Making a Debut with IPv6 Part1 Preparing for IPv6 Connection

Takeshi Kabata



IPv6 has been said to make a splash in the society, but at least my father doesn't know what it is yet. One of the reason may be that not many people have experienced the fun of trying out IPv6. Merely connecting to IPv6 network as a client doesn't lead to long lasting fun.

This series of articles attempts to tell you how to use IPv6 to serve information and communicate with other Internet hosts. I hope you will find IPv6 a great fun at the end of the articles.

You are not required to know much about IPv6. Just try it out!


Before Preparing for Connection

Let's review some IPv6 words that you need to understand to read through this article. If you want more details, read relevant articles.

• IPv6 Address Expression
  128-bit IPv6 address is devided into eight 16-bit blocks, and expressed in hexacadecimal numbers (eg. fe80:b0c0:fab0:d0c1:b0f0:eff0:1c4e:13ef). Series of zeroscan be shortened, so that fe80:b0c:0000:0000:0000:0000:1c4e:13ef can be expressed as fe80:b0c::1c4e:13ef.
  
  The how do we express the port number? In IPv4, we can say 192.168.1.1:80, for example. In IPv6, ":" has a different meaning, so we would use brackets and say [fe80:b0c::1c4e:13ef]:80, for example. We may use "%"+number at the end of an address, like fe80:b0c::1c4e:13ef%3. In this case, the last number is called interface number or scope ID, indicating which network interface to use. Interface number may appear before the address, as in 3/fe80:b0c::1c4e:13ef.
  
  
• Loop-back Address
  The equivalent of IPv4 127.0.0.1 (localhost) is ::1 in IPv6. The address fe80::1, a "link-local" address, is used often.
  
  
• AAAA Record
  Let me briefly explain IPv6 DNS. When you ask IPv4 DNS the address of a host name "www.impress.co.jp", you get an IPv4 address such as 210.173.173.19. This is called A record. In IPv6, when you make a query on a host www.iij.ad.jp to a DNS server, you get two addresses returned, such as:
  
  www.iij.ad.jp AAAA IPv6 address = 2001:240::80
  www.iij.ad.jp internet address = 202.232.2.10
  
  This AAAA IPv6 address has the same role as A record in IPv4. AAAA reads "quad A". 1 host name can have one IPv4 address and one (or more) IPv6 addresses.
  
  
• Protocol Number
  TCP, UDP, and others are called protocols. These protocls are given "protocol numbers"(not port numbers). Protocol number of TCP is 6, UDP is 17, and IPv6 is 41. Not all current routers cannot pass protocol 41. A similar example is VPN. Some routers support "VPN pass through", which means they can pass protocols such as ESP and AH.

Things Needed for IPv6 Connection

Things you need to get connected to IPv6 are not so much different from IPv4. You may need hardware with "IPv6 support" depending on connection method. But in this series of articles, you are not required to buy new things, or drastically change current environment. We assume your current environment to be like Figure 1. An ADSL modem or broadband router connects your home PCs to the Internet, allocating IPv4 addresses by DHCP. Current router packet filtering basically shuts out communications initiated outside, while allowing all internally-initiated communications. No DMZ is configured for a server on this home network. We will use a Windows XP Professional PC for our experiment. We will try:

• live media streaming
  
• IPv6 Web server
  
• one-on-one chat

Figure 1 Network environment for the article


Installing Advanced Networking Pack for Windows XP

At first, you need to install Advanced Networking Pack for Windows XP. This component enables better support of IPv6 in Windows XP, and will be included in Windows XP SP2. For details, see "Advanced Network Pack for Windows explained Part 1 Teredo enables more transparent IPv6 connection". We will use Teredo, a new capability offered in this component.

• Downloading Advanced Networking Pack for Windows XP
  

Double click on the component downloaded from the above URL to install. After installation, click on Install button on Network Protocol Property (Figure 2). Choose Protocol on Network Components (Figure 2) and then choose [Microsoft TCP/IP version 6] (Figure 3). After successful install, you see [Microsoft TCP/IP version 6] on Network Protocol Property.

Then type "ipconfig /all" on command prompt, and you find some information that reads like IPv6 addresses. You don't have to see the details. If you see only IPv4 addresses, check if you specified "/all" in your command. Also check to see if IPv6 is added to Network Protocol (Figure 5).


Figure 2 Network Protocol Property (before TCP/IP version 6 install)


Figure 3 Choosing network component to add


Figure 4 Choosing network protocol to add


Figure 5 Network Protocol Property (after TCP/IP version 6 install)


Teredo and 6to4

If you are connected to the Internet directly, you can access IPv6 Web sites as soon as you have finished installing Advanced Networking Pack for Windows XP and IPv6. Access www.v6.imasy.or.jp and you can see your own addresses. If you are connected with IPv6 you see something like Figure 6.If you are connected with IPv4, you see something like Figure 7. If you access http://www.kame.net with IPv6, you see a dancing turtle.

You can access IPv6 sites because your PC has been given an IPv6 through a method called "6to4". Input "ipv6 if 3" on command prompt, and you see the current IPv6 address. In this case, "3" is an interface number, and allocated to 6to4.6to4 can be used very easily, but it has a major disadvantage. Your PC needs to have IPv4 address allocated. If you are using NAT, you need to configure the router so that your PC gets the global address allocated.

6to4 is the most popular technology to enable IPv6 communications with IPv4-only PC. But other technologies are being developed to overcome its short comings (see "A Discussion on IPv6 Transition Mechanisms Part2 Teredo, NAT-PT, BIS and MPLS" and other articles).

Here, we use Teredo, another technology from Microsoft. Put it simply, Teredo tries to traverse NAT by encapsulating IPv6 data in UDP packets. Although it is a complex technology, it is easy to use. You only need to issue the following command.

C:\ > netsh interface ipv6 set teredo client teredo.ipv6.6wind.com 30

This command allows connection to IPv6 network from PCs behind NAT. You can see dancing turtle at http://www.kame.net.

In the next article in this series, we will set up a public Web camera server. Please get a cheap Web camera and a microphone, if possible.



Figure 6 www.v6.imasy.or.jp connected via IPv6


Figure 7 www.v6.imasy.or.jp connected via IPv4


Caution
Install of IPv6 protocol may cause some hickup in Web browsing by Internet Explorer. The issue is related to DNS. When you input URL, DNS is searched to find the address of the host. If AAAA record is found on the host, Internet Explorer attempts to use this address before it uses A record. This is not an issue when end-to-end IPv6 connectivity is available. But if IPv6 connection fails, it may cause some delay in falling back to A record and access IPv4 site. This is a normal behavior for Internet Explorer and we can do nothing about it.

This problem may last for a while even if you get IPv6 uninstalled. A reason might be DNS local cache. Try clearing Internt Explorer cache and restart your PC.

A Useful Tip You may get connected with IPv4 even if the accessed site has both IPv4 and IPv6 addresses. There is no setting in Internet Explorer to force IPv6 connection. But you can do gthe following to assure IPv6 access. Use nslookup to see the IPv6 address of the site you want to access (we call this site www.v6.hogehoge.co.jp) Find a hosts file under system directory (C:\WINDOWS\system32\drivers\etc\hosts) Open this file with memo pad and add a new entry 2002:xxxx::yyyy www.v6.hogehoge.co.jp Save and close the file Access www.v6.hogehoge.co.jp with Internet Explorer