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Re: IP address fee??

  • From: Ted Fischer
  • Date: Fri Sep 06 12:57:36 2002 
At 12:42 PM 9/6/02 -0400, you wrote:

Was this reply directed at me, particularly?


Joe
Joe,

Most definitely not. I felt that the two comments I included most closely represented the discussion and information I wanted to pass.

No offense meant, I hope none taken, apologies if they were.

Ted

On Fri, Sep 06, 2002 at 12:33:09PM -0400, Ted Fischer wrote:
> At 10:00 AM 9/6/02 -0400, Joe Abley postulated:
>
> >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
>
> The class of an address is determined by the bit-pattern of the first
> octet of the address. 10.0.0.0 will always be a Class A
> address. 172.16.0.0 will always be a Class B address, and 192.168.0.0 will
> always be Class C address. I'm not aware of any RFC that rescinded the
> definition of the Class of an address.
>
> Masks, when associated with an address, enable one to determine (a),
> what network I'm on (if I'm an IP host) or (b) how many addresses exist
> within a given range of addresses (if I'm a routing table).
>
> Subnetting (robbing mask host bits (0's) to make network bits (1's)
> allowed one to more effectively use the decreasing amounts of networks that
> required less than the default number of addresses (65,536 in the case of a
> Class B) by more effeciently using the space one had been allocated. With
> subnetting, I can take one Classful network and make many (sub)networks
> from it. There was no way prior to 1993, however, to effectively represent
> the range of addresses in more than one Classful network.
>
> CIDR, simply stated, says that one can use any address with any mask,
> regardless of the original class of the address, to represent a range of
> addresses (i.e. rob network bits to make host bits). It allows the
> properties of IP to be more effectively used for IP host addressing (only
> need a /23 to support 400 IP hosts (a very effecient 78% use of the
> allocated space), as well as (one of the original, primary reasons for
> CIDR) aggregate ("Supernet") "X" traditional Class C's into one routing
> statement (who today would advertise delivery to the range of 4,096
> addresses from, for example, 192.168.192.0 through 192.168.207.255 with 16
> individual traditional Class C statements?).
>
> Since NANOG is "the front line", then perhaps that is where the oral
> tradition should be teaching the history of IP addressing, from Classful
> addressing (default masks) to Subnetting (other than default) to
> Supernetting (ranges of addresses regardless of original - or legacy if you
> will - class (Classless)).
>
> The prefix, of course, does not refer to the class of the address, but
> the number of contiguous ones in the mask. As far as pronounciation goes,
> I prefer "slash 24" to "two fifty five dot two fifty five dot two fifty
> five dot zero" :)
>
> $.02
>
> Ted Fischer
>