For completeness, ip commands to reproduce this:
host A:
ip link add gre-v6 mtu 1280 type ip6gre remote 2001:db8:1::1 local
2001:db8:2::1 ttl 64
ip link set dev gre-v6 up
ip a a 10.0.0.1/30 dev gre-v6
host B:
ip link add gre-v6 mtu 1280 type ip6gre remote 2001:db8:2::1 local
2001:db8:1::1 ttl 64
ip link set dev gre-v6 up
ip a a 10.0.0.2/30 dev gre-v6
host A:
ping -c 1 10.0.0.2
host B:
ifconfig gre-v6
gre-sbr: flags=209<UP,POINTOPOINT,RUNNING,NOARP> mtu 1280
inet 10.0.0.2 netmask 255.255.255.252 destination 10.0.0.2
inet6 fe80::84d2:c8ff:fea8:f43e prefixlen 64 scopeid
0x20<link>
unspec 2A-0D-8D-04-00-0B-00-01-00-00-00-00-00-00-00-00
txqueuelen 1000 (UNSPEC)
RX packets 0 bytes 0 (<redux>)
RX errors 1 dropped 0 overruns 0 frame 0
TX packets <redux> bytes <redux> (<redux>)
TX errors 8 dropped 8 overruns 0 carrier 0 collisions 0
<redux> for example use; reproduced (currently no hosts that have not
been rolled back.
