OSPF cost and the traffic taking the wrong path
Traffic prefers a slow link over a fast one. The cause is usually a default reference bandwidth.
Writing
Articles
OSPF areas and why the design matters
Areas are not organisational tidiness. They control how much work every router has to do.
Interface counters and what they actually tell you
Every error counter has a specific meaning. Knowing which is which turns guessing into diagnosis.
Cable faults that look like software faults
Hours get spent in configuration for problems that live in the first metre of the path.
Three questions before touching a production network
Not process for its own sake. Three questions that have prevented more outages than any tool.
Jumbo frames: worth it, or not
They help in specific places and cause silent breakage everywhere else. Decide deliberately.
Broadcast domains and why they still matter
Switching is cheap, so people build large flat networks. Here is what that costs you.
When traceroute lies
Asterisks are not failures and high latency at hop four is usually nothing. Read it correctly.
TTL as a diagnostic instrument
The time-to-live field quietly tells you how many hops a packet took. That is more useful than it sounds.
Reading a packet capture without drowning
A capture with two million frames is not evidence until you have reduced it. Here is the order that works.