I've got IPv6 addresses from SIXXS. My host is connected with SIXXS network over a AICCU tunnel ("sixxs" interface). My host address is 2001:::2, the host on the end has address 2001:::1. On my host IPv6 is fully accessible. I have problem with configuring IPv6 network on VMs. I use VirtualBox, the VM (Ubuntu) uses tap1 (on the host bridged by br0) #!/bin/sh PATH=/sbin:/usr/bin:/bin:/usr/bin:/usr/sbin # create a tap tunctl -t tap1 ip link set up dev tap1 # create the bridge brctl addbr br0 brctl addif br0 tap1 # set the IP address and routing ip link set up dev br0 ip -6 route del 2001:6a0:200:172::/64 dev sixxs ip -6 route add 2001:6a0:200:172::1 dev sixxs ip -6 addr add 2001:6a0:200:172::2/64 dev br0 ip -6 route add 2001:6a0:200:172::2/64 dev br0 Host: routing table: 2001:6a0:200:172::1 dev sixxs metric 1024 2001:6a0:200:172::/64 dev br0 proto kernel metric 256 2001:6a0:200:172::/64 dev br0 metric 1024 2000::/3 dev sixxs metric 1024 fe80::/64 dev eth0 proto kernel metric 256 fe80::/64 dev sixxs proto kernel metric 256 fe80::/64 dev br0 proto kernel metric 256 fe80::/64 dev tap1 proto kernel metric 256 default via 2001:6a0:200:172::1 dev sixxs metric 1024 Guest: interface eth1 (it is connected with tap1): auto eth1 iface eth1 inet6 static address 2001:6a0:200:172::3 netmask 64 gateway 2001:6a0:200:172::2 Guest: routing table 2001:6a0:200:172::/64 dev eth1 proto kernel metric 256 fe80::/64 dev eth0 proto kernel metric 256 fe80::/64 dev eth1 proto kernel metric 256 default via 2001:6a0:200:172::2 dev eth1 metric 1024 The guest pings to the host, the host pings to the guest, the host pings to 2001:6a0:200:172::1, but the guest doesn't ping to 2001:6a0:200:172::1. The guest tries to ping, on the host (by tcdump) I can capture its packets, but the host doesn't send them to 2001:6a0:200:172::1. What have I missed in configuration?