27 hands-on OSPF scenarios you build in your own Cisco Modeling Labs instance and grade against the answer key. OSPF configuration and troubleshooting practice for CCNA and CCNP.
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Daily CCNA troubleshooting repair lab. Two routers share a /30 transit link and both run OSPF process 1 with explicit router-ids. IP connectivity over the transit is fine, but the OSPF adjacency never forms and remote routes are missing. Your job: work the neighbour state without changing working addressing or adding static routes. Bring the OSPF peering to FULL so the branch LAN appears on the core router.
Build a compact dual-stack enterprise topology where IPv4 is already forwarding end-to-end using OSPFv2. Your task is to bring up IPv6 routing in parallel using OSPFv3 with explicit router-ids, proving that IPv6 control/data planes operate independently from IPv4. Verify both protocols resolve separately and that an IPv4 control-plane failure does not impact IPv6 forwarding.
Advanced CCNA OSPF troubleshooting capstone on Cisco Modeling Labs (CML-Free). A three-router, two-host enterprise-style topology is pre-broken with multiple independent OSPF faults. Your job: diagnose and fix them so adjacencies form across areas and the end hosts can reach each other. The final solution forwards end-to-end and adheres to clean OSPF hygiene.
Deploy OSPFv2 across a small branch-to-edge topology, mark user-LAN interfaces passive, and originate a default route at the edge so branch hosts learn O*E2 and can reach an internet-facing host. You will implement, verify, and troubleshoot OSPF passive interfaces and default-information originate.
A compact, enterprise-clean, 5-node CML lab that builds on OSPF multi-area design. You will enable OSPF across a small core–ABR–branch topology, advertise multiple branch networks in area 10, and summarize them at the ABR using 'area range'. You will verify that specific inter-area routes are replaced by a single summary in area 0 while preserving end-to-end reachability between hosts.
Build and verify a compact, enterprise-clean multi-area OSPF network with an ABR. Configure area 0 and a non-backbone area, advertise loopbacks and LANs, enforce OSPF hygiene (passive LANs, explicit router-ids), and verify O IA inter-area routes from the endpoints.
Build a 5-node triangle OSPF topology with a branch and a data center connected by two paths: a direct link and an indirect path via a core router. Implement OSPFv2 with clean hygiene (router-ids, passive on LANs), then influence path selection by adjusting interface cost so branch-to-DC traffic prefers the core path. Verify the chosen path from the end hosts using traceroute and confirm symmetric routing by validating the reverse path.
Three IOS routers share a true broadcast multi-access segment through a Layer-2 switch. You will deploy OSPFv2, influence the DR/BDR election using interface priorities, and verify full adjacencies to the DR. An alpine client behind RTR-HQ-R3 must reach loopbacks on RTR-HQ-R1 and RTR-HQ-R2 via OSPF-learned routes. The lab emphasizes proper multi-access deployment hygiene (router-ids, passive default, interface selection) and realistic verification from the end host.
Build a two-router OSPFv2 lab, assign deterministic router-ids using loopbacks, form a clean adjacency from Down through Exchange to FULL, and verify neighbor state and router-ids. End-to-end reachability is validated from real hosts across an enterprise-clean topology.
Bring up OSPFv2 adjacency between two branch routers over a point-to-point /30, advertise each site’s user LAN and router loopback in area 0, and verify end-to-end pings succeed from the hosts. The baseline ships with addressing and SSH management ready; you will enable and tune OSPF only.
In this CCNP-level lab (BGP Fundamentals Lab 4/10), you will build a small, realistic transit-AS scenario: an external route learned by R1 via eBGP from AS 65003 must be carried across iBGP to R2 inside AS 65001. You will intentionally encounter the classic iBGP next-hop problem (R2 sees an unreachable next-hop for 172.16.30.0/24) and fix it on R1 with neighbor next-hop-self. iBGP peering runs over Loopback0 addresses with reachability provided by OSPF area 0 between R1 and R2. Two hosts validate end-to-end data-plane reachability and routing control-plane state.
Build an internal BGP (iBGP) peering between two IOS routers in the same AS over stable Loopback0 addresses, with OSPF providing loopback reachability. Each router originates a /24 from Loopback1 into BGP, and next-hop/peering behavior is validated from end hosts. This lab emphasizes the deterministic neighbor configuration (remote-as, update-source Loopback0, router-id) and exact-match network origination, supported by a minimal, secure OSPF core.
Advanced BGP capstone, run as a fault hunt. The hub lost its upstream service route overnight and the branch cannot see hub prefixes either. Sessions are not all down, which is what makes it interesting: one peering never establishes, one establishes and carries nothing, and one prefix is never originated at all. You get symptoms and the required end state — no fault list. Faults span all three routers, and one of them is not in BGP at all.
Implement classic EIGRP manual summarization on R1 to collapse four contiguous /24 loopback routes into a single /22 summary toward R2, reducing R2’s routing table entries while preserving reachability.
