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RE: IP address fee??

  • From: David Luyer
  • Date: Fri Sep 06 10:29:55 2002

> I have tended as of late to avoid using the term "class 
> A/B/C". Too many
> people at my job do not understand the meaning and make 
> themselves look
> stupid. I have instead resorted to using mask be it a /24 or a /27 aka
> "slash 27" it seems to work well with the people who have some
> experience. Other you have to train from the binary
> "11111111.1111111.11111111.00000000". But in the end the classing of
> addresses has gone the way for EGP "depricated".

I never really used the "Class C" tag because it has rarely been correct
at any place I've worked; the first place I worked, we had a class B
and used 8-bit subnets of it for departments (before the CIDR notation
became popular, the common name seemed to be 8-bit subnets); the next
place, we had a /19 CIDR block out of Class A IP space as our primary
address space (among 100 other network blocks).  In neither case would
it be correct to call a /24 a "Class C".  Although I do call 203-space
networks "Class C", because they are.

A class refers to more than just the prefix length, it refers to the
location in IP space as well.

Classful routing still causes occasional headaches, in that people who
don't configure their routers properly may accidentally be unable to
reach the whole /8 which contains our /19 (among others, of course).
Or if you use RIPv1, any IP outside your defined network statements
is automatically advertised as the classful aggregate containing that
IP (or doesn't that happen anymore?), causing horrible things to
happen (I worked at one Australian university, one of our staff
dialed up to another and specified their home static IP via PPP (IPCP),
that universities' access server automatically inserted a class B into
it's RIP and that university was doing RIPv1 with Telstra, effectively
overriding the Australian routing table -- at the time, Telstra _were_
the network -- and black-holing us as they were further east than we
were, ie, closer to the international gateway).

Although I have to shamefully admit my very small contribution to
Zebra was the classful routing assumptions for RIPv1 so we could use
it at the university I worked at (in the end it couldn't handle
interfaces dynamically appearing/disappearing so we used gated then
migrated to a hacked up routed as gated wasn't handling newer Linux
variants and I was terminating the student PPTP sessions on my
personal workstation running Linux).

David.

> On Fri, 2002-09-06 at 10:00, Joe Abley wrote:
> > 
> > On Thu, Sep 05, 2002 at 01:13:27PM -0500, Stephen Sprunk wrote:
> > > Because "Cee" is easier to pronounce than "slash 
> twenty-four".  Ease of use
> > > trumps open standards yet again :)
> > 
> > Nobody was talking. "/24" is easier to type than "class C". No
> > trumps!  Everybody loses!
> > 
> > How many people learn about networks from certification courses or
> > in school, anyway? It was always my impression that people learnt
> > mainly by listening to other people.
> > 
> > If networking on the front lines is an informal oral tradition more
> > than it is a taught science, then perhaps it's natural for obsolete
> > terminology to continue to be "taught" long after it stopped having
> > any relevance.
> > 
> > 
> > Joe
> > 
> -- 
> Manolo Hernandez - Network Administrator
> Dialtone Internet - Extremely Fast Linux Web Servers
> phone://954-581-0097  fax://954-581-7629
> mailto:manolo@dialtone.com  http://www.dialtone.com
> "The only source of knowledge is experience." - A. Einstein
> 
> 





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