Recently I have installed Citrix Xen Server 6.2 on a machine. My Provider (Hetzner) gave me the IPv6 Subnet 2a01:4f8:200:xxxx::/64.

Followed an article in the providers wiki (1) i got it working and can assign IPs to my guests (CentOS). However i can't assign a second IP to a single guest - it will result in a timeout. I'm not very familiar with IPv6 routing / subnetting - any help or tips for further troubleshooting is welcome!

My Setup:

XenServer 6.2
IPv6: 2a01:4f8:200:xxxx::2/112
ip -6 route:

    2a01:4f8:200:xxxx::/112 dev xenbr0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 0
    fe80::1 dev xenbr0  metric 1024  mtu 1500 advmss 1440 hoplimit 0
    default via fe80::1 dev xenbr0  metric 1024  mtu 1500 advmss 1440 hoplimit 0

Guest 1
IPv6: 2a01:4f8:200:xxxx::3/64
IPv6: 2a01:4f8:200:xxxx::4/64
ip -6 route: 
    2a01:4f8:200:xxxx::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
    fe80::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440 hoplimit 4294967295
    default via fe80::1 dev eth0  metric 1  mtu 1500 advmss 1440 hoplimit 4294967295


Guest 2
IPv6: 2a01:4f8:200:xxxx::5/64

Guest 1 IPv6 is working fine, Guest 2 too.

As suggested by the wiki article (1) i split my /64 network into a /112. Is it right to set the host /112 and the guests /64? Why is that?