Hands-on CCNP OSPF lab comparing broadcast and point-to-point network types. Three routers share a multi-access Ethernet via an access switch to observe DR/BDR election, manipulate interface priorities, and then convert to point-to-point. Includes a user LAN behind R1 and realistic troubleshooting: neighbor stuck in 2-Way due to type mismatch, area mismatch isolating a router, and incorrect interface priority preventing desired DR/BDR roles.
Deploy a 5-node OSPFv2 lab featuring a redundant area 0 triangle (R1–R2–R3) and an ABR (R3) connecting to area 1 with branch networks on R4. A client on R1’s area 0 LAN validates reachability to branch loopback networks summarized by the ABR. You will set explicit router-ids from Loopback0, use passive-interface default, advertise R4’s loopbacks as /24s using ip ospf network point-to-point, and summarize area 1 into a /23 on the ABR. Verify FULL adjacencies, a single O IA summary on R1, and end-to-end connectivity. Troubleshoot an introduced area mismatch and interface/addressing issues.
Hands-on CCNA static routing and manual summarization lab using a compact HQ–Branch–Remote topology. You will replace three specific static routes to Branch networks with a single /22 summary at HQ, verify end-to-end host reachability, observe the routing table reduction, and prevent over-aggregation loops by adding a Null0 discard route at Branch. A recommended step has you add the same /22 summary at Remote (replacing its default) to practice summarization on both sides.
Deploy a compact enterprise multi-area OSPF with a backbone (area 0) and one branch area (area 10). You will configure area 10 as a stub, then transition it to a totally-stubby area from the ABR, validate reduced LSDB and routing tables, and simulate an operational fault (area mismatch) to diagnose adjacency loss and restore full transit. The lab uses three routers and two hosts to verify end-to-end reachability and real-world outcomes.
Build a 3-router triangle with two end-to-end paths between Branch A and the Data Center. Stand up OSPF area 0, create an ECMP condition, then intentionally steer traffic using ip ospf cost. Verify from the end hosts and troubleshoot common OSPF control-plane mismatches.
Build a 5-node CML lab to design OSPFv2 across two areas with an ABR that summarizes non-backbone routes using area range. Validate adjacencies, end-to-end reachability, and that the backbone learns a single summary in place of specific inter-area routes. Intentionally introduce an area mismatch, diagnose why the adjacency does not form, and repair it.
Deploy OSPFv2 with MD5 authentication on backbone links, deliberately trigger and diagnose an area mismatch adjacency failure, then fix it and restore end-to-end reachability between two branch hosts in a compact three-router topology.
Build and troubleshoot a compact multi-area OSPF design with a single ABR between area 0 and area 10. You will deploy OSPF, observe an adjacency failure caused by an area mismatch on one transit link, repair it, and validate that routes propagate end to end between two user LANs.
Deploy OSPFv2 across a 3-router, 2-LAN branch/core/edge topology. Mark LAN-facing interfaces as passive so they do not send OSPF hellos or form adjacencies. Originate a default route only from the edge router and verify default propagation end-to-end using real client traffic. Includes realistic troubleshooting around missing adjacencies, non-propagating defaults, and unreachable external destinations.
Hands-on CCNA beginner lab: build a 3-router chain with end hosts, enable OSPFv2 area 0, form full adjacencies, advertise loopbacks and LANs, verify route propagation end-to-end, and intentionally create then resolve an OSPF area mismatch on a transit segment.
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Open Shortest Path First (OSPF) is the link-state IGP at the heart of the CCNA and CCNP exams, and the protocol you're most likely to touch on day one of an enterprise networking job. Reading about LSAs, areas, and the SPF algorithm only takes you so far — OSPF clicks when you watch adjacencies form, break a neighbor relationship on purpose, and trace why a route did or didn't make it into the table.
Every OSPF lab here ships as a free-tier Cisco Modeling Labs topology you build on real Cisco IOS. You'll configure router ospf, advertise networks into the right areas, tune interface cost and reference bandwidth, and verify with show ip ospf neighbor, show ip route ospf, and show ip ospf interface. Scenarios run from a single-area adjacency between two routers up to multi-area designs with an ABR, route summarization, and stub areas — plus deliberate faults (a mismatched area, a passive interface, an MTU or timer mismatch) so you practice the troubleshooting the exam and the job actually test. Upload your export when you finish and it's graded requirement by requirement, so you find out whether your OSPF is genuinely correct, not just whether it looks right.
Yes. Each lab is a YAML package built on CML free-tier images. You import it into your own Cisco Modeling Labs instance, build it there, then upload your configuration to be graded.
Single-area adjacencies, multi-area design with an ABR, cost and reference-bandwidth tuning, route summarization, stub and totally-stubby areas, passive interfaces, default-route origination, and common break/fix faults like area, timer, and MTU mismatches.
Both. The single-area labs map to the CCNA OSPFv2 objectives; the multi-area, summarization, and troubleshooting labs go into CCNP ENARSI depth. Each lab is tagged by track so you can filter to your level.
Study the theory behind these labs — the concept explainer and step-by-step guides.
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