change the interface name

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Deploy the instance for 4 interfaces such as eth0, eth1, eth2,eth3. But, if I shutdown the instance by using nova component (# openstack server stop <instance id="">), then, when I start the instance (# openstack server stop <instance id="">), the interface name is chenged such as eth0, eth1, eth4,eth5. [before shutdown/after restart] eth0->eth0 eth1->eth1 eth2->eth4 eth3->eth5 why this strange thig is happen???