ISP customer assignments

John Kristoff jtk at cymru.com
Tue Oct 13 14:21:46 UTC 2009


On Tue, 13 Oct 2009 08:14:59 -0400
Joe Abley <jabley at hopcount.ca> wrote:

> > While I may agree that teaching classful routing is stupid, the
> > addressing part lets people start getting the concept of binary.
> 
> That's true of classless addressing, too. When students have
> problems with non-octet bit boundaries, that just means you start
[...]
> You were suggesting that classful addressing is reasonable to teach  
> because it's simpler. It's not simpler, and in a modern-day context  
> it's just wrong.

I occasionally teach college level courses in networking, typically
undergrads or grad students at DePaul University.  I think I can offer
some perspective from both the academic and operator viewpoint.

No matter the class or the student, I always have to spend at least a
week on IP addressing, even to students who should be coming in with
already having had it, sometimes in multiple previous classes. Some
know it fairly well, but with holes mostly due to lack of practical
experience.  I don't think I've seen anyone who would be considered
expert enough to withstand the scrutiny of this crowd (though that
probably goes for just about anyone really :-).

No question about it, but something more than basic classful addressing
for students who don't typically have to do it on a regular basis is
not easy.  Those who aren't afraid of math, can grasp numbering systems
and binary arithmetic usually fare better.

Some instructors are most certainly doing some harm.  From what I can
tell, classful addressing is always taught and if classless is taught,
its practical reality and importance is not always stressed.  In my most
recent class this semester I made it abundantly clear to my students
that classful addressing, while interesting and useful to know from a
historic perspective, is obsolete and deprecated.  A student who has
another networking related class with another instructor came back
saying their other instructor disagrees. :/

John




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