Hey,

New post on IGNA Online from Sarah Chen:

OSPF Troubleshooting on Cisco IOS-XE: Adjacency Failures, Flapping, and Fixes

OSPF adjacency failures are one of the most frustrating things to debug in a live network. This guide walks through the six most common causes — MTU mismatches, hello/dead timer conflicts, area type mismatches, authentication errors, duplicate Router IDs, and network type conflicts — with real show command output and fixes for each.

Also covered: how to catch flapping neighbors with an EEM script that fires before the adjacency recovers, a full troubleshooting checklist, and targeted debug usage that won't overwhelm your router.

Read the full post

— IGNA Online