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IPv6 in a typical private network?
![[ca]](/s/countries/ca.gif) Shadow Hawkins on Monday, 24 March 2008 19:26:33
I am slowly learning what I can about IPv6 and at the point where I have a working IPv6 environment, sufficient for two computers to talk to each other and other IPv6 networked computers.
What I am interested in, is how some of today's IPv4 network scenarios will play out in an IPv6 world:
The most basic case is that of a home network. Currently an ISP provides a single IPv4 address to a subscriber. The subscriber can then, with the help of a DSL/router and NAT support as many computers as the private address range will allow, whether or not the provider officially allows this. Additionally the router will provide an address for each computer which asks for it and the addresses of both the gateway and the DNS server. How would this play out in a pure IPv6 world and also in the more realistic IPv4/IPv6 world?
Additionally I have heard the there shouldn't be a need for DHCPv6, so without an understanding of an IPv6 implementation of the scenario mentioned above, I am not sure what to make of this.
IPv6 in a typical private network?
![[de]](/s/countries/de.gif) Carmen Sandiego on Monday, 24 March 2008 21:51:04
If your provider offers you IPv6 access it would certainly be a /48-/64 network and not only one IP.
When you have one IPv4 address and a IPv6 subnet you have the following options:
a) Each host has a private IPv4 address and a public IPv6 address. If you access an IPv4 host it will use the NAT just as in a IPv4-only environment, IPv6 will have end-to-end connectivity.
b) The hosts only have a IPv6 address and you use a proxy on the router or use NAT-PT ( http://en.wikipedia.org/wiki/NAT-PT ) to access IPv4 nodes.
c) Only use IPv6 and IPv6 accessible servers (not feasible for a long time)
IPv6 in a typical private network?
Shadow Hawkins on Monday, 24 March 2008 22:26:41
So if I understand I get a range of addresses I can assign to my own devices? Also, would it be encourage for ISPs to provide static address prefixes to their customers?
If my router now has been configured with this block, what technology will it use to assign the addresses to the computers in the network and tell them about the DNS that they should be using? Is DHCPv6 the way to go, or is there something else?
IPv6 in a typical private network?
![[si]](/s/countries/si.gif) Shadow Hawkins on Tuesday, 25 March 2008 11:24:24
Read this in the FAQ, it describes more or less exactly this type of setup : https://noc.sixxs.net/faq/connectivity/?faq=usingsubnet
To answer your questions:
- yes, you get a range of addresses
- addresses are static
- as described in the FAQ entry above, the radvd on the router assigns correct settings (addresses) to the connected host on the LAN
Note:
- the above is true for SixXS, other providers might behave differently
- with SixXS, you first get a single address, one week later you can ask for an address range
- the above setup does not handle DNS settings, as far as I know. In my own network I also have IPv4 and the IPv4 DNS server resolves IPv6 addresses. It seems at least Windows uses some default values for DNS server, which might work. Otherwise DHCP6 might be required. Notice that this about DNS is all guessing from my side.
IPv6 in a typical private network?
Shadow Hawkins on Tuesday, 01 April 2008 17:20:14
Thanks for the information. Getting my own subnet from SixXS helped me understand the differences between the IPv4 setup and the IPv6 setup.
DNS server discovery seems to depend on a IPv4 DHCP solution for the moment. This seems to be an okay solution in the short to medium term, but I'll have to see if there is a long term solution.
IPv6 in a typical private network?
![[nl]](/s/countries/nl.gif) Shadow Hawkins on Tuesday, 01 April 2008 18:00:50
Currently Windows XP uses the following DNS addresses as default:
fec0:0:0:ffff::1
fec0:0:0:ffff::2
fec0:0:0:ffff::3
In Windows Vista, someone is able to specify an DNS address, without interfering with IPv6 Auto discovery.
But now I have a question, is it save to give a DNS server also a fec0:0:0:ffff::1 address without braking any routing through SixXS???
IPv6 in a typical private network?
![[se]](/s/countries/se.gif) Shadow Hawkins on Tuesday, 01 April 2008 21:45:00
hmmm, seems to be something Microsoft would be a good default when it comes to IPv6 networks when Site-Local Addresses were still non-deprecated... i wonder if a future service pack will change that behaviour into something more usable.
Since now those addresses makes no sense at all.
IPv6 in a typical private network?
Shadow Hawkins on Tuesday, 01 April 2008 21:54:57
I just checked with Windows Vista, if no v6 DNS is configured only v4 is used.
So I guess in XP this will be removed in the future, but now the question, how to setup IPv6 DNS in XP.
IPv6 in a typical private network?
Shadow Hawkins on Wednesday, 02 April 2008 21:35:03
As far as i know it's impossible. atleast that was quoted at the IETF IPv4 blackout event :|. They had to run a local DNS server on the WinXP clients. and do DNS over IPv4 on localhost and the DNS server would cache/resolve domainnames using it's own list of IPv6 DNS servers.
IPv6 in a typical private network?
Shadow Hawkins on Thursday, 03 April 2008 14:45:53
RFC 4339 - IPv6 Host Configuration of DNS Server Information Approaches
This gives some hints about DNS server (non)configuration.
DNS is a service above the IP layer, so it wasn'r really considered in all the autoconf stuff...
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