Configure OSPFv3 for IPv6: Interface-Level Commands and Verification
Exhibit
R1#show running-config | section ipv6 ipv6 unicast-routing ! interface GigabitEthernet0/0 ipv6 address 2001:db8:1:1::1/64 no shutdown ! interface Loopback0 ipv6 address 2001:db8:1:3::1/64 ! end R2#show running-config | section ipv6 ipv6 unicast-routing ! interface GigabitEthernet0/0 ipv6 address 2001:db8:1:1::2/64 no shutdown ! interface Loopback0 ipv6 address 2001:db8:1:2::1/64 ! end
You are connected to R1 via console. Configure OSPFv3 for IPv6 on both R1 and R2 so that the loopback0 interface on R2 (IPv6 address 2001:db8:1:2::1/64) is reachable from R1. The link between R1 and R2 uses the subnet 2001:db8:1:1::/64 with R1's G0/0 having IPv6 address 2001:db8:1:1::1/64 and R2's G0/0 having 2001:db8:1:1::2/64. OSPFv3 process ID must be 100 and all interfaces must be in area 0. After configuration, verify OSPFv3 neighbors and the IPv6 route to the loopback0 network.
Quick Answer
The correct answer is to configure OSPFv3 on both routers using interface-level commands, specifically enabling OSPFv3 process 100 in area 0 on R1’s G0/0, R2’s G0/0, and R2’s loopback0, with a router-id assigned under the `ipv6 router ospf 100` process. This works because OSPFv3 for IPv6 does not use the traditional `network` statement; instead, it relies on per-interface activation via `ipv6 ospf <process-id> area <area-id>`, and the loopback must be explicitly included to advertise its prefix into the OSPF domain. On the CCNA 200-301 v2 exam, this question tests your ability to distinguish OSPFv3 configuration from OSPFv2, with a common trap being the mistaken use of the `network` command or forgetting to enable OSPF on the loopback interface. A key memory tip is: "OSPFv3 is interface-driven, not network-driven—if you want a route, enable it on that interface."
⚠ Common exam trap
Do not confuse OSPFv2 and OSPFv3 configuration. OSPFv3 uses only interface-level commands, and while setting a loopback as passive is safe, applying 'passive-interface' on a transit link will block neighbor adjacency.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0.
To achieve reachability to R2's loopback, OSPFv3 must be enabled on R1's and R2's G0/0 interfaces in area 0, and on R2's loopback0 so its prefix is advertised. Option A shows the minimal correct configuration. Option B omits enabling OSPF on loopback0, so the route to 2001:db8:1:2::/64 is not advertised. Option C incorrectly uses the 'network' command, which is not supported in OSPFv3; OSPFv3 relies on interface-level 'ipv6 ospf ... area' commands. Option D adds 'passive-interface GigabitEthernet0/0', which prevents OSPF from forming a neighbor adjacency on the link, breaking the required connectivity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0.
Why this is correct
This configuration correctly enables OSPFv3 process 100 on both routers, assigns unique router IDs, and enables OSPFv3 on the required interfaces in area 0. Including loopback0 on R2 ensures the loopback network is advertised to R1.
- ✗
On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0. No configuration on loopback0.
Why it's wrong here
This is incorrect because the loopback0 interface on R2 is not included in OSPFv3, so its route will not be advertised to R1. The loopback network must be explicitly enabled under OSPFv3.
- ✗
On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0, and also configure 'network 2001:db8:1:2::/64 area 0' under the OSPFv3 process.
Why it's wrong here
This is incorrect because OSPFv3 does not use the 'network' command under the router process; that is an OSPFv2 (IPv4) feature. OSPFv3 enables interfaces directly under the interface configuration.
- ✗
On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0, and also configure 'passive-interface GigabitEthernet0/0' under the OSPFv3 process.
