So I'm attempting to get ipv6 setup. I've followed the guide given here (https://library.linode.com/networking/ipv6) but have apparently hit across an issue I'm not sure how to solve.

Firstly I enabled ipv6 in my linode panel. Then I rebooted (I've done this a few times since then). The first thing of the guide says to run an ifconfig and see whats running.

eth0      Link encap:Ethernet  HWaddr f2:3c:91:93:ab:10  
          inet addr:178.79.129.240  Bcast:178.79.129.255  Mask:255.255.255.0
          inet6 addr: fe80::f03c:91ff:fe93:ab10/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1187116 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5038996 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:148229485 (148.2 MB)  TX bytes:836791944 (836.7 MB)
          Interrupt:76 

You'll notice my output is slightly different in that it doesn't have a Scope:Global address. Scanning further through the document I see that I need to assign an IP from my /64 pool to the interface so I do that

eth0      Link encap:Ethernet  HWaddr f2:3c:91:93:ab:10  
          inet addr:178.79.129.240  Bcast:178.79.129.255  Mask:255.255.255.0
          inet6 addr: fe80::f03c:91ff:fe93:ab10/64 Scope:Link
          inet6 addr: 2a01:7e00::f03c:91ff:fe93:ab10/64 Scope:Global
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1188011 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5039934 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:148316326 (148.3 MB)  TX bytes:836996085 (836.9 MB)
          Interrupt:76 

W00t. There is now a global address. In theory I'm now up and running right?

user:~$ ping6 ipv6.google.com
connect: Network is unreachable

Ah. Apparently not.

Some other information

user:~$ ip -6 route show
2a01:7e00::/64 dev eth0  proto kernel  metric 256 
fe80::/64 dev eth0  proto kernel  metric 256 

user:~$ sudo ip6tables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination 

I've tried all sorts of alternate ways of adding routes and addresses but none of them seem to have worked. I'd really like to get this running. Any hints?

So. The one thing I didn't try - and just did - worked.

iface eth0 inet6 static
        address 2a01:7e00::f03c:91ff:fe93:ab10
        netmask 64
        gateway fe80::1
        dns-nameservers 2a01:7e00::2 2a01:7e00::3

Setting the connection up as a static rather then autoconfigured one seems to do the trick just fine.