You can actually reproduce a similar scenario with just one vm:
> Boot instance > Associate floating ip > From within the instance, try to ping an external address (e.g. google.com)
This results in the following:
(from vm) $ ping google.com PING google.com (74.125.225.65): 56 data bytes 64 bytes from 74.125.225.65: seq=0 ttl=128 time=85.824 ms 64 bytes from 74.125.225.65: seq=0 ttl=127 time=88.867 ms (DUP!)
Doing as Evan suggests on the host machine corrects the issue:
(on host) $ sudo ip link set br100 promisc off
(from vm) $ ping google.com PING google.com (74.125.225.99): 56 data bytes 64 bytes from 74.125.225.99: seq=0 ttl=128 time=81.363 ms
You can actually reproduce a similar scenario with just one vm:
> Boot instance
> Associate floating ip
> From within the instance, try to ping an external address (e.g. google.com)
This results in the following:
(from vm)
$ ping google.com
PING google.com (74.125.225.65): 56 data bytes
64 bytes from 74.125.225.65: seq=0 ttl=128 time=85.824 ms
64 bytes from 74.125.225.65: seq=0 ttl=127 time=88.867 ms (DUP!)
Doing as Evan suggests on the host machine corrects the issue:
(on host)
$ sudo ip link set br100 promisc off
(from vm)
$ ping google.com
PING google.com (74.125.225.99): 56 data bytes
64 bytes from 74.125.225.99: seq=0 ttl=128 time=81.363 ms