New IPv4 Allocation to ARIN

Richard A Steenbergen ras at e-gerbil.net
Mon Jan 19 18:39:18 UTC 2004


On Mon, Jan 19, 2004 at 10:22:08AM -0800, william at elan.net wrote:
> 
> Also as you know I have been running statistics at 
> http://www.completewhois.com/statistics/
> (note: dont believe about "green" for 70/8, I still have not fixed collection
> to ignore occasional single wrong announcements from routeviews)
> 
> Its interesting that 69/8 block is currently only 39% allocated. To be 
> honest I was not expecting ARIN to request another block under such 
> condition, I was expecting when its either almost full (say 75%) or when 
> it reaches previously agreed upon mark of 50% (see my other post). 
> The only thing I could think of is that ARIN is allocating smaller block 
> leaving some portion of the block "in reserve" for future allocation to 
> the same entity and as a result it reached "critical point" of beyond 50
> percent point of the block. So I checked and found that 69.128.0.0/18 was 
> actually allocated on 2003-03-25. Checking again, it turns out the last
> (in terms of beginning) allocation they have is 69.178.0.0/17 made on 
> 2004-01-13. Ok so 0-178 makes it 70% used for that class-a as far as 
> point they reached for allocations. 

Yes, ARIN typically leaves at least 100% (or more depending on growth
patterns) of the initial allocation as unallocated space, left in reserve
for future growth. If the user comes back for more IP space, they just
expand into that unallocated space, without the need to create
non-connected allocations which can't be aggregated. Eventually if you
don't come back and claim your space, it is given away to someone else
(btw I'd love to know the timelines for that).

The 39% number makes a lot of sense given the 70% usage measured "in
sequential order". I'm sure that the number of people who have come back
for space is slightly higher than 4%, and is offset by some larger
reservations (ex: the people who are on their 2nd or 3rd allocation, who
have already been through a /19 or /18, and who are reserved a /16 even
though they only eat new blocks a /19 at a time), but it's a good rough 
estimate.

One point I would make is that ARIN certainly gives itself a luxury that
its users do not have when it comes to reserving IP space for the future
growth of its customers. The only option providers have to reserve space
for their customers and still continue to get new IP space under the 80%
utilization rules is to SWIP their customers a larger block than they
need, and then explain it to ARIN when they ask how that customer
justified said block (and there are still plenty of hostmasters who will
argue with you about it :P). This is easier to do for end users because of
their lower utilization requirements, but more of a pain for reallocations
to people who will reallocate themselves. Also, it doesn't have quite the
same effect for keeping customers in line when you hand them a SWIP for 2x
what they asked for and say "try to use this efficiently, and keep the 2nd
half reserved for your future growth" instead of being able to portion it
out to them. I would rank this problem as one of the larger contributors
to the /24 announcements on the global routing table, as customers with a 
steady growth pattern who don't want to pay ARIN a few thousand dollars 
for direct IP space keep coming back for space which their providers can't 
hold in reserve and still keep ARIN happy.

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)



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