IPv6 problems?

Is anyone else experiencing problems with their IPv6 connectivity at the moment?

Earlier today my line resynced and when a new PPPoE session was established my LANs no longer had IPv6.

The pfSense router itself has an address from its ND prefix and can ping6 hosts (just noticed bbc.co.uk now has IPv6), but no longer seems to be receiving a /48 prefix for LAN delegation.

It's possible that Zen's DHCPv6 server has gone down. As your /48 is static, it's perfectly in order to configure static prefixes on your LAN(s) - that's how I have my pfSense box configured.

bbc.co.uk has been dual stack for a while, but www.bbc.co.uk (which is a CNAME for www.bbc.net.uk) is still IPv4 only.

Unfortunately configuring static prefixes on my LANs didn't work. I've been on IPv6 since the trial so am not sure if this is still an issue.

The trial configuration was that Zen didn't install the route to the /48 until you delegated a prefix in that block from the DHCPv6 server. At the end of the trial, Zen decided to install a static route to the /48 in accounts newly enabled for IPv6, but the triallists' configurations were only changed if an individual triallist requested a change to the static route configuration by e-mailing [email protected] as the post you linked to explains.

I was a triallist, but requested the static route for robustness reasons after the DHCPv6 server outage that thread related to. Your experience suggests that the static route configuration has still not be retrospectively applied to those triallists who did not explicitly request it.

In reply to a post by David_W:

It's possible that Zen's DHCPv6 server has gone down. As your /48 is static, it's perfectly in order to configure static prefixes on your LAN(s) - that's how I have my pfSense box configured.

bbc.co.uk has been dual stack for a while, but www.bbc.co.uk (which is a CNAME for www.bbc.net.uk) is still IPv4 only.

Are you saying you don't use dhcp6 on the WAN request for an ipv6 address
I would be very interested in this approach as I need to use dhcp6 on my second WAN connection and its only possible to do it on one

In reply to a post by kwillers:

Are you saying you don't use dhcp6 on the WAN request for an ipv6 address
I would be very interested in this approach as I need to use dhcp6 on my second WAN connection and its only possible to do it on one

You can use DHCPv6 and DHCP-PD on multiple interfaces, but it sounds like your device does not support that type of configuration.

Unless things have changed, Zen uses SLAAC to give your WAN interface an IPv6 address - they will not do so over DHCPv6. If this is still the configuration, it is TR-187 compliant, as TR-187 allows SLAAC, DHCPv6 or both. If I remember correctly, you can also set any static address(es) you choose in the /64 block Zen allocate to you, though if you do this, using <your /64 prefix>::1 is usual.

The trial configuration was that a route to your /48 was not installed until you leased one or more prefixes to delegate to your local network using DHCP-PD. This was felt to lack robustness, so the post-trial configuration (to which triallists can be moved on request) is that a static route to the /48 is installed - if I remember correctly, to <your /64 prefix>::1 (in which case you should set this address statically on your WAN interface either as its main address or an alias alongside its SLAAC address). If Zen has added the static route to your configuration, you do not need to use DHCP-PD if you are happy to allocate prefix(es) statically to your LAN(s).

Thanks for that so If I'm reading correctly for Zen

On Interface WAN I would
- select"IPV6 Configuration Type" STATIC
- Set the ipv6 address to <my/64 prefix>::1 /64

On LAN I Would
- select"IPV6 Configuration Type" STATIC
- Set the ipv6 address to <my/48 prefix>:1234:: /64

Then I free to use dhcpv6 server to allocate the <my/48 prefix>:1234:: as need

Edited by deleted (Fri 21-Apr-17 10:44:33)

In reply to a post by kwillers:

Thanks for that so If I'm reading correctly for Zen

On Interface WAN I would
- select"IPV6 Configuration Type" STATIC
- Set the ipv6 address to <my/64 prefix>::1 /64

On LAN I Would
- select"IPV6 Configuration Type" STATIC
- Set the ipv6 address to <my/48 prefix>:1234:: /64

In principle, yes - but this will work if and only if your RADIUS record contains a static route for your /48 to <your /64 prefix>::1. If you are not sure, drop your PPP connection, disable DHCP-PD at your end, then bring PPP back up with the static configuration in place. If you have no routing to the /48, contact [email protected] and request a static route to the /48.

In reply to a post by kwillers:

Then I free to use dhcpv6 server to allocate the <my/48 prefix>:1234:: as need

You can allocate addresses on your LAN(s) using DHCPv6, SLAAC or both. Which addressing method is used depends on the flags in your RAs. Obviously, the configuration of your DHCPv6 server - if you are running one - must match your intended configuration.

Thanks Zen claim I am configured correctly but the above still does not seem to work.
I suspect user error

They are going to review their knowledge base and see if they can find the exact settings required as the few tries we did together on the phone did not work

I'm not clear from the post if you are using pfSense or just know about how to configure it.
If the former could you share your screen shots if you have any ?

I use pfSense here and have contributed various PPP and IPv6 fixes to pfSense.

I suspect you've got one key element of your configuration missing, which I will come to below.


I would set the "IPv6 Configuration Type" on your WAN interface to DHCP6, which in pfSense (at least as the code currently stands) means DHCPv6 and/or SLAAC. This means that you'll support both variants of WAN configuration listed in TR-187, though Zen only currently support SLAAC. This is a matter of robustness; it's best to accept whatever autoconfiguration Zen offers.


Whilst you're in the WAN interface, if you have a jumbo capable NIC on the WAN port and jumbo capable FTTx hardware (including either flavour of Openreach FTTP ONT and either flavour of Openreach FTTC modem), pfSense supports MTU 1500 over PPPoE using RFC 4638 from pfSense 2.3 onwards - just set 1500 as the WAN MTU. If this causes problems, clear the MTU field which will reset the MTU to the PPPoE default of 1492.

You can test whether the 1500 byte WAN MTU is working using Diagnostics->Command Prompt. Enter (without the quotes) "ping -D -s 1472 -c 4 forum.pfsense.org" in the "Execute Shell Command" box and press Execute. You should get some responses if you have MTU 1500 working. If IPv6 is working, you can additionally try "ping6 -D -s 1452 -c 4 forum.pfsense.org".


You then need to go into Firewall -> Virtual IPs. Create an "IP Alias" VIP on your WAN interface of <your /64 prefix>::1/128 - that allocates an additional address on your WAN port to go alongside the SLAAC address (N.B. it is generally regarded as best practice to allocate additional IPv6 addresses within an existing prefix on the interface as /128 - if you were configuring this address as the only address on your WAN interface statically, you would use /64). In addition, create an "Other" VIP on your WAN interface of <your /48 prefix>::/48 - this is the essential step that you are likely missing.

If you have an IPv4 netblock, you need an "Other" VIP of <lowest IPv4 address>/<allocated width> on the WAN interface - then you can use the additional addresses on your local networks using any combination of routed IP and NAT that you desire.


Let me know how you get on.