[arin-ppml] ARIN 2-Byte ASN inventory and issuance (was: Re: 2-byte ASN policy)

John Curran jcurran at arin.net
Thu Apr 7 14:44:05 EDT 2016

Folks -

Please forgive this omnibus email of information, but we've had sufficient individual 
questions for 2-byte ASN data that it simply made more sense to provide one full 
summary rather than reply to each question individually...

ARIN continues to have classic, 2-byte, AS numbers in inventory. Over the last few
years, we have received small blocks of them in our new delegations from the IANA, 
obtained them from customer returns of AS numbers, or through revocations of AS 
numbers due to non-payment of registration fees.

Our last AS block delegation from IANA was on 29 April 2015.  We received 99 2-byte 
ASNs and 925 4-byte ASNs at that time, and do not expect to receive any additional 
2-byte ASNs from the IANA in future delegations.  The 2-byte ASNs received from the 
IANA in 2015 were added to the inventory and placed on hold.  The reason that the 
2-byte ASNs were put on hold is that was not responsible to issue from the dwindling 
quantity of these resources to parties that did not specifically request such while we 
were still receiving AS number requests specifically asking for 2-byte AS numbers. 

As of today, we currently have the following 2-byte ASNs in ARIN inventory:

       387 2-byte AS numbers on hold (most were routed at some point)
       535 2-byte AS numbers revoked
       133 2-byte AS numbers returned

  = 1,055 2-byte AS numbers returned/revoked/held (Total)

Customers requesting ASNs receive a 4-byte ASN by default.  If a request comes in 
that specifically requests a 2-byte ASN, we inform the customer that we have noted 
their special request and that we will accommodate it at the issuance phase of the 
ticket process if we have 2-byte ASN available at that time. 

Rate of issuance for 2-byte ASNs per month -

    1/2015: 68
    2/2015: 77
    3/2015: 74
    4/2015: 60
    5/2015: 7
    6/2015: 12
    7/2015: 16
    8/2015: 4
    9/2015: 7
    10/2015: 11
    11/2015: 7
    12/2015: 11
    1/2016: 5
    2/2016: 6
    3/2016: 13

A waiting list will only be applicable after depletion of the present 2-byte ASN inventory, 
hence the following general run-out estimates are provided for consideration:           

   - If we release all of the 2-byte ASNs from hold and issue ASNs strictly from smallest
     to largest, i.e. the practice prior to May 2015, it is likely that the current inventory of 
     2-byte ASN’s would last somewhere between 6 to 12 months.

  -  If we continue the current approach (wherein 4-byte ASNs are issued by default and
     2-byte ASNs are only issued upon special request), the current inventory of 2-byte 
     ASNs would appear to last for many years (5+ years at present rate).

I hope the above information helps in your policy development efforts!

Thank you,

John Curran
President and CEO
American Registry for Internet Numbers (ARIN)

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