A heavily flapping AS struck my curiosity: AS 10916. Somehow, AS 6138 constantly appears and disappears out of the path leading through AS 1239 - the other path to them via AS 701 is barely flapping at all. # sh ip bgp regexp 10916 [...] Network Next Hop Metric LocPrf Weight Path *d 63.87.96.0/24 censored 95 110 0 13789 1239 10916 i *> censored 98 100 0 701 10916 i [...] And every few minutes: *d 63.87.96.0/24 censored 95 110 0 13789 1239 6138 10916 i *> censored 98 100 0 701 10916 i [...] What could be the cause for an AS appearing/disappearing in a path every few minutes? Is it really AS 6138 that is flapping for 10916? For some reason they prefer the indirect route through 6138 to 1239 (SprintLink), instead of their direct connection to 1239. These are the times when such a peer should be shut down for the sanity of the rest of the network. bye,Kai