How to get IPv6 working?

[_corruptor]

Hi all,

I have two calls for help.

Spoiler

Requestt 1:  Getting ipv6 to work

I cannot get IPv6 working.  My HH6 router tells me that I have an ipv6 address but test-ipv6.com says I have no access to the ipv6 internet.

A [heavily redacted] set of pictures tells the story of a thousand words, so here goes.

After choosing the reset option in the HH6, here is the ipv6 status page

And the next tab:  The ipv6 Configuration page, which is at default settings:

Next, here's what the PC Wi-Fi adapter has:

Wireless LAN adapter WiFi:

   Connection-specific DNS Suffix  . : lan
   IPv6 Address. . . . . . . . . . . : 2a00:xxxx:xxxx:xx01::192
   IPv6 Address. . . . . . . . . . . : 2a00:xxxx:xxxx:xx01:bc9c:b1f:802f:472
   Temporary IPv6 Address. . . . . . : 2a00:xxxx:xxxx:xx01:d13c:c679:1055:1416
   Link-local IPv6 Address . . . . . : fe80::xxxx:xxx:xxxx:172%3
   IPv4 Address. . . . . . . . . . . : 192.168.x.x
   Subnet Mask . . . . . . . . . . . : 255.255.x.x
   Default Gateway . . . . . . . . . : fe80::xxx:xx:xxxx:xxxf%3
                                       192.168.x.x

And finally a report from test-ipv6.com

Spoiler

Request 2

Request 2 adds some complexity:  Behind the HH6 I have an old ADSL router running OpenWRT, which is NATted for ipv4 (and working well).  The main reason I have this is because my internal network configuration is held here and it's the path of least resisance to keeping my internal network as-is.

From reading up on BT's IPv6 offering, we residential customers each get a dynamic delegated /56 prefix.  That means I should be able to use OpenWRT to offer one of the subnet blocks, right?

The OpenWRT box has two vlans/interfaces, one for the Internet (a wired connection to HH6) and the other for the lan. So does anyone know the correct way to configure it is?

Thanks in advance,

---

Steven

[smf22]

For request 1:

The Hub has an IPv6 address and looks OK. Assuming the redacted prefix you see on the Hub is the same as you see on the client, the Hub would also seem to be advertising that prefix to the clients. Are you able to get any IPv6 connectivity e.g., ping -6 www.google.com? If you run the command route print on the client, does it see a default (::/0) route? Can you ping -6 to the link local (fe80) address seen as the next hop for the default route? Note that when you ping a link local address you need to add %x to the end of the IPv6 link local address where 'x' is the interface number seen in the route print output.

For request2:

The BT Hub uses DHCPv6 Prefix Delegation to get the /56 prefix from an 'upstream' BT 'delegating router'. In this way the Hub is operating as a DHCPv6 client.

To offer one or more of the 256 prefix from within the /56 prefix to a downstream router e.g., the OpenWRT router, would mean the Hub would have to be a DHCPv6 server offering the prefix it had been delegated.

Looking at the IPv6 Router Advertisements the Hub sends on the LAN, I'd say the BT Hub has DHCPv6 server capability. That said, I'm not aware that it allows 'onward' prefix delegation, and there are certainly no configuration options.

It should be noted that Sky, whose IPv6 story is more mature, do not offer this either. I saw the UK IPv6 Council presentation from Sky that they may consider it in the future, but not today. I've not seen any similar statement from BT.

If you're already using a non BT router, why not simply drop the Hub completely and keep the control you want in that way? This should simply be a case of adding a VDSL capable modem (assuming Infinity) in front of the OpenWRT router.

Regards

[_corruptor]

Hi Smf22, thanks for the quick reply.

For Request 1:

I checked that the prefix on the hub was the same as on the client, and it was.  Then I used the traditional fix for broken IT gear and found that the reboot of the router and of the client PC sorted the issue.  So that's Request 1 sorted.

For Request 2:

If I understand IPv6 correctly - which is a tenuous consideration since I only have enough knowledge to be dangerous - it seems a waste of a /56 if only one of the 256 subnets will ever be used.  I speculate that they are reserving the others for future use.

If I understand your last post correctly: I think you are saying that there is no prefix delegation from the BT hub because it's dhcp6 server is - ahem - crippled, therefore I ought to buy a new VDSL Router which features a dhcp6 server that DOES offer prefix delegation?  If so it looks like I'll need to do a fair amount of homework!

In the meantime, is it possible to pick an arbritrary subnet out of the allocated /56 and give the lan port a static address, then configure ipv6 routing to make it work?  I know that the prefix is dynamic but a cunning script on OpenWRT would be able get around that.

Yes, it's Infinity.  I recently upgraded from ADSL and the increase in speed is phenomenal!  🙂

Thanks.

[smf22]

Glad you have IPv6 working again.

You're right that it might seem delegating a /56 to be a waste, but BT are following best practice advice and thinking to the future. Today the Hubs only have one LAN interface, but the Hubs are perfectly capable hardware, and so it's possible in the future more may be provisioned e.g., for the Internet of Things.

To be honest I'm not aware of any routers that allow onward delegation. I've a very functional Ubiquiti router (Debian based) and I've yet to figure out how this would do it. Not that I want to 😁

Whilst there's nothing to stop you using any one of the unused prefix on a downstream router, I think the problem you'll have is letting the Hub know. There's no way to configure the Hub with the routing required for it to know that the IPv6 address assigned to your OpenWRT router is the 'next hop' to the prefix you've 'borrowed' to use on the OpenWRT router.

I still think giving up on the Hub 6 is the way to go. All ISP router are simply too locked down to do anything useful. Get an old Openreach modem from the well known auction site and use the OpenWRT router connected to it in place of the Hub 6.

Regards

[Checked2013]

I have no issues at all with IPv6 on my smarthub as can be seen from the screenshot

[smf22]

Nor does @_corruptor now, but wants to do more than the Hub currently allows.

Regards

[smf22]

Although if I were being pedantic, you wouldn't get 100% on some other IPv6 test sites as BT does not currently support IPv6 on their DNS servers.

Regards

[_corruptor]

Thanks @smf22 I think you're right:  A swanky new router is in my near future  😄

[Checked2013]

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@smf22 wrote:
Although if I were being pedantic, you wouldn't get 100% on some other IPv6 test sites as BT does not currently support IPv6 on their DNS servers.

Regards

---

Can you give an example of one of these sites? As all the sites I've tried have passed 100%

[smf22]

@Checked2013: Perhaps somethings changed for the better with the BT DNS servers. It always used to be that the last test at http://test-ipv6.com/ would fail when using BT DNS servers.

I assume your clients are using DHCP from the Hub and so using the name servers at 81.139.56.100 and 81.139.57.100?

I haven't used the Hub 6 or BT DNS servers for many months now so wouldn't have noticed any change. Thanks for letting me know.

Regards