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Standard User Andrue
(knowledge is power) Sun 23-Jun-13 09:33:33
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That thing called IPv6

[link to this post]
So I've got IPv6 working - no problems there. But I run a mail and ftp server and I'd like to set my AAAA record up just so that I can say I've done it. My problem is that it's not clear how I set up static IPv6.

I decided the simple way would be to just fix my server at the address it's currently chosen. But that raises questions:

1. Is it going to change? MSDN says that the public address is picked randomly but seems to imply that once picked it's fixed. Would it be sensible to get it to build its address based on the MAC instead?

2. Does IPv6 auto configuration handle static addresses automatically? With IPv4 you either reserve the address in the router or just pick an address outside of the DHCP pool.

3. When I put the existing address, gateway and DNS values into Windows 7 it asks to reboot then loses IPv6 network connectivity. What's going on there?

Andrue Cope
Brackley, UK
Standard User yarwell
(sensei) Sun 23-Jun-13 10:12:04
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Re: That thing called IPv6

[re: Andrue] [link to this post]
my vague recollection is that the tail end of the IPv6 address is similar to (if not based on) the MAC address of the adapter concerned ?

so the "random" thing may be MS specific or indeed switchable.

The front end of it is obviously assigned by your ISP as the routable part to get to your network from elsewhere. may be helpful



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Edited by yarwell (Sun 23-Jun-13 10:15:43)

Standard User iand
(fountain of knowledge) Wed 26-Jun-13 18:19:23
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Re: That thing called IPv6

[re: Andrue] [link to this post]
ok, this advice will be wrong (its new to me too) but....

I think what you are getting is an automatic IPv6 IP address. You need to get your own IPv6 address from your provider and then pick one from that for your router and then your pc's. It could be your router will dish out a DHCP IP v6 address to the PC from your allocated address range just like v4.

I am going to have to start thinking about getting an IPv6 router and capable ISP to have a proper play around..


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Standard User prlzx
(experienced) Wed 26-Jun-13 20:35:00
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Re: That thing called IPv6

[re: iand] [link to this post]
Yes IPv6 host addresses can be assigned by DHCPv6,
or self-assigned - based on the MAC address, or something more random if using Privacy Extensions.

As I understand it, the LAN interface prefix is usually based on what was provided to the router from upstream (the ISP).

If the ISP provides a /64 that is one network and will be the LAN prefix.
If the ISP provides a /56 or a /48 that can be several subnetted networks so the LAN prefix can be a /64 taken from somewhere in that range, or on a router with multiple real interfaces (not the built-in switch), there can be another prefix used for the DMZ network.

So for the full address for the AAAA record, DHCPv6 reservation or based on MAC address will both give a fixed address (while with this ISP). Don't try to set a host IPv6 address by hand on the server itself (unless setting an address on a router interface), it is not worth the trouble when you'll have to set several long fields up exactly correctly, and you would still have to ensure the router knows about it not to hand out the same address to something else.
The protocols (including DHCP) exist to automate this.

And instead of NAT port forwarding from destination ports on the WAN IP of the router, one more directly configures the router firewall to allow requests to reach those ports at the actual destination (server). If the server itself is running a firewall the traffic needs to be allowed there as usual.

So for the sake of other readers in other words the AAAA record will be for a LAN address (or DMZ address if you have one) of the server and not the WAN address of the router as with IPv4 NAT and single public IP.

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prlzx on iDNET: ADSL2+ / 21CN at ~4Mbps / 700kbps with IP4/6

Edited by prlzx (Wed 26-Jun-13 20:51:45)

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