Re: legacy /8

[Steven Bellovin <smb () cs columbia edu>]

On Apr 2, 2010, at 6:38 26PM, Andrew Gray wrote:

> Jeroen van Aart writes: 
> > Cutler James R wrote:
> > > I also just got a fresh box of popcorn.  I will sit by and wait
> > I honestly am not trying to be a troll. It's just everytime I glance over the IANA IPv4 Address Space Registry I 
> > feel rather annoyed about all those /8s that were assigned back in the day without apparently realising we might run 
> > out. It was explained to me that many companies with /8s use it for their internal network and migrating to 10/8 
> > instead is a major pain.
>
> You know, I've felt the same irritation before, but one thing I am wondering and perhaps some folks around here have 
> been around long enough to know - what was the original thinking behind doing those /8s? 
> I understand that they were A classes and assigned to large companies, etc. but was it just not believed there would 
> be more than 126(-ish) of these entities at the time?   Or was it thought we would move on to larger address space 
> before we did?  Or was it that things were just more free-flowing back in the day?  Why were A classes even created?  
> RFC 791 at least doesn't seem to provide much insight as to the 'whys'. 

Many large companies found that class A nets weren't very useful.  Multiple levels of subnetting didn't exist, which 
meant that you couldn't assign a /16 to a location and a /24 to each piece of thick yellow cable within the location, 
for example.

AT&T got 12/8 moderately early.  We realized we couldn't easily use it, and offered it back in exchange for the 
equivalent in class B space.  Postel gave us the latter (135/8), but told us to keep 12/8 -- other people were 
discovering the same problem, so there was little demand for class A networks.  (This was circa 1987, if memory serves, 
and possibly a year or two earlier.)

                --Steve Bellovin, http://www.cs.columbia.edu/~smb