tap device down after nova reboot

[Slobodan Blatnjak]

Contrail: 2.21

Doing a (soft) reboot on the nova api will cause the tap device to be down.
Centos 7.3
Libvirt 2.0.0-10
qemu-kvm-ev-2.6.0-27.1.el7.x86_64
contrail 2.21

Another way to test without OpenStack api:
virsh shutdown $instance
virsh start $instance

On a centos 7.2 hypervisor this will put the tap device in an up state.
However with centos7.3 the device will keep in a down state.
Not sure this is a contrail or libvirt/qemu bug.

For now they "fixed" it in the nova code by making it do a hard reboot after the shutdown which will put it back in a good state.
However it would be nice to make it work again with default upstream code.

[Slobodan Blatnjak (sblatnjak)]

The tap interface is down during a softreboot whereas it is up during an hardreboot.

Contrail 3.2.3
Red Hat 7.3
Libvirt version 2.0.0 release 10.el7_3.9
qemu version 1.5.3 release 126.el7_3.10

1. src_mac address of the VM
### ifconfig -a
eth0 Link encap:Ethernet HWaddr 02:B7:A8:71:AA:14

2. tap interface name of the VM
tapb7a871aa-14 (compute0)

3. tcpdump from tap interface of the VM2 (with softreboot and hardreboot)

###softreboot: openstack server reboot --soft test_power_management
#results on the compute node:
[nie@pop199a-compute0 ~]$ sudo tcpdump -n -i tapb7a871aa-14
tcpdump: tapb7a871aa-14: That device is not up