Public bug reported:
When neutron ovs agent assign local vlan to a logic network, the assignment is
non deterministic.
For example, in our deployment, we typically have one or two network associated
to one hypervisor. We expect the local vlan assignment to have vlan tag 1 or 2,
but as the ports get deleted and vlan reclaimed, the vlan assignment would
keeps increasing unexpected.
While there is no functional impact to the data-path, for a large scale
deployment with thousands of hypervisors, we would expect the assignment to be
deterministic and consistent across all hypervisors.
Pre-condition:
neutron network already configured, and is associated with the hypervisor under
test
make the hypervisor clean and no VMs landed on it.
service service neutron-plugin-openvswitch-agent restart
ovs-vsctl show | grep tag
<shows nothing, since no VM is attached yet>
Steps to reproduce the issue.
1. boot one VM on the given hypervisor
nova boot --flavor g1-standard-2 --image <IMG-UUID> cr_sanity
--availability-zone nova:h5wy282
2. on hypervisor
ovs-vsctl show | grep tag
tag: 1
ovs-agent log:
INFO [neutron.plugins.openvswitch.agent.ovs_neutron_agent] 528 [-OVS-AGENT-]
Assigning 1 as local vlan for net-id=ffd84cfd-e7d9-435c-a7c4-61600974d0af
3. delete the first VM.
nova delete <UUID>
INFO [neutron.plugins.openvswitch.agent.ovs_neutron_agent] 629 [-OVS-
AGENT-] Reclaiming vlan = 1 from net-id = ffd84cfd-e7d9-435c-
a7c4-61600974d0af
4. boot another VM on the same hypervisor
nova boot --flavor g1-standard-2 --image <IMG-UUID> cr_sanity
--availability-zone nova:h5wy282
5. on hypervisor
ovs-vsctl show | grep tag
tag: 2
INFO [neutron.plugins.openvswitch.agent.ovs_neutron_agent] 528 [-OVS-
AGENT-] Assigning 2 as local vlan for net-id=ffd84cfd-e7d9-435c-
a7c4-61600974d0af
Expected:
vlan 1 is reclaimed and should be assigned when the VM is spawn the second time.
Actual:
on second time VM is created, vlan 2 is assigned.
Openstack version: stable/kilo
Linux: ubuntu 12.04
** Affects: neutron
Importance: Undecided
Assignee: Aihua Edward Li (aihuaedwardli)
Status: New
** Tags: rfe
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https://bugs.launchpad.net/bugs/1609258
Title:
neutron ml2 local vlan assignment is nondeterministic
Status in neutron:
New
Bug description:
When neutron ovs agent assign local vlan to a logic network, the assignment
is non deterministic.
For example, in our deployment, we typically have one or two network
associated to one hypervisor. We expect the local vlan assignment to have vlan
tag 1 or 2, but as the ports get deleted and vlan reclaimed, the vlan
assignment would keeps increasing unexpected.
While there is no functional impact to the data-path, for a large scale
deployment with thousands of hypervisors, we would expect the assignment to be
deterministic and consistent across all hypervisors.
Pre-condition:
neutron network already configured, and is associated with the hypervisor
under test
make the hypervisor clean and no VMs landed on it.
service service neutron-plugin-openvswitch-agent restart
ovs-vsctl show | grep tag
<shows nothing, since no VM is attached yet>
Steps to reproduce the issue.
1. boot one VM on the given hypervisor
nova boot --flavor g1-standard-2 --image <IMG-UUID> cr_sanity
--availability-zone nova:h5wy282
2. on hypervisor
ovs-vsctl show | grep tag
tag: 1
ovs-agent log:
INFO [neutron.plugins.openvswitch.agent.ovs_neutron_agent] 528 [-OVS-AGENT-]
Assigning 1 as local vlan for net-id=ffd84cfd-e7d9-435c-a7c4-61600974d0af
3. delete the first VM.
nova delete <UUID>
INFO [neutron.plugins.openvswitch.agent.ovs_neutron_agent] 629 [-OVS-
AGENT-] Reclaiming vlan = 1 from net-id = ffd84cfd-e7d9-435c-
a7c4-61600974d0af
4. boot another VM on the same hypervisor
nova boot --flavor g1-standard-2 --image <IMG-UUID> cr_sanity
--availability-zone nova:h5wy282
5. on hypervisor
ovs-vsctl show | grep tag
tag: 2
INFO [neutron.plugins.openvswitch.agent.ovs_neutron_agent] 528 [-OVS-
AGENT-] Assigning 2 as local vlan for net-id=ffd84cfd-e7d9-435c-
a7c4-61600974d0af
Expected:
vlan 1 is reclaimed and should be assigned when the VM is spawn the second
time.
Actual:
on second time VM is created, vlan 2 is assigned.
Openstack version: stable/kilo
Linux: ubuntu 12.04
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