← All lab tasks IP Connectivity Fix · Medium ~15 min · 3 devices · 4 tasks · CCNA v2.0
OSPFv3 triangle: an IPv6 network with no neighbors Three routers are wired in a triangle and run OSPFv3 process 1 in area 0. The network is IPv6 only: there is no IPv4 address on any router. Right now show ipv6 ospf neighbor is empty everywhere. Addresses, cables and ipv6 unicast-routing are correct. Three OSPFv3 mistakes are hiding on three different routers. Fix them without changing any address, then prove R2 reaches R3’s loopback over their direct link.
R1 Gi0/0 2001:db8:12::1/64 to R2 Gi0/0 2001:db8:12::2/64
Tasks ○ R3 runs OSPFv3 with router ID 3.3.3.3 ○ R1 and R2 are FULL OSPFv3 neighbors ○ R2 and R3 are FULL OSPFv3 neighbors ○ R2 routes to 2001:db8:3::3/128 over Gi0/1 and ping 2001:db8:3::3 from R2 succeeds ✓ Network fixed.
All three faults fixed. Run show ipv6 ospf neighbor on R2 to see both neighbors as FULL/ -, then show ipv6 route ospf to see the link-local next hops.
Hints (open one at a time) Hint 1: where to start Run show ipv6 ospf neighbor on every router. R1 and R2 print an empty table, but R3 prints a message instead. Read it carefully.
Hint 2: R3 OSPFv3 carries IPv6, but its router ID is still a 32 bit dotted value. A router with no IPv4 address cannot pick one on its own, so the process never starts. Set it under ipv6 router ospf 1.
Hint 3: R1 to R2 On R1 run show ipv6 ospf interface GigabitEthernet0/0. A passive interface sends no hellos. Passive belongs on the user LAN (Gi0/2), never on a link to another router.
Hint 4: R2 to R3 Run show ipv6 ospf interface brief on R2 and on R3 and compare the Area column for the link between them. Both ends must be in the same area.
Hint 5: the last task Run show ipv6 route ospf on R2. The next hop is a link-local address. If 2001:db8:3::3/128 goes through R1 instead of Gi0/1, the direct link is still broken.
Full solution ! R3: give OSPFv3 a router ID
R3# configure terminal
R3(config)# ipv6 router ospf 1
R3(config-rtr)# router-id 3.3.3.3
R3(config-rtr)# end
! R1: send hellos toward R2 again
R1# configure terminal
R1(config)# ipv6 router ospf 1
R1(config-rtr)# no passive-interface GigabitEthernet0/0
R1(config-rtr)# end
! R2: move the link to R3 into area 0
R2# configure terminal
R2(config)# interface GigabitEthernet0/1
R2(config-if)# no ipv6 ospf 1 area 1
R2(config-if)# ipv6 ospf 1 area 0
R2(config-if)# end
R2# show ipv6 route ospf
R2# ping 2001:db8:3::3Neighbors are recalculated after every command. The transit links are point-to-point, so there is no DR or BDR on them. Both ends need the same area, neither end can be passive, and every router needs a router ID.
