UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

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Computer Networks II

OSPF Routing

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

Supervisor: Rania Garofalaki, Laboratory Teaching Staff

UNIWA Profile · LinkedIn

Athens, May 2022

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Project Overview

The primary objective of this project was to establish full IP connectivity within Autonomous System (AS) 20 using the OSPF routing protocol.
The network architecture was designed using multiple OSPF areas:

• Area 0 (Backbone Area)
• Area 10
• Area 20

These areas are interconnected through Area Border Routers (ABRs), ensuring proper inter-area routing and adherence to OSPF hierarchical design principles.

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Table of Contents

Section	Folder / File	Description
1	assign/	Assignment material
1.1	assign/OSPF - homework_NetworksII.pdf	Assignment description in English
1.2	assign/OSPF - homework_ΔίκτυαΙΙ.pdf	Assignment description in Greek
2	docs/	Project documentation
2.1	docs/OSPF_Routing.pdf	OSPF routing analysis and configuration (English)
2.2	docs/OSPF_Δρομολόγηση.pdf	OSPF routing analysis and configuration (Greek)
3	src/	Source files
3.1	src/OSPF.pkt	Cisco Packet Tracer topology and OSPF configuration
4	README.md	Repository overview and usage instructions

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Network Configuration Details

1. OSPF Process Configuration

OSPF was configured on each router by defining:

• A process ID
• A unique Router ID
• The participating subnets and their corresponding OSPF areas

Router IDs Used

• R1: 1.1.1.1
• ABR2: 2.2.2.2
• ABR3: 3.3.3.3
• R4: 4.4.4.4
• R5: 5.5.5.5

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2. Implementation Steps

The following Cisco IOS CLI commands were used during router configuration:

• router ospf <process-id>
  Initiates the OSPF routing process.

• router-id <address>
  Assigns a unique identifier to the router.

• network <ip-address> <wildcard-mask> area <area-id>
  Specifies which interfaces and subnets participate in OSPF and assigns them to the appropriate area.

• passive-interface <interface>
  Configured on R4 and R5 (interface FastEthernet0/1) to prevent the transmission of OSPF updates toward non-router end devices.

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3. Route Summarization

To improve routing efficiency and reduce the size of routing tables, inter-area route summarization was implemented on the ABRs.

Summarized Routes

• Area 10 Summary:
  172.16.32.0/23
  (Summarizes 172.16.32.0/24 and 172.16.33.0/24)

• Area 20 Summary:
  174.18.30.0/23
  (Summarizes 174.18.30.0/24 and 174.18.31.0/24)

• Area 0 Summary:
  173.17.36.0/22
  (Summarizes 173.17.37.0/24, 173.17.38.0/24, and 173.17.39.0/24)

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Verification Commands

The following commands were used to verify the correct operation of OSPF:

• show running-config
  Confirms the applied OSPF configuration.

• show ip route
  Displays the routing table and verifies inter-area (O IA) routes.

• show ip ospf neighbor
  Examines OSPF neighbor relationships and adjacency states (e.g., FULL/DR, FULL/BDR).

• show ip ospf database
  Inspects the Link State Database (LSDB) and the different LSA types.

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Installation & Setup Guide

This project is implemented using Cisco Packet Tracer and demonstrates multi-area OSPF routing.
No compilation or programming environment is required.

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Prerequisites

Software

• Cisco Packet Tracer (version 7.3 or newer recommended)
  • Must support:
    • OSPF routing
    • Multi-area OSPF
    • Route summarization
• Operating System
  • Windows 10 / 11
  • Linux
  • macOS

Cisco Packet Tracer is available for free to students via Cisco Networking Academy (NetAcad).

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Installation

1. Clone the Repository

git clone https://github.com/Computer-Networks-2/OSPF.git

Alternatively, download the repository as a ZIP file and extract it locally.

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Project Structure

After cloning or extracting the repository, the relevant file is located at:

src/OSPF.pkt

This file contains:

• The complete network topology
• Router interface configurations
• OSPF processes and area assignments
• Route summarization on Area Border Routers (ABRs)

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Setup Instructions

Open the Project in Cisco Packet Tracer

1. Launch Cisco Packet Tracer
2. Select File → Open
3. Navigate to:

src/OSPF.pkt

4. Open the file and wait for the topology to fully load

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Verify Router Configuration

To inspect or validate the OSPF configuration:

1. Click on any router (R1, ABR2, ABR3, R4, R5)
2. Open the CLI tab
3. Execute the following commands:

show running-config
show ip ospf
show ip ospf neighbor
show ip route

These commands verify:

• OSPF process activation
• Router IDs
• Neighbor adjacencies
• Inter-area routing entries (O IA)

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Testing & Validation

Connectivity Testing

• Use Ping between hosts in different OSPF areas
• Confirm full IP connectivity across:
  • Area 0 (Backbone)
  • Area 10
  • Area 20

Routing Validation

• Ensure routes are learned dynamically via OSPF
• Verify summarized routes appear on ABRs
• Confirm that no unnecessary specific routes propagate between areas

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Troubleshooting

OSPF neighbors not forming

• Check interface status (up/up)
• Verify correct area IDs
• Confirm matching subnet masks and wildcard masks

Missing routes

• Verify OSPF network statements
• Check summarization configuration on ABRs

End devices receiving OSPF updates

• Ensure passive-interface is configured on access-facing interfaces

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Open the Documentation

1. Navigate to the docs/ directory
2. Open the report corresponding to your preferred language:
   • English: OSPF_Routing.pdf
   • Greek: OSPF_Δρομολόγηση.pdf