Comment 0 for bug 1576168

Detailed bug description:
I found a lot of ERROR logs for Ceilometer that it cannot obtain IP address of instance:

2016-04-28 09:03:06.254 14501 ERROR ceilometer.hardware.discovery [req-fc590e4d-3e11-48d3-98f7-ee94af3c43ec admin - - - -] Couldn't obtain IP address of instance 5a4c7651-7d3e-4bab-b8ee-fdda9be15703
...
2016-04-28 09:42:55.889 14501 ERROR ceilometer.hardware.discovery [req-fc590e4d-3e11-48d3-98f7-ee94af3c43ec admin - - - -] Couldn't obtain IP address of instance bfd24135-e279-4b7f-be7a-1aadf593db04

Meanwhile I see no problem with mentioned instances, they are up and running.

(.venv) [root@fuel work]# nova show 5a4c7651-7d3e-4bab-b8ee-fdda9be15703
+--------------------------------------+----------------------------------------------------------+
| Property | Value |
+--------------------------------------+----------------------------------------------------------+
| OS-DCF:diskConfig | AUTO |
| OS-EXT-AZ:availability_zone | nova |
| OS-EXT-SRV-ATTR:host | node-54.domain.tld |
| OS-EXT-SRV-ATTR:hypervisor_hostname | node-54.domain.tld |
| OS-EXT-SRV-ATTR:instance_name | instance-000010bc |
| OS-EXT-STS:power_state | 1 |
| OS-EXT-STS:task_state | - |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2016-04-27T17:03:41.000000 |
| OS-SRV-USG:terminated_at | - |
| accessIPv4 | |
| accessIPv6 | |
| admin_internal_net network | 192.168.108.74 |
| config_drive | |
| created | 2016-04-27T16:58:28Z |
| flavor | gig (e8c39500-0a22-4c25-afe2-f8ed15f61e3d) |
| hostId | 0731685cfe27ffd7fbfb59b032d8496150e63e660e8c2bfc11496a48 |
| id | 5a4c7651-7d3e-4bab-b8ee-fdda9be15703 |
| image | Xenial (9355f643-f72b-4e6f-83cb-124b706ec87e) |
| key_name | - |
| metadata | {} |
| name | StressCPU-7 |
| os-extended-volumes:volumes_attached | [] |
| progress | 0 |
| security_groups | default |
| status | ACTIVE |
| tenant_id | d41dac66d080416ebbd597e0793e5aca |
| updated | 2016-04-27T17:03:41Z |
| user_id | 2a9a8a83ab63483299b69a8f81dbdf35 |
+--------------------------------------+----------------------------------------------------------+

Steps to reproduce:
1. Boot ~20-30 VMs from image (ephemeral volume is used)
2. Keep them up and running for several hours
3. Check logs

Expected results:
1. No ERRORs from ceilometer-polling

Actual result:
1. I see mentioned log entries

Reproducibility:
100%

Workaround:
N/A

Impact:
Unknown. I do not know what it leads to

Description of the environment:
* 10 baremetal nodes:
   - CPU: 12 x 2.10 GHz
   - Disks: 2 drives (SSD - 80 GB, HDD - 931.5 GB), 1006.0 GB total
   - Memory: 2 x 16.0 GB, 32.0 GB total
   - NUMA topology: 1 NUMA node
* Node roles:
  - 1 ElasticSearch / Kibana node
  - 1 InfluxDB / Grafana node
  - 3 controllers (1 was is offline because of disk problems)
  - 5 computes
* Details:
  - OS: Mitaka on Ubuntu 14.04
  - Compute: KVM
  - Neutron with VLAN segmentation
  - Ceph RBD for volumes (Cinder)
  - Ceph RadosGW for objects (Swift API)
  - Ceph RBD for ephemeral volumes (Nova)
  - Ceph RBD for images (Glance)

Additional information:
Diagnostic snapshot: http://mos-scale-share.mirantis.com/env14/fuel-snapshot-2016-04-28_07-46-04.tar.xz