issue====
INFO neutron.api.v2.resource [req-79a36d02-114b-4422-b9ed-0a10c6d69451 ] update failed (client error): External network fb519e52-0f68-44c7-8d9e-a01cae24c0a6 is not reachable from subnet 05bf68d3-3bb4-4329-8c30-c7bb8ead39a0. Therefore, cannot associate Port 34a0bb99-dae9-4a15-a8af-9aaedf108899 with a Floating IP.
====
此问题是因为在创建ext-net的时候。没有在router上进行gateway设置，导致了不能将floating IP 绑定到fixed ip上
解决方案：
neutron router-gateway-set ROUTER_NAME EXTERNAL_NETWORK_NAME
问题解决。
openstack-kilo--issue(二十)External network cannot is not reachable associate Port
原文：http://www.cnblogs.com/horizonli/p/6341432.html