It's not really a question of what makes sense, it's what you need to do to keep ARIN happy. As an ISP, if you only apply the 25% / 50% rule to your customers, how are you supposed to demonstrate 80% utilization to ARIN when requesting any kind of allocation? If you've handed out a whole bunch of /24 - /29 subnets to your customers and they are compliant with RFC2050, this could well result in a situation where you've depleted nearly all of your address space, yet are nowhere near 80% utilization or your, say, /21 from your upstream. Is ARIN going to allocate you a /20? On Sat, 16 Jun 2001, Christopher A. Woodfield wrote:
The 80% utilization rule makes sense for ADDITIONAL allocations, where an end user already has space but needs more. Of course, exceptions can be made for large deployments (customer has 150 hosts on a single /24, but needs two more for a 400-host data center, etc.)
For initial allocations, the 50% rule makes the most sense, IMHO.
-Chris
On Sat, Jun 16, 2001 at 11:10:08AM -0400, Charles Scott wrote:
On Sat, 16 Jun 2001 up@3.am wrote:
IIRC, Sprint wanted us to show 80% utilization within 3 months(!), citing ARIN guidelines...
James: That's for allocation to ISP's. The RFC refered to end user utilization of the address space (see http://www.arin.net/regserv/ip-assignment.html). I've seen some ISP's incorrectly quote the 80% utilization to customers and expect them to achieve that before assigning them more IP address space.
Chuck
-- --------------------------- Christopher A. Woodfield rekoil@semihuman.com
PGP Public Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xB887618B
James Smallacombe PlantageNet, Inc. CEO and Janitor up@3.am http://3.am =========================================================================