1. How routers become neighbours
Before OSPF shares routes, two routers must agree to become neighbours. They introduce themselves with Hello packets, then swap their map of the network (the LSDB). Change R2's settings and press Next step.
Down
Down
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2. OSPF cost
Each link gets a cost: reference bandwidth ÷ link bandwidth (minimum 1, rounded down). Lower cost is better. A path's cost is the sum of its links.
Which path wins?
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3. Shortest path first
Every router runs Dijkstra's algorithm on its map to find the cheapest path to each network. Click a link to select it, then change its cost. Thick green = path to your destination; blue = the rest of the shortest-path tree.
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Use the default costs (press Reset costs first).
4. Convergence after a failure
Click a link or router to break it. Notice the old route still points at the broken part until OSPF converges. Then press Converge and watch the LSAs flood.
LSDB (Router LSAs, with sequence numbers):
Route table from R-A to R-F is shown below.
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5. Final challenge
Your result
Finish every question to see your result.