have gadgets that need a way to connect to the Internet.

In the end, like Bill Gate’s 64K of memory, the IPv4 address space has proved to be too small.

Welcome to IPv6

None of this is a surprise to the engineers that help set the standards for the Internet. However, considering that IPv4 has been widely adopted across virtually every company, product line, hardware vendor, and country in the world, changing the standard is not small matter, and certainly not something anyone wants to have to do again in this lifetime.

Which brings us to the IPv6 standard and Windows Server 2008.

None of this is a surprise to you either. As a competent systems administrator, you know all about IP addressing and the difficulties involved in getting fixed IP addresses for your external facing servers.

You’ve seen the forms and the ridiculous third-degree you get from your ISP when you want another address. You know that IPv6 actually came on Windows Server 2003, but chances are you haven’t implemented it yet. After all, it didn’t really seem all that necessary and why make extra work for your team?

With Windows Server 2008, things are different. For starters, unlike in Server 2003, in Server 2008, IPv6 comes installed and enabled by default.

In Server 2003, IPv6 was a separate protocol. In Server 2008, IPv6 is part of the standard TCP/IP stack in compliance with current standards. (In order to help with the transition to IPv6, IP stacks handle both IPv4 and IPv6 packets.) So, you couldn’t even uninstall IPv6 if you wanted to. Not that you would want to because the stack will work perfectly fine with either IPv4 or IPv6.

Actually, as Microsoft prepares for the future, many of its core server features are already starting to support IPv6 and using them on your current IPv4 network actually involves backwards compatibility mechanisms instead of the other way with Server 2003 using compatibility mechanisms to handle IPv6.

You’ve probably read elsewhere about IPv6, but here is a quick refresher.

• IPv6 addresses are 128 bits written as eight sets of four 16-bit hex digits
• Looks like this: 2001:db8:bc92:0000:0000:1293:91c2:0012
• The IPv6 header is always exactly 40 bits.
• This is huge for that overburdened network hardware that spends a lot of computing power detecting where the IPv4 header ends.
• IPv6 supports up to 3.4 x 1038 addresses and the addresses will be hierarchical, meaning that the start of an address will give some indication of its location.

See Your Introduction to IPv6 for a more detailed overview.

IPv6 in Windows Server 2008

So, how exactly does IPv6 figure into a Windows Server 2008 environment?

For starters, the days of memorizing IP addresses is pretty much over. Right now, one of your goto moves in troubleshooting is to try and connect via IP address. You’ll need a list if you want to do that in IPv6, so you need to make sure your name resolution is rock solid. Which brings us to WINS.

Since the days when Microsoft was only fit for tiny networks, WINS has been around as a way to resolve simple names on small networks. Though WINS was better than the old computer browser, it was still a bit of a kludge on an otherwise solid platform. That dinosaur is finally going away, replaced by the GlobalName Zone or GNZ.

The good news is that most of your same tricks for IPv4 will work seamlessly with IPv6.

Need to PING a computer? No problem. Same command, same results, actually, better results. To PING by address, no change is needed. To PING by name, you’ll need to throw in the ipv6 switch. But, you also get additional switches enabled by the new header including the ability to do a round-trip traceroute to see not only how the traffic gets there, but also how it gets back.

Of course, any transition this big won’t be a no-brainer. In order to use IPv6, your routers will have to support it. If they aren’t ancient, this won’t be too much of a problem since the router companies have been building in IPv6 longer than anyone else.

Also, your firewalls and intrusion detection systems will need to support the new protocol. This is where things get interesting.

Because of the new header, the entire protocol stack can be filtered against, so you can get even more granular with your rules and block out some of the current tricks. You’ll also have to get a pool of IPv6 addresses and configure your DNS and DHCP servers to handle those.

Fortunately, the designers of IPv6 included several migration standards as well, all fully supported in Server 2008.

For example, a tunneling protocol allows for IPv6 packets to be encapsulated inside IPv4 packets so that when they hit an IPv4 network, they sail along as planned.

In short, there is a lot of work ahead, but it seems that Windows Server 2008 will be fully up to the task. That is, whenever you are.

Living in a world where nearly every household has more than one computer, imagine the number of IP addresses required for them. Likewise, more and more IP telephones and IP television sets are being introduced around the world, ensuring that the public IP address range will eventually be exhausted. The Network Address Translator (NAT) has been implemented to provide a temporary solution to the scarce number of IP addresses.

Under these circumstances, the answer is: “YES” we definitely need a new, evolved, IP version; one that is more flexible, scalable, and adaptable to the growth and changes of the Internet. This new version of IP is IPv6 and extensive details on this can be found in IETF RFCs 2460 through 2466.

