Trial status might be a little unfair as it implies that the service might be changed, withdrawn or liable to interruptions without warning. It is probably better to describe it as a soft launch.
In my experience, IPv6 connectivity is solid once established and connections from customers with IPv6 enabled are correctly redirected to gateways with IPv6 enabled.
I'm not sure what the situation is for the Manchester gateways, as I connect through London. Those on Zen backhaul connecting through London with IPv6 enabled can connect to bng1.th-lon, bng2.th-lon, also I think one of the older dslX.th-lon gateways still accepts connections from those with IPv6 enabled.
A large part of the problem with launching IPv6 on consumer broadband is the hit and miss quality of IPv6 support in customer routers. Even though Zen use a standard TR-187
configuration (WAN link-local address and gateway address (which is also link-local) via IPv6CP, WAN globally routable address via SLAAC from the static /64 allocation, LAN prefixes via DHCP-PD from the static /48 allocation), some people found they could not make IPv6 work during the trial.
Zen now add a static route for the /48 to </64 prefix>::1 on accounts newly enabled for IPv6, making it possible to set your WAN IPv6 address to </64 prefix>::1 and use whatever mix of static prefix allocation and DHCP-PD you choose on your LANs (though be aware that DHCP-PD will happily allocate a prefix that you've statically allocated to another LAN). Those whose accounts were enabled during the trial phase can have this static route added to their RADIUS record by e-mailing email@example.com.
Zen should be fairly quick to remove IPv6 elements if a customer wants to revert to an IPv4 only configuration. The best way is likely to e-mail firstname.lastname@example.org.
If anyone wants to experiment with IPv6 and can bridge their existing router, pfSense
should 'just work' on suitable x64 (preferred) or x86 hardware. I contributed RFC 4638 support, which appeared in pfSense 2.3, so MTU 1500 operation over FTTC and FTTP is possible with suitable hardware (both Openreach modems are OK for FTTC, though you do need a jumbo capable NIC for the pfSense WAN interface). I've contributed various IPv6 over PPP improvements in recent months.
The pfSense team are experimenting with an ARM build, though there's no news on a launch date or a complete list of which platforms will be supported.
It is a shame that there hasn't been any visible progress in IPv6 support since the launch. I know that it takes time to roll out IPv6 services but you'd think that ntp0.zen.net.uk could be enabled relatively quickly. The lack of a London based recursive DNS is also disappointing.
I run my own recursive DNS server and NTP servers (one has a GPS receiver with PPS support, so is stratum 1), so don't really notice these things. There are a fair number of IPv6 NTP servers in the UK pool.
For DNS, there's always Google's public DNS servers on 2001:4860:4860::8844 and 2001:4860:4860::8888. Google use load balancing and the actual locations of the responding servers are not always clear, but right now I'm getting around 6.5ms additional RTT than the Zen London gateway.