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Re: Origin ASN seen vs Origin ASN in Whois Records Report?

  • From: Stephen Sprunk
  • Date: Sun Nov 23 21:17:43 2008
Joe Abley wrote:
On 19 Nov 2008, at 19:16, Heather Schiller wrote:
ARIN makes available a list of prefixes with OriginAS. I don't know if other RIR's do.

How is that list generated?

I'm not aware of any tight coupling between address assignment and AS assignment that binds anybody to advertise particular routes with particular origins, at least at the time that either is assigned/allocated by an RIR/LIR.


Presumably it's from the "Origin AS" field in WHOIS:

http://www.arin.net/registration/templates/netmod.txt

Template: ARIN-NET-MOD-4.1
**  As of February 2007
**  Detailed instructions are located below the template.

01. Registration Action (M or R): 02. IP Address and Prefix or Range:
03. Network Name:
04. Origin AS:

...

04. List all AS numbers from which the network may originate.
You can list as many AS numbers as necessary. You must separate multiple AS numbers with a comma. You may not list AS number ranges; only list individual AS numbers.


Interesting is how accurate the field actually is. Slide 6 at:

http://www.arin.net/meetings/minutes/ARIN_XXII/PDF/friday/engineering_report.pdf

says that 91% of the routes they checked had a correct Origin AS in WHOIS, compared to 64% in the ARIN IRR database.

S

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