CIDR FAQ

Fri Aug 18 05:38:39 UTC 1995

On Fri, 18 Aug 1995, Hank Nussbacher wrote:

> >Ah. here is the rub.  When you ISP buddies come back, you should ask
> >them to return the origianal /22 for a /20.  That way, the total size
> >of the routing system stays the same!
> 
> Great idea.  Know ANYONE who does that?  The best I can do is give them a
> /20 (in addition to the original /22) if their growth warrants it.

Sure. We are starting to do that. We are trying to put into practice 
following allocation strategy:

1) when allocating, leave enough holes so the address space can be grown 
within that /16. For example, leaving next three spaces unallocated when 
assigning /24. We try to guess at who'll be growing and how much. It's 
not perfect, but it's better than nothing.

2) if the site returns /24, or /23, or /22, and we can't grow that 
address block, we try to see if we can recycle the old block and assign a 
new larger block. 

This way, if our internal routing changes, and our old aggregation scheme 
breaks, we keep renumbering to the minimum.

-dorian
______________________________________________________________________________
 Dorian Kim 		  Email: dorian at cic.net		2901 Hubbard Drive
 Network Engineer 	  Phone: (313)998-6976		Ann Arbor MI 48105
 CICNet Network Systems	  Fax:   (313)998-6105     http://www.cic.net/~dorian