Task 9.30 - Ping from R3 does not work
For those who stumbled upon this - ping to R4 and R5 from R3 via 6to4 tunnel does not work.
There is OSPFv3 enabled between R3 and R5 and we enabled "redistribute connected" in previous tasks under OSPF on R5. For this reason R3 will use longer prefixes than our 2002::/16 and tunnel interface is not preferred as the outgoing interface to reach remote IPv6 islands.
Rack1R3#sh ipv6 route ospf | in 2002
OE2 2002:9601:505::/64 [110/20]
OE2 2002:9601:505:1::/64 [110/20]