IPv6 Alive

There are already a surprising number of global test networks and even commercial networks running over IPv6. I discuss some interesting examples in the next sections. In order to describe what they are doing, I use some IPv6-specific terms that are probably not familiar to you yet. They are all explained in this book.


In February 2002 over 120 production networks have been allocated IPv6 address prefixes. For a current list, refer to http://www.dfn.de/service/ipv6/ipv6aggis.html.

The 6Bone

The 6Bone started out as a network of IPv6 islands working over the existing IPv4 infrastructure of the Internet by tunneling IPv6 packets in IPv4 packets. The tunnels were mainly statically configured point-to-point links. The 6Bone became a reality in early 1996 as a result of an initiative of several research institutes. The first tunnels were established between the IPv6 laboratories of G6 in France, UNI-C in Denmark, and WIDE in Japan.

Structure of the 6Bone

The 6Bone is structured as a hierarchical network of two or more layers. The top layer consists of a set of backbone transit providers, called pseudo Top Level Aggregators (pTLAs), which use BGP4+ as a routing protocol. The bottom layer is comprised of leaf sites connected via the 6Bone. Zero or more intermediate layers, called pseudo Next Level Aggregators (pNLAs), interconnect leaf sites and the pTLA backbone networks.


IPv6 unicast addressing of node interfaces (for both end systems and routers) is based on RFC 2374, which covers the Aggregatable Global Unicast address format. 6Bone backbone networks play the role of experimental TLAs, called pseudo TLAs (pTLAs), and assign address space to pseudo NLAs (pNLAs) and leaf sites. The prefix assigned to the 6Bone is 3ffe::/16 (RFC 2471). These pTLA backbone networks are currently allocated 32-bit prefixes (previously, 24- and 28-bit prefixes were allocated) that must be administered according to the rules defined for pTLAs. So every pTLA plays the role of an experimental top-level ISP and assigns chunks of its addressing space to directly connected transit and leaf sites without breaking aggregation inside the 6Bone backbone.


The 6Bone is growing fast. In December 1997 there were 43 backbone sites and 203 leaf sites registered. In December 1998 there were 51 backbone sites and 332 leaf sites. In January 2000 there were 67 backbone sites and 505 leaf sites.

I gave up on trying to find a nice picture of the world with the 6Bone backbone sites on it. The 6Bone has grown too big to display it in one screenshot. If you want to get a feeling for the size and workings of the 6Bone, go to http://www.cs-ipv6.lancs.ac.uk/ipv6/6Bone and look at the maps, statistics, and tools.

At the time of this writing, the number of nodes in the 6Bone has just reached 1000 nodes and grows daily. Find an updated list at http://www.cs-ipv6.lancs.ac.uk/ipv6/6Bone/Whois/index.html#full.

Joining the 6Bone

Membership in the 6Bone is open to anyone. Reasons for joining, besides the fun of it, would be to gain early experience working with IPv6, to build the expertise necessary to make decisions about when and how to use IPv6 for production networks, and to have working access to IPv6 servers and resources. Joining the 6Bone connects you with a cool crowd of people who want to be on top of technology and are willing to share their experience.

The 6Bone community spans the globe and is very active and enthusiastic. By joining, you not only gain access to the network and the common experience of those in it; you can also participate and help develop protocols, programs, and procedures.


If you are interested in joining the 6Bone, here’s the link: http://www.6bone.net/6bone_hookup.html.

There are different ways for you to connect to either the 6Bone or production IPv6 networks:

  • Become an end site of an existing 6Bone ISP (which means you will get your 48-bit IPv6 external routing prefix from that ISP’s TLA). You can also get temporary address allocations from tunnel broker sites (see the 6Bone home page for more information).

  • Apply for your own 6Bone TLA (if you are an ISP) based on the 6Bone process.

