fgts don't know 'bout my BGP Traffic-Engineering
I peer with AS4134. I prefer his China routes because they are directly connected. So, I set BGP LOCAL-PREF on them over all other points where I might see them. I am ATT peering co-ordinator (except I am not in this case).
In the meantime, China Telecom, AS4134, just like any other provider are also peering with facebook and taking AIDS in at all IXPs. They make a change to their peering prefix-list/ communities/ as-path regular expressions and - suddenly AIDS is announced via China to ATT. ATT now has the AIDS and forwards traffic in that direction.
It's a simple configuration step for the BGP Peering co-ordinator in AS4134 to get his config wrong and release the AIDS toward ATT.
And so traffic flows toward AIDSBook exiting the ATT autonomous system via China Telecom because ATT Policy says so.
It's a problem in China that can be used to exploit traffic flows but it is open to any ISP that does not filter properly. The internet is stuck together with glue and tape.
Behind AS4134 there is a very powerful network but this is nothing more than a BGP Traffic-Engineering issue that goes on daily.