On Monday 03 May 2010 11:25:45 Bret Clark wrote:
Uhm....okay...but why does anyone prepend their ASN that much? Are you saying the Mikrotik did that on purpose?
There was a well-known routing incident last year in which a difference between the Mikrotik and Cisco CLIs caused the propagation of extremely long AS-PATH attributes, which caused certain Cisco routers to crash. Basically, someone remembered their Cisco IOS syntax and typed "bgp-prepend 47868" into a Mikrotik; the correct syntax would have been "bgp-prepend x 47868" where x is an integer between 0 and 16 representing the desired number of prepends. The Mikrotik correctly tried to prepend 47868 47868 times, but had only one byte to store this value and therefore produced 255 prepends. Some Cisco machines, it turned out, had a bug that caused path lengths close to 255 to crash them. Fun and games ensued. The Renesys blog has much, much more: http://www.renesys.com/blog/2009/02/longer-is-not-better.shtml -- The only thing worse than e-mail disclaimers...is people who send e-mail to lists complaining about them