Common operational misconceptions

George Bonser gbonser at
Sat Feb 18 20:36:50 UTC 2012

> Yes I'm serious, they were CCNP qualified, hired as a NOC engineer for
> an ISP & Hosting company.  

There was a time a new hire with all the right holes punched in his ticket deleted an item in an access-list in a PIX that was running an older version of the software than he was familiar with.  The entire access-list disappeared and he was locked out, production stopped, like a train hitting a brick wall.  

> For the company the NOC team was the top
> tier of customer support (3rd line+), they looked after routers,
> switches, firewalls, servers, leased lines, and so on.
> This individual was perfectly capable of regurgitating all the facts,
> figures and technical details you can imagine, probably pretty much the
> entire CCNP syllabus.  What they didn't seem that capable of was
> actually applying that to anything.

You might be surprised at how common that is.  If you present them with ALL the diagrams and ALL of the configs on paper, they can figure it out.  In other words, if you recreate the same environment they had in their training class, they can do fine.  But what some can't seem to be able to do is visualize in their head how things are.  It is that layer of abstraction that separates them out.  They are fine for maintaining documentation or even for participating in a design review but you don't want them designing some new addition to the network or working on something "live".  My first clue often comes from the quality of diagrams they produce. If the diagrams are accurate as far as what connects to what but do not reflect the actual flow of the network, that's a telltale sign.  Sort of like an electronic schematic.  If they sort of have random components/stages at random locations in the drawing that doesn't really reflect the functional flow through the device, that is my clue that I am likely dealing with a concrete thinker and not an abstract thinker.  Ditto if they demand that the symbol representing a particular piece of gear actually be a picture of that piece of gear.  If they get lost when gear is represented by a square box then they are probably part of the normal 85% of people who find it more difficult (actually have to try) to translate a square box on a diagram to a router in the rack in their head vs the 15% who do that naturally without any effort.

The access-list guy mentioned above would be great for looking at the config and producing a new one with the correct access control, but you wouldn't want him to be the one to apply it in production on a live network.  So even in that guy's case, there is a place where their skills can be quite useful and there are other places where their chance of making a costly mistake increase.  It is a matter of matching the person's role to their skills.

> I'd bet good money that if I'd
> asked him at the time what the 1918 network ranges are he'd have been
> able to tell me.

You'll be surprised how many people "forget" that is rfc1918 space.  They are so used to seeing 172.16 that they tend to forget 172.17-31. I've had to change null routes and access controls to include the entire /12.  They "know" that it is a /12 but seem to forget in practice when they see a second octet that isn't "16".

> This is exactly what we're teaching kids to do these days (makes me
> feel so old that I've already been saying this for several years and
> I'm only
> 31) standardised tests aren't marked based on ability to apply
> knowledge, just the knowledge itself. 

Yes.  We teach them facts but now how to FIND facts.  Part of teaching is in teaching how to teach yourself.  It started with me when I was a kid.  When I had a question, my father would always say "look it up and tell me" even if he knew the answer perfectly well.  He had invested in an encyclopedia and the annual updates and was determined that I would use it.  It taught me how to research to find my own answers and it taught me to learn it well enough to explain it to someone else because Pop would always throw in a couple of questions for me after I explained it to him just to see if I actually "got" the underlying concept.  Besides, often in the course of researching one thing, I happened across a completely unrelated thing that caught my interest in that volume of the book and learned something I hadn't even been looking for.  Forget the Internet, for people with kids at home, I would recommend a hard copy set of World Book with the Year Book and Science Year annual additions.  That one in particular because the style in which they are written, they are actually pretty fun to read and have a lot of illustrations. (no affiliation at all with them, just a satisfied "customer").  Soon, going to the books when a question arose became natural.

It is one thing to produce a "teachable" child, something quite different to produce the ability to learn independently and allow their own natural curiosity to "pull" them to that knowledge.

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