  • To get your first production IPv6 address, find a production IPv6 ISP (i.e., an ISP that has a sub-TLA) from which to get your prefix. Note that you can partially qualify for a sub-TLA production prefix if you have a 6Bone pTLA prefix (at least during the early phase of production prefix allocation).

  • Use the “6to4” automatic tunneling mechanism. This allows you to specify the IPv4 address of your end user site router for an IPv6-over-IPv4 tunnel to reach your end user site. Addresses of this type have the first 16 bits of 2002::/16, with the next 32 bits containing the IPv4 address of a router on your site supporting this mechanism (thus making up the entire 48-bit external routing prefix). Refer to Chapter 10 for more information on the “6to4” automatic tunneling mechanism.

Now all you really need is a router and a host running IPv6 stacks. Almost all router vendors have either production stacks or beta stacks available. Refer to http://playground.sun.com/pub/ipng/html/ipng-implementations.html for a list of router and host implementations.

Obviously you need an entry point into the 6Bone. Try to find one that is close to your normal IPv4 path into the Internet. You can find a good 6Bone TLA on the 6Bone home page at http://www.6bone.net/6bone_pTLA_list.html. Use traceroute to determine the closest path.

IPv6 Commercial Networks

Since I started writing this book, a lot has happened in the development of IPv6. There are many production networks worldwide that have already been assigned IPv6 address prefixes. We picked four examples of companies that made their step into the future by offering IPv6 services.


vBNS+ is a specialized US IP network that supports high-performance, high-bandwidth applications. The vBNS+ network supports both native IPv6-over-ATM connections and tunneled IPv6-in-IPv4 connections. The vBNS+ service has been assigned its own sTLA from ARIN, as well as a pTLA for the 6Bone, and is delegating address space under these assignments to vBNS-attached sites. For more information, refer to their site at http://www.vbns.net.

Telia Sweden

In summer 2001, Telia, in Sweden, announced its intention to build a new generation Internet based on IPv6. By the end of 2001, connection points were installed in Stockholm, Farsta, Malmoe, Gothenburg (Sweden), Vasa (Finland), Oslo, Copenhagen, and London.

I spoke with the project manager at Telia because I thought that his early adopter input might be interesting for companies that consider going into IPv6. Telia’s intent was to break through the lethargy of the chicken and the egg problem: vendors do not develop because the market is not asking for it, and the market doesn’t ask for it because vendors don’t develop. So Telia made the decision to create a market by building an IPv6 network and opening it to the public. Telia’s hope is that, through the publicity of its endeavor, other companies will follow suit, and the acceptance and development of IPv6 will increase.

At the current stage of its rollout, Telia is keeping the IPv6 network separate from the existing IPv4 infrastructure. There were different reasons for this decision:

  • It was easier to start by keeping the networks separate. Telia does not have to educate all of its IPv4 engineers to use IPv6 overnight.

  • If there are problems with the IPv6 network, the IPv4 network is not affected in any way.

  • It is less complex to configure if the networks are separate.

The new network is primarily built as a native IPv6 network. In some instances, tunnels over IPv4 are used. Currently, Telia is offering an IPv6 transport service to a limited number of customers. It will add features and gradually open the IPv6 network as a general service for everyone. Telia uses Hitachi routers that support IPv6 in hardware (versus software implementations).

After rolling out the first connection points, Telia concluded that market support for IPv6 was sufficient to get started. There are applications that will need to be ported to IPv6, but Telia recommends that companies and ISPs start right away. The foundation is here and when IPv6 is implemented on a broader range, vendors and application developers will be encouraged to speed up development.

Internet Initiative Japan

Another company that offers IPv6 transport services is Internet Initiative Japan (IIJ), Japan’s leading Internet access and solutions provider, which targets high-end corporate customers. IIJ offers a trial IPv6 service (tunneling through IPv4) and a native IPv6 service that is independent from existing IPv4 networks. In December 2001 IIJ extended its IPv6 services to individual users connecting through IIJmio DSL/SF, an ADSL Internet service.


