• United States

The Network Diagram

Aug 26, 20123 mins
Cisco SystemsNetwork SwitchesRouters

aka The Crime Scene Map

Put your detective hat on your head and your Network Operational Investigator badge on your lapel.  It’s time for another entry to the Network Operational Investigating 101 subseries (NOI-101 for short).  Today we are going to talk about Network Diagrams.  Our “Crime Scene Maps”, as it were.  And if they are inaccurate… or if they are too complicated to quickly read and understand…. the direct result of that will be increased time and difficulty when troubleshooting.  And when you are troubleshooting…. TIME is not typically a luxury you can afford.  

I knew network diagrams was going to be my first post in the NOI-101 subseries.  

But I also knew that network diagrams is something I feel strongly about.  🙂   Maybe a little too strongly.  But I think that happens when you’ve watched people get burned by something time and time again and not learn… not change. 

HOW DO I GET THROUGH TO YOU?  How do I impress upon you the criticality of network diagrams that are accurate, up to date, and easy to read? 

Do I tell you war stories like the 6 hours of partial network down time because the culprit (a layer 2 switch) was not on the diagram (and, to make matters worse) did not have CDP enabled?  

Do I tell you to take ego out of your diagram and simplify it so that if you ever have to call up a support line for help you can spend time explaining your problem and not your diagram?

Do I tell you that documentation shouldn’t be an afterthought?  That the network diagram is your “crime scene map” when you are trying to figure out “who done it”?

Do I tell you that 5 9s (99.999%) means you have to less than 5 minutes of unscheduled down time in an entire year? 

Writing this Post

I have never had such difficulty writing a post as I have with this one. I’ve written this post about 10 times now.  One variation had the picture of the board of the game Clue, but with the “secret passages” between the corners missing from the board. Another variation used evacuation maps to help stress the importance of an accurate, easy to read, map. Another variation was the blueprint of a house – with every single detail of the house on one blueprint – the plumbing, the HVAC, the electricity, the carpentry, the cabinets, the placement of the furniture, etc.  Another variation was based on a couple diagrams I found on that seem to solely have been created to insure job security.  

The ideas of the varying themes didn’t seem to stop.  Anything I could think of to get the lightbulb to go on.  To get a fire under you to go and start working on your diagrams.   But then I realized something.  I was actually falling into the trap of the type of network diagram that overly complicates things.

Math Excerise for You

2 + 6 = ___

10 – 2 = ___

7 x 1 = ___

Inaccurate diagram + a problem in the network = ______________________

Complicated diagram + a problem in the network = _____________________

Stating the Obvious

Einstein was smart.

Fire is hot.

2 + 2 = 4

The network diagram is the “crime scene map” – if it is inaccurate, misleading, or hard to understand, this will have a direct relationship to your effectiveness as an Network Operational Investigator.  

Period.  Simple as that.