Friday, May 16, 2014

I, nerd

I used to be one, Back In The Day, and it looks like my chops aren't entirely decayed.  #1 Son was reading through his Cisco CCNA training book and got stuck on subnetting.  Conceptually, he wasn't getting the mechanics.   So I sat down with him and explained the background (the why/so what/who cares), and suddenly saw the light bulb go off over his head.  Go team nerd!

Well the next day he said he didn't get route aggregation.  Oops, I thought - didn't know this, and so sat down to read his book.  Turns out I *did* now it, just that we used to call it "supernetting".  And so I explained the background/why/so what/who cares, and suddenly saw the light bulb go off over his head again.

Go team me.

Interestingly, in both cases the trick was to get him to stop thinking in decimal and to write all the addresses down in binary (seriously).  As I told him, you have to think like a router to understand why this works.

UPDATE 16 May 2014 14:28: There's a neat shortcut for calculating supernets here.  Triple propeller head stuff, but nifty.

11 comments:

ASM826 said...

11 cheers for binary!

dorfer21 said...

to ASM826 - Awesome....

To the nerdiest nerd whom ever nerded in operations operationaly (that's you Borepatch...)

Can you go over it for the rest of us who don't get it as well? I've been trying to grok this ever since i started setting up networks. I actually flunked the networking 101 cause i didn't understand subnetting. It didn't help the 'instructor' basically said 'just go do it'. Come to think of it... She wasn't really into helping the three vets in the class....

Arthur said...

I've gone through that with every base(n) numbering system I've come across. I went from 'Why the hell would anyone use this?' to 'Why the hell would anyone try to do this in decimal?' in very short order after I actually had to use it in some context.

It happened with octal too, though for the life of me I can't remember what I was doing where octal made sense to use now.

The Big Guy said...

Lovely...
Thanks- I just spent most of my morning going back through BGP configurations and case studies because your post triggered a mental note I had made to research an issue I had in Augusta a couple weeks back...
Remembered why I am a Project Manager and no longer a Network Admin...
Gah.

I'd like to know why, when I find the references in the Cisco docs to the "convenience work-arounds" that our Network Techs use, they are usually found with the phrase "Note: This change is not recommended." immediately thereafter.
Is it job security, or just Teh Stupids?

TBG

The Big Guy said...

BTW-
@ Arthur:
You do know why Engineers always confuse Halloween & Christmas?

Oct 31=Dec 25

Lissa said...

I understood precisely nothing about this post.

Except that you and #1 Son have a relationship in which he can ask you for help/explanations. That's wonderful, and not to be taken for granted :)

Borepatch said...

Oct 31=Dec 25

TBG, the Internets you just won will ship UPS 2-Day ...

Lissa, you understand what's important here. ;-)

The Big Guy said...

:-D

Thenkew! Thenkew berry much!

Dave H said...

TBG: You know the significance of the number 69, right? 69 hex is 105 decimal, and 69 decimal is 105 octal. (But you should see the funny looks I get from people when I ask that.)

Arthur: Some CPU opcodes use 3-bit fields to specify a data register or a memory addressing mode. (The Intel 8080 microprocessor, which is 40 years old this year, is like that.) It's helpful to use octal to express those codes because it's obvious which registers they're operating on. Although these days I doubt anyone has looked at an actual opcode in years.

Unknown said...

There are 10 kinds of people in the world, those who can work in binary, and those who can't.

Simon Chappell said...

Octal is used for expressing *nix file permissions (although binary is useful to figure out what you want those permissions to be in the first place).