So what can we expect from the new IP version? Here’s what IPv6 has to offer:

• Billions of addresses with no possibility of exhaustion
• Ability to lighten the burden of huge routing tables
• Provide extra security features
• Simplify the routing process
• Allow efficient and accurate Quality of Service options
• Support possible future evolution
• Provide interoperability between old and new version

Main Features and Improvements in IPv6

• Simpler Header Format – IPv6 contains only eight fields, compared to fourteen fields in IPv4, making its processing faster and consequently improving throughput.
• Longer Address Space – Source and destination addresses are sixteen bytes long each, versus four bytes in IPv4, which eliminates the shortage on IP addressing space.
• Hierarchical Addressing Scheme – IPv6 provides a more efficient addressing scheme which decreases the huge number of routing entries in backbone routers with its efficient summarization capability.
• Built-in Security – Data integrity and authentication are assured in IPv6 with the use of IPSec.
• Better QoS support – A completely new 20-bit field in the IPv6 header is used to identify different traffic flows between a source and destination, and apply the necessary policies appropriately.
• Extensibility – At the end of the IPv6 header, various extended options can be supported, making it possible for extensions to be easily adaptable.

IPv4 and IPv6 Header Comparison

IPv4 Header

IPv6 Header

After taking a closer look at the diagrams of headers for IPv4 and IPv6, here’s a rundown of the main differences:

• IPv6 header consists of 40 octets in contrast to the 20 octets in IPv4.
• Seven fields in IPv4 (marked with light blue shading) are not used in IPv6.
• Three field names (marked in light green shading) are kept the same from IPv4 to IPv6.
• Four fields (marked in light yellow) have changed names and position from IPv4 to IPv6.
• One completely new field is incorporated in IPv6 (Flow label field).

IPv6 Header Details Include:

• Version – A 4-bit field that is always 4 in IPv4 and 6 in IPv6.
• Traffic class – This field is similar to the ToS field in IPv4 and it is used for Differentiated services classification.
• Flow label – This is a new 20-bit field that is designed for differentiating traffic flows.
• Payload length – Similar to Total Length field in IPv4, shows how many bytes follow the 40-byte header of IPv6.
• Next Header – Identifies the upper layer protocol, similar to the Protocol field in IPv4.
• Hop Limit – The concept of this field is similar to the TTL field in IPv4, which is to indicate the maximum number of hops a packet can traverse before being dropped.
• Source address – 16-bytes address identifying the source address of the packet.
• Destination address – 16-bytes address identifying the destination address of the packet.
• Extension headers – These are optional headers that can be used to provide extra information.

All About IPv6 Addresses

IPv6 addresses are written in eight groups of four hexadecimal digits with colons separating each group like so:

• 2000:0000:0000:0000:0457:ACFD:45CB:230B

First leading zeros within a group can be omitted. For example 0457 can be written as 457. Also, successive groups of zero bits can be replaced by a pair of colons as “::”. This substitution can only take place one time in an address. Using the above example: 2000:0000:0000:0000:0457:ACFD:45CB:230B can be replaced with:2000::457:ACFD:45CB:230B.

In a compressed IPv6 address representation, to be able to resolve its fully qualified representation, you can count the number of groups in the compressed address, subtract this number from 8, and then multiply the result by 16. The result will be the number of bits represented by the “::”.

For example, in the address 2000::457:ACFD:45CB:230B, there are five blocks. The number of bits expressed by the “::” is 48 or (8 – 5) x 16. Each group is represented by 16 bits, hence 3 (48/16) groups of leading “zeros” are represented by the “::”.

The difference IPv6 address types include:

• Unicast – one-to-one
• Multicast – one-to-many
• Anycast – one-to-nearest

Note: Broadcast address scheme is not defined in IPv6; broadcasting as known in IPv4 is performed using multicast address in IPv6.

Unicast address type is the most common IP address type that is assigned to individual interfaces. It is divided into various types of unicast addresses according to their purpose. The most important ones are: IPv6 Global Unicast Addresses, Link-Local Addresses, and Special Addresses. Details about these addresses can be found in RFC 2373.

IPv6 Global Unicast Addresses are also known as Aggregatable Global Unicast Addresses, identified by the Format Prefix of 2000::/3 through E000::/3, with the exception of FF00::/8. These addresses are equivalent to public IPv4 addresses. By default, the number of bits used to identify the subnet is 64 and the number of bits used to identify the host on the subnet is again 64. At the ISP, or organization boundaries, these addresses can be aggregated hence limiting routing table entries.

