PlantUML DiagramOSPFv3 Address Family Configuration
A structured lesson workspace with readable content, hands-on examples, and a clean path to completion.
! Enable IPv6 routing globallyR1(config)# ipv6 unicast-routing! Modern approach — OSPFv3 under address family (IOS 15.2+)R1(config)# router ospfv3 1R1(config-router)# router-id 10.255.255.1R1(config-router)# exit! Enable OSPFv3 on interfacesR1(config)# interface gigabitEthernet0/0R1(config-if)# ospfv3 1 ipv6 area 0R1(config-if)# exitR1(config)# interface loopback0R1(config-if)# ipv6 address 2001:db8::1/128R1(config-if)# ospfv3 1 ipv6 area 0R1(config-if)# exit! VerifyR1# show ospfv3 neighborR1# show ipv6 route ospf
OSPFv3 is a separate protocol from OSPFv2 — it doesn't just carry IPv6 over OSPFv2. It uses the same algorithm but a fresh packet format, different LSA types, and gets its next-hop information from link-local addresses instead of IPv4 addresses. In IOS-XE, OSPFv3 is often configured alongside OSPFv2 using address families for unified management.
| Aspect | OSPFv2 | OSPFv3 |
|---|---|---|
| Runs over | IPv4 (protocol 89) | IPv6 (next-header 89) |
| Neighbor next-hop | Interface IPv4 address | Link-local IPv6 address |
| Router ID | 32-bit, from IPv4 IP | 32-bit, still looks like IPv4 (RID format preserved) |
| Authentication | Built into the packet | Uses IPsec (AH/ESP) or RFC 7166 auth trailer |
| LSA types | Type 1, 2, 3, 4, 5, 7 | Type 1, 2, 3, 4, 5, 7, plus new types |
| Multicast address | 224.0.0.5 / 224.0.0.6 | FF02::5 / FF02::6 |
| Per-link processing | No | Yes — multiple instances per link |
The Router ID is still written as an IPv4-looking address in OSPFv3. This trips people up — the RID has nothing to do with IPv4 addressing. It's just a 32-bit number that OSPF uses as an identifier. Convention is to use a loopback IPv4 as the RID even in IPv6-only networks.
The output is similar to OSPFv2 but shows `OSPFv3 1 address-family ipv6` at the top. Neighbor IDs are the 32-bit Router IDs, not IPv6 addresses. The interface ID column is unique to OSPFv3 — it identifies the interface for the LSA exchange instead of using an IP address.
The address family model simplifies dual-stack deployments. One OSPFv3 process manages both IPv4 and IPv6 routing under address families. You don't need separate OSPF processes for each protocol.
You're migrating a dual-stack network from OSPFv2 for IPv4 and static routes for IPv6 to a unified OSPFv3 configuration that handles both. What's the migration approach?
Select the safest next action.
Section 12 complete. You understand dynamic routing protocols, OSPF architecture, neighbors and adjacencies, Router IDs and network types, cost calculation, configuration, troubleshooting, and IPv6 support. Section 13 covers IP services — DHCP, DNS, NAT, NTP, syslog, and SNMP.
Finish the lesson once you have worked through the material. This awards ★ 40 XP.