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Why packets from instance cannot make into linux bridge when configure a different IP

I have done a experiment as below:

1) Create a network and make it DHCP disabled

2) Launch an instance in this network, then check its network port by 'neutron port-list', get the its info as below: | id | name | mac_address | fixed_ips | | 9dc008e0-4d98-45d7-a24f-fd5f2a7866c0 | | fa:16:3e:19:3a:2f | {"subnet_id": "6a1917b8-5fea-45ec-9937-237198cad697", "ip_address": ""} |

3) Log in the instance, and configure its IP as "", then PING "", succeeded

4) Change its IP as "", then PING "", failed

 When configure IP as  " and PING "", I tried to tcpdump -i tap9dc008e0-4d -n, I get the arp packet from instance:
 14:09:44.772154 ARP, Request who-has tell, length 28

 However,  then I try "tcpdump -i qbr9dc008e0-4d -n", didn't get the arp packets.

 It is clearly that the packets from instance didn't make into linux bridge...

So, my question is why? Is the iptables filter the packets from instance when the source IP( is not the IP( that OpenStack assigned?

If yes, is there any way to configure to allow instance to use any available IP of the network, not just the one which OpenStack assigned?