In this series of troubleshooting tickets, we will find and fix problems with the OSPF adjacency between routers.

At the end of the lesson, you can download the EVE-NG file and try to troubleshoot the ticket yourself. Then, you can review the lesson and see if you used the same approach.

Ticket Topology

For this ticket, we are going to use the following initial topology, highlighting the issues that we are going to troubleshoot.

All devices run OSPF in Area 0 and must establish adjacency with their neighboring routers.

Ticket Issues

Suppose you are a network engineer supporting a big enterprise company. You have received a ticket with the following two reported issues, which are highlighted in the diagram above:

• Issue #1 - R4 cannot form OSPF adjacency with R6.
• Issue #2 - R4 cannot reach network 10.48.1.0/24 at the small branch.

You are given the "cisco/cisco" credentials. However, you cannot use the show run command for company security reasons. Therefore, you must resolve the issues without looking at the routers' configurations.

Troubleshooting Workflow

Let's troubleshoot both issues using the approach we used in the previous ticket.

Issue #1

The issue is reported as "R4 cannot form OSPF adjacency with R6". First, let's verify that the routers are not neighbors indeed.