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I'm trying to figure out how to determine the routes acceptable by a certain AS network by reading its export/import attributes. It may work in some networks that has these headers but some other networks simpley lack this information. lets take AS11559 for instance i use the whois command:

whois -h whois.radb.net -p 43 AS11559

I get

%  No entries found for the selected source(s).

but when i use a web tool like Hurricane Electric's bgp search( found here: http://bgp.he.net/AS11559# ) i can see that in the peer list it find these:

Rank    Description     IPv6    Peer 
1   Sprint United States        AS1239
2   Verizon Business/UUnet United States        AS701

so two questions comes in mind:

  1. Why some ASN networks do not contain IRR records?
  2. How do Hurricane electric manage to retreive this data?
  3. Is there a better(and native, not scraping) way to retrieve the routing topology of an AS network?

Many thanks in advance :)

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  • Many ISPs consider their topology proprietary. Also, to which other ISPs, and how, an ISP connects is subject to change at any moment. Routing is dynamic, and the original intent of the Internet was to be able to seamlessly route around disruptions , e.g. nuclear attack. ARIN requires an ISP to jump through hoops to get an IRR record installed in its database, and some ISPs just don't bother; it's not a requirement to do this. – Ron Maupin Nov 21 '16 at 17:23
  • The IRR contains the bounding set of routes, to allow filtering of neighbours. So you can still have your routes in case of nuclear attack listed in IRR, your BGP session just isn't announcing those at this moment. The aim is to place some constraints on the dynamic routing, allowing announcements which are bogus under all circumstances to be filtered. The view of the regional routing registries towards route records varies: ARIN would prefer you used RADB, RIPE is all for them. – vk5tu Nov 22 '16 at 4:26
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Why some ASN networks do not contain IRR records

Because they don't connect with a provider which requires IRR to configure the import filters on their BGP connections.

How do Hurricane electric manage to retreive this data?

It's not the same data. IRR converts ASN to routing policy. That application just needs ASN to text, so can use the ASN allocation records at ARIN, APNIC, etc.

Is there a better (and native, not scraping) way to retrieve the routing topology of an AS network?

There is no way to discover a ISP's complete topology using any source. The bounding constraints for the exterior-visible topology may be listed in IRR. But there is no requirement to do so beyond mutual agreement of interconnecting parties (aka "convenience"). Private route databases are commonplace.

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