OSPF Lab Documentation

In this project, I built a multi-area OSPF lab to simulate how large enterprise networks manage routing. The goal was to go beyond a simple single-area setup and explore real design challenges such as:

connecting non-backbone areas with a virtual link,

reducing routes using summarization,

blocking external LSA with stub area configs, and

exchanging routes between OSPF and EIGRP through redistribution.

Each section highlights the problem, the configuration applied, and the routing changes before and after implementation.

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1. Topology Overview

• Multi-area OSPF (Areas 0, 1, 2, 60)
• EIGRP domain connected via R4
• ISP cloud for external reachability
• Loopbacks simulate end-user subnets

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2. Virtual Link

Purpose

Area 2 was not directly connected to Area 0. A virtual link was configured through Area 1 to maintain backbone connectivity.

Before

R1

R4

• OSPF adjacency between R2 and R3 not fully established
• Backbone reachability broken on R4

After

R1

R4

• Virtual link established
• Backbone adjacency restored (FULL state)
• Routes from Area 0 successfully learned in Area 2

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3. Stub Area (Area 60)

Purpose

Reduce LSDB size in Area 60 by blocking external and inter-area routes, injecting only a default route.

Before

• Area 60 received the full routing table, including external prefixes

After

• Area 60 receives only a default route (O*IA 0.0.0.0/0)
• External routes filtered
• Smaller, optimized routing table

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4. Redistribution (OSPF ↔ EIGRP)

Purpose

Allow OSPF domain to reach networks in EIGRP, and vice versa, using R4 as the redistribution point.

Before (Redistribution OFF)

• No external routes (O E2) in the OSPF domain
• OSPF-only routers could not reach EIGRP networks

After (Redistribution ON)

• External routes appear as O E2
• OSPF domain can now reach EIGRP networks
• Verified with successful pings

Action Reference


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5. Verification Commands

Key commands used:

show ip route
show ip ospf neighbor
show ip ospf database
show ip protocol
show running-config | section ospf
show ip ospf interface
traceroute [destination]
ping [destination]

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## 6. Lab Download & Import

The full EVE-NG lab (with configs) is included in this repo.

- Download: [multi-area-ospf-lab.zip](lab-files/multi-area-ospf-lab.zip)

### Import via EVE-NG GUI
1. On your EVE-NG web interface at the Lab list page, click **Import** at the top.  
2. Select the downloaded `multi-area-ospf-lab.zip` file and click upload.  
3. The lab will appear in your list, open it and start the nodes.  

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## 7. Known Caveats
- On reload, some nodes show **duplex mismatch** messages due to emulation quirks; routing is unaffected.