troubleshooting

• Russ's course on OE
• dwell time - time to detect the failure
• resilience doesn't equal redundancy
• failure domain - set of subsystems impacted by a failure in other subsystem
• aggregation - abstracting reachability info
• summarization - abstracting topology info
• contrary to the popular belief - tend to larger failure domains - ?
• be conservative in continuous observation (extensive measuring can change the way the network works [or doesn't]), be liberal in instrumenting to measure (have the possibility to measure more)
• know what normal looks like
• 2 am rule - if you cant explain the config at 2 am to a non native speaker, you shouldn't configure it (unless no other solution exists)
• LOC = Loss Of Carrier
• if you haven't found the trade-off, you haven't looked hard enough
• what changed last; what can be checked quickly; measure and half split
• show commands, logs, debugs, pcaps