Just passing on my experience with ARIN and a few tips I've found to
make my life easier. I used to handle allocations for a large cable
provider, and was requesting along the lines of 1-2 /17s every three
months. Flame away if you wish, but this is what worked for me.
1) Keep records of your IP allocations and assignments (and not just
with SWIP, you need utilization numbers). I know this is a royal pain
in the rear end, and it's not always easy to do with customers. But if
you don't know how your customers are using their assigned space, you
really can't effectively plan for their future growth. They should have
to show you their projected space usage before receiving an initial
assignment. They should have to justify 80% usage to you before
receiving another assignment. In practice, I realize this isn't always
easy. But keeping records is not just for ARIN's benefit, it is for
yours as well.
I had a database that pulled the statistics per subnet. When
application time came, I put it into the pretty format that ARIN wanted
(POP - block - total IPs - used IPs - unused IPs - utilization % etc.)
and sent it in with my request. Yes, it made the size of my application
huge with two dozen POPs and scores of blocks each. Yes, it took some
time to compile, even though I was pulling from a database. But this
is the information ARIN looks at in excruciating detail. Scrimp on this,
and they will squawk. Guaranteed.
2) If you commit a 'violation', ie. one of your blocks was less than the
required utilization before assigning another, explain. If you are able
to justify, even if you simply say 'I messed up', for the most part they
will accept that. I have made mistakes in allocations, and have not
been denied additional space because of them. I just had to be very
sure I explained clearly (and up-front in the initial request !) what
the mistake was and what I was doing to fix it. In most cases, it was
simply waiting until the first allocation filled, then using the second.
3) You have to request every three months or so. I'm sorry Jeff M., but
there's really no way around this, no matter how inefficient it may
seem. Their policy is to give allocations sufficient for three months'
worth of usage, based on past growth. If your growth increases greatly,
you may need to request after two months (yes, I've done it, and I'm
sure many others have too). If you're in the midst of renumbering, and
utilization is increasing, you may have to request again after two
months, or even less. It takes time to make up the requests. It's even
more frustrating having to do it after two months instead of three. But
in the case of increased utilization, you may just have demonstrated a
need for a larger IP block. Suffer a bit, and you will eventually reap
the rewards.
Jeff, you've demonstrated that you are doing the Right Thing. Your
utilization is good and your practices seem well in-line with best
practices. ARIN will recognize this. Perhaps you don't think they do
right now, but if you were not in-line, they wouldn't have given you any
allocation at all.
4) DO NOT TRY TO BEND THEIR RULES. This should actually be Rule #1. I
made sure I put this in big, bold letters in the document I gave to my
successor. ARIN's rules are there and, unlike gravity in The Matrix,
are not meant to be broken. You can ask until your blue in the face for
six months' worth of IP space, or whatever else you like, but you won't
get it. Unfortunately this is one of those things that we all just have
to accept. They may cut you a little bit of slack to help recover from
a mistake, but that's it. Their rules are their rules. If you want to
protest them, the person who is doing your allocation isn't the right
person to protest to.
5) See Rule #4. If they give you an allocation that you don't agree
with, and they won't budge, accept it. Jeff M., I see your point that
going back to ARIN after renumbering half of the network is a tad on the
ridiculous side. Unfortunately there are times when you just have to
take your lumps and do what they want you to do. I find it unlikely
that they will deny you the second half of an allocation once you've
renumbered into the first half, demonstrated good block usage
percentage, and promised your firstborn that you'll give the original
allocation back. 
6) What Jon L. said was true. It does take a bit of practice in
dealing with ARIN and giving them exactly the information they need, in
the format they want it. Your first few dealings with them may result
in multiple clarification requests. Take it as a learning experience,
and be sure to include the information they ask for in the next request.
7) And finally.. ARIN are nice people. Really ! They're not big red
devils with flaming pitchforks just waiting to stab you in the hiney at
every chance they get. Work with them and they will work with you. I
actually started to *enjoy* my tri-montly interactions with them after a
while, if you can believe that.
Andrea Abrahamsen
Software Engineer, Intelligent Network Services
Cisco Systems
