Re: First draft of the European Template for IP number requests

[Marten Terpstra <]

 Havard.Eidnes@localhost writes:
  * > > 	 Format: quantity of numbers requested followed by class of req
  * uest.
  * > > 
  * > > 	 Example - req-typ:  1 class C
  * > > 
  * > > 	 In making the application, please be guided by the following 
  * > > 	 EXAMPLES of number of hosts which relate to the quantity of 
  * > >          network numbers requested:
  * > > 
  * > > 	  1 class C number (up to 255 hosts)
  * > > 	  2 class C numbers (up to 510 hosts) 	
  * > > 	  4 class C numbers (up to 1020 hosts)
  * > > 	  8 class C numbers (up to 2040 hosts)
  * > > 	 16 class C numbers (up to 4080 hosts)
  * > > 	 32 class C numbers (up to 8160 hosts)
  * 
  * I have for a while looked at these host numbers as somewhat inaccurate,
  * primarily since this does not take subnetting into account.  If you subnet
  * a class C network number (as some people end up doing, as was mentioned by
  * Peter Koch, since sometimes people have a small number of hosts at a given
  * site), you *always* waste address space, since subnet 0 and -1 and host 0
  * and -1 can (normally) not be used.  Thus, the best utilization one can make
  * of a subnetted class C network number is around 75% (if I haven't made an
  * error in my calculation).  If there is a need for two large subnets, the
  * largest potential utilization immediately drops to around 50%.

Not quite sure what you mean here. What do you consider the best utilization
of a subnetted class C address ? If you split up the C net in 32 hosts parts
(actually 31), you loose hostnumbers 0,32,64,96,128,160,192,224 and 255
(which is 9 hostsnumbers out of 255 ~ 3.5%). With two large subnets you loose
hostnumbers 0,128 and 255 which is around 1%. The only thing is that you will
have to convince people to pack their network numbers as good as possible.

  * It is good to see that the number of subnets is asked for.

Exactly, and I think that the mix of number of hosts and subnets is a good
indication for the registries to base the assigments on. I do not think that
one should simply give whatever they ask for. We have had more than one case
where people had 1500 hosts on 50 subnets and asked for 50 class Cs. You
really want these people to only use up 8 or maybe 16 Cs. Besides if you
compare the hosts and subnet predictions together with the number of nets
they request, you get a fair idea whether of not they have any idea what they
are doing ;-)

-Marten