The 64-bit host identifier in an IPv6 address is derived from the underlying link layer address (MAC address) of an interface. For mapping of MAC addresses into Interface identifiers in IPv6 global unicast and other addresses, Extended Universal Identifier (EUI) is used. The 64-bit EUI format is derived from the 48-bit MAC address by inserting the hexadecimal number FFFE (16 bits) between the upper 3 bytes and the lower 3 bytes of the MAC address, and setting the 7th bit of the leftmost byte to 1.

To Sum It All Up …

The benefits from IPv6 are huge. Although it’s a new technology, it is expected to grow exponentially and eventually completely replace IPv4. The new IPv6 is able accomplish more for several reasons:

• It makes NAT and its drawbacks obsolete
• It covers the IP addressing needs of every IP device on the planet
• It’s ideal for supporting new generation services
• Supports mobility
• Provides security
• Serves in the greater extend the strict quality requirements of broadband services

The transformation to IPv6 will not be completed overnight. It will take some years during which coexistence of IPv4 and IPv6 will be common, however IPv6 will eventually dominate.

I will try to make your life a little easier by introducing the idea of IPv6 to you. I will show you the IPv6 format, talk about compressions that you can use, and show you how to convert IP version 6 address into IPv4.

IPv6 Format

Let’s start with simple explanation of the new format. As you may know, the new-generation-IP talk started in the early 1990s when we were slowly running out of IP addresses. We had quite a few proposals for the new address format but in 1995 IPv6 was selected and the RFCs were officially entered into the RFC repository.

IPv6 was created based off of IPv4 with some of the useful IPv4 features carried over to IPv6. There were many changes to the new IP format, however, and I will list some of them here below.

• Expanded Addressing Capabilities: IPv6 address size increased from 32 bits to 128 bits. Because of the increased size the new address will support a higher number of nodes, more levels of addressing hierarchy, and a much simpler autoconfiguration of addresses for remote users. A new address type was created, called anycast.
• Header Format Simplification: To simplify the entire IP format, some of the IPv4 header fields were dropped or made optional in IPv6.
• Flow Labeling Capability: There is a new quality-of-service (QOS) capability that enables the labeling of packets belonging to particular traffic “flows” with special handling, such as real-time service.
• Authentication and Privacy Capabilities: There are new built-in extensions to support security options

Here is an example of an old and new addressing scheme:

     Old – IPv4 address:     129.14.12.200

     New – IPv6 address:     1029:9183:81E2:0000:0000:01D5:2115:019B

As you can see the new generation IP address is quite different from what we are used to. The IPv6 address is in a hexadecimal format. The only good thing in the IPv6 address format is that we can use compressions. There are rules, however, on how and when to use them.

Zero Compression

If you have consecutive fields of zeroes in the IPv6 address, you can express them with two colons.

It does not matter if you have two, three, four or eight fields of zeros, you can simply type two colons next to each other and that will represent all the consecutive zeros fields. These fields of zeros must follow each other.

A very important key to this rule is that you can only use that compression once in an IPv6 address. For example:

     Original IPv6 format:          1234:1234:0000:0000:1234:0000:0000:1234

     Using zero compression:     1234:1234::1234:0000:0000:1234

Notice how I used zero compression only ONCE in this example. Writing this address like this:

1234:1234::1234::1234

would make this address incorrect and every router would give you an error.

Leading Zero Compression

In a leading zero compression you can drop leading zeros in an address, in any field, as long as there is at least one number left. What that means is that if the address field is all zeros, you must leave at least one zero in that field. Here is an example:

     Original IPv6 format:                       1234:0000:1234:0000:1234:0000:0123:1234

     Using leading zero compression:     1234:0:1234:0:1234:0:123:1234

You can also combine these compressions and use them together in an address:

     Original IPv6 format:          1234:0000:0000:1234:0002:0033:0012:0123

     With both compressions:     1234::1234:2:33:12:123
     (zero and leading compression)

Zero Compression uses the double-colon to replace the second and third block of numbers, which were all zeroes. Leading zero compression replaces the “0s” at the beginning of each of the last four blocks. Just be careful and take time when using both zero compression and leading zero compression. They key is to remember that you can use zero compression only once in a single IPv6 address.

IPv6 to IPv4 conversion

1. Lets start with an IPv6 address that can be converted to IPv4:IPv6 address:     ::D190:4E71 – the double colon is zero compression
2. Since the IPv6 is in a hexadecimal format we will start with the first number, which is D1 and convert that into decimal. In hexadecimal D=13 and 1=1, so we have:D1 – 13 units of 16 and 1 unit of 1 = 209
3. The second number is: 90. Therefore we have:90 – 9 units of 16 and 0 units of 1 = 144
4. Next number is: 4E.4E – 4 units of 16 and 14 units of 1 = 78
5. And the last number: 71.71 – 7 units of 16 and 1 unit of 1 = 113
6. IPv4 address after conversion is: 209.144.78.113