Multiple discontiguous copies of an AS number in the AS-path can also be caused by the "original" Cisco IOS "local-as" feature, but in that case the AS number in the middle would be fixed. http://bit.ly/7TnCi And there's always the AS-path prepending. Cisco IOS allows you to insert anything in the AS path. Ivan http://www.ioshints.info/about http://blog.ioshints.info/
-----Original Message----- From: yangyang. wang [mailto:wyystar@gmail.com] Sent: Sunday, May 10, 2009 12:52 PM To: nanog@nanog.org Subject: ASPATH Loop
Hi， NANOG：
When I was analyzing the BGP RIB data from RouteViews, I found that there were aspath loop in many bgp rib entries. For example, in the file rib.wide.20090301.0319, the peer 202.249.2.169 in AS2497 observed the following aspaths:
3130 29283 3130 2914 2497 3130 7337 3130 2914 2497