Observed arrival · 2026-09-11

Adjacency Labs: Network Troubleshooting by Controlled Failure

adjacencylabs.dev Observed source

Editorial interest 82/100 Selection signal · not a rating of the site

A pack of ten Containerlab exercises that deliberately break OSPF and BGP scenarios, then asks learners to diagnose the mechanism before revealing the fix.

Landing page captured for the 2026-09-11 issue.

Field notes

The exercises ship as topology files, per-router startup configurations, and scenario documents for Containerlab with FRR. The public sample uses three nodes across two OSPF areas and asks learners to explain why three /24 routes were not summarized into the expected 10.3.0.0/22 route. The broader pack divides ten scenarios evenly between OSPF and BGP, covering failures such as MTU-related EXSTART, route-reflector omission, unreachable next hops, and ineffective AS-path prepending.

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✦PrettyNotable craft visible

●ProPolished or operationally mature

◎NicheUnusually specific use

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