For information about IIJ’s services, refer to http://www.iij.ad.jp/IPv6/index-e.html.

NTT Communications Corporation

NTT Laboratories started one of the largest global IPv6 research networks in 1996. Trials of their global IPv6 network, using official IPv6 addresses, began in December 1999. Since spring 2001, NTT Communications has offered commercial IPv6 services.

In April 2001 the company started their commercial IPv6 Gateway Service. This native IPv6 backbone service connects sites in Japan to the NTT/VERIO Global Tier1 IPv6 backbone deployed over Asia, the U.S., and Europe. Monitoring and operation continues 7 days a week, 24 hours a day, through NTT Communications NOC in Tokyo, Japan and Verio NOC in Dallas, US. Figure 1-1 shows the layout of the backbone.

NTT/VERIO’s global IPv6 backbone

Figure 1-1. NTT/VERIO’s global IPv6 backbone

The IPv6 Gateway Service offers native IPv6 transport. Also shown on the picture is the IPv6 Tunneling Service that NTT has offered since June 2001. It uses the existing IPv4 network to enable NTT’s partners to access the IPv6 network, using IPv6-over-IPv4 tunneling techniques via dedicated lines. The newest addition is the IPv6/IPv4 Dual Access point with plug-and-play functionality, which became available in the first quarter of 2002. It is shown in dotted lines on Figure 1-1. The first customers to use the native backbone service were BIGLOBE/NEC Corporation, CHITA MEDIAS NETWORK INC., Toshiba, InfoSphere/NTTPC Communications, Fujitsu Matsushita Graphic Communication Systems, Inc., and MEX/Media Exchange, Inc. In June 2001, NTT demonstrated applications running over IPv6, including a remote control camera running over IPv6 and videoconferencing using IPv6.

The routing protocols used are BGP4+ and RIPng, IS-IS (which will be on the global backbone in the near future), and OSPFv3 (which is used at NTT’s Japan domestic backbone). What NTT lacked was ICMPv6 polling in commercial operational tools. They utilize their own custom-developed router configuration tools and network management tools that support IPv6.

NTT offers Points Of Presence (POPs) all over the world, currently in London, Palo Alto, San Jose, Seattle, and Tokyo. They plan to extend their services throughout the world; the next POPs will be in Hong Kong and Australia. NTT’s services include official IPv6 addresses from their sTLA block, IPv6 Internet connectivity, and DNS reverse zone delegation for the subscriber’s IPv6 address space.


For an overview of NTT’s global IPv6 services and how you can participate and connect, refer to http://www.v6.ntt.net/globe/index-e.html.

Links to Other IPv6 Networks

There are a large number of international IPv6 test and research networks. You can find some interesting links in the following list:

The 6Ren

The 6Ren is a voluntary coordination initiative of research and education networks that provide production IPv6 transit service to facilitate high-quality, high-performance, and operationally robust IPv6 networks. Participation is free and open to all research and education networks that provide IPv6 service. Other profit and nonprofit IPv6 networks are also encouraged to participate. The 6Ren web site can be found at http://www.6ren.net.

The 6Net

The 6Net is a high-capacity IPv6 research network coordinated by Cisco, with more than 30 members. Their home page can be found at http://www.sixnet.org.


The Defense Research and Engineering Network (DREN) is a major component of the DoD High Performance Computing Modernization Program (HPCMP). Its purpose is to provide high-performance network connectivity to various communities of interest in the DoD, including research and development, modeling and simulation, and testing and evaluation. DREN also provides connectivity to other high-performance backbones and Federal networks to serve the needs of these communities. DREN is also a research network; it provides a test bed for testing new protocols and applications. DREN provides both ATM cell-based services and IP frame-based services. The DREN IPv6 network is one of the services provided as part of DREN. The DREN web site is at http://www.v6.dren.net.

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