Why it's wrong here
This is incorrect because while the loopback0 is included, making it a passive interface is unnecessary and does not affect route advertisement. However, the configuration is still valid but not required; the question asks for the minimal correct configuration. More importantly, the passive-interface command is not needed and might be considered extraneous, but the core error is that the configuration is not minimal. However, the question expects the exact correct steps without extra commands. The passive-interface command is not wrong per se, but it is not required and could be seen as incorrect if the question expects only necessary commands. However, the main issue is that the configuration is still correct, but the option includes an unnecessary command. To maintain strict correctness, this option is considered incorrect because it adds an unnecessary command that is not part of the standard configuration for this scenario.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0.Correct answer▾
Why this is correct
This configuration correctly enables OSPFv3 process 100 on both routers, assigns unique router IDs, and enables OSPFv3 on the required interfaces in area 0. Including loopback0 on R2 ensures the loopback network is advertised to R1.
✗On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0. No configuration on loopback0.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that loopback0 is not configured with 'ipv6 ospf 100 area 0', so its prefix is not advertised.
Why candidates choose this
Candidates might think loopback interfaces are automatically advertised, but OSPFv3 requires explicit interface-level configuration.
✗On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0, and also configure 'network 2001:db8:1:2::/64 area 0' under the OSPFv3 process.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is using the 'network' command in OSPFv3, which is invalid. OSPFv3 uses interface-level configuration only.
Why candidates choose this
Candidates familiar with OSPFv2 might mistakenly apply the 'network' command to OSPFv3, not realizing the difference.
✗On R1: ipv6 router ospf 100, router-id 1.1.1.1, interface g0/0: ipv6 ospf 100 area 0. On R2: ipv6 router ospf 100, router-id 2.2.2.2, interface g0/0: ipv6 ospf 100 area 0, interface loopback0: ipv6 ospf 100 area 0, and also configure 'passive-interface GigabitEthernet0/0' under the OSPFv3 process.Wrong answer — click to see why▾
Why this is wrong here
Using 'passive-interface' on the transit link GigabitEthernet0/0 prevents OSPF from forming an adjacency, so neighbor verification would fail.
Why candidates choose this
Candidates might think that loopback interfaces should be made passive to prevent OSPF hello packets, but this is unnecessary and not part of the required configuration.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
OSPFv3 Single-Area Configuration for IPv6
Key term
IPv6
IPv6 is the most recent version of the Internet Protocol, designed to replace IPv4 by providing a vastly larger number of unique addresses and improved network features.
Key term
Area 0
Area 0 is the backbone area in OSPF routing that connects all other OSPF areas to ensure a loop-free and efficient network routing topology.
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Same concept, more angles
1 more way this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You are connected to R1. The network must route IPv6 traffic between two directly connected routers using OSPFv3. Configure OSPFv3 on R1's GigabitEthernet0/0 interface in area 0, enable IPv6 unicast routing, and verify that R1 forms an OSPFv3 neighbor adjacency with R2 and learns the remote network 2001:DB8:CAFE:2::/64 via OSPFv3.
hard- A.Enable OSPFv3 on the interface with 'ipv6 ospf 1 area 0' under GigabitEthernet0/0.
- B.Configure 'ipv6 router ospf 1' and then 'network 2001:DB8:CAFE:1::/64 area 0' under the OSPFv3 process.
- C.Enable OSPFv3 on the interface with 'ipv6 ospf 1 area 0' under the OSPFv3 router configuration mode.
- ✓ D.Configure 'ipv6 unicast-routing' and then 'ipv6 ospf 1 area 0' under the interface.
Why D: To enable OSPFv3 and route IPv6 traffic, you must first enable IPv6 unicast routing globally using 'ipv6 unicast-routing', then enable OSPFv3 on the interface in the correct area using 'ipv6 ospf 1 area 0' under the interface. Option D provides this full configuration. Option A alone would be sufficient only if IPv6 unicast routing were already enabled, but the stem lists it as a required action.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.