Lots of prepends - AS20912 case

Tomas Caslavsky tomas at caslavsky.cz
Fri Feb 20 05:29:25 CST 2009


Hi all,

I can only cofnirm that AS47868 is using also Mikrotik as their border 
BGP router


Tomas

Giuliano Peritore wrote:
>
>         The long (176) AS20912 prepend incident was due to a 
> misconfiguration of a BGP router we were testing.
>
>         The problem is that differently to Cisco the syntax of the 
> prepend field on thius system is not a string (eg. "20912 20912 
> 20912") but an integer, that the user interface _should_ limit to the 
> interval 0-16.
>
>         Unfortunately something has gone wrong with the syntax checker 
> so you can enter a number (the number entered, thinking to Cisco 
> syntax, was 20912) and the sotware interpreted it as the request of 
> 20912 prepends... (0x51B0), dropped the highest 8 bits and processed 
> it as the request of 0xB0=176 prepends.
>
>         The producer has been warned about the problem, which I can't 
> completely define as a "bug"... but the lack of a user configuration 
> helper (syntax checker).
>
>         I think that the case of AS47868 is the same, because I seed 
> the modulo was involved too.
>
>         Many thanks to one of our upstream providers for their support.
>
>
>         ---------------------------------------------------
>         Giuliano Peritore - g.peritore at panservice.it
>         Direzione Generale - Panservice
>         Servizi professionali per Internet ed il Networking
>         Panservice e' associata AIIP -- RIPE Local Registry
>         Phone: +39 0773 410020 Fax +39 0773 470219
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>
>





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