How are operators using IRR?

[ML <ml () kenweb org>]

How are operators using the data available in the various IRRs?

Using an example:

AS1 is your customer
AS1 has AS2, AS3 and AS4 described as customers in an IRR
Also assume AS2 has IRR data describing AS1000 and AS2000 as it's customers.

Are operators building AS path regexes such as the following 
automatically from IRR and applying that to your BGP sessions?

----
AS1{1,}
AS1{1,} AS2{1,}
AS1{1,} AS3{1,}
AS1{1,} AS2{1,} AS1000{1,}
AS1{1,} AS2{1,} AS2000{1,}
----


I would imagine most operators that are building policy from IRR are 
building prefix lists to limit what they are accepting.  Is this being 
paired with some AS path filtering?


Are operators just traversing an AS-SET as far as it will go and 
building prefix lists to represent all intended prefixes to be heard on 
a session regardless of who originates them? Is the possibility of 
AS1000 hijacking AS2000 prefixes towards AS2 a problem you as the 
upstream to AS1 need to consider? (Last question assumes AS2 made a 
mistake and wasn't filtering properly on it's own customers and AS1 is 
just accepting all prefixes under the cone of AS2)

Thanks