[openstack-dev] [networking-ovn][Neutron] OVN support for routed networks(plugin interface for host mapping)

Hong Hui Xiao xiaohhui at cn.ibm.com
Wed Mar 16 02:02:03 UTC 2016

Hi all.

I did some investigation recently. And I think we can start some
discussion now.

All below thinking is based on the current implementation of neutron. With
routed network, a subnet will be considered as a L2 domain. Things might

I think routed network in OVN can implement in this way:
User creates provider network. For example:
neutron net-create provider-101 --shared \
--provider:physical_network providernet \
--provider:network_type vlan \
--provider:segmentation_id 101

These attributes "--provider:physical_network" will be recorded in the
external_ids of Logical_Switch in OVN_Northbound.

To Russell:
I will expect OVN to do the following things.
1) The OVN_Southbound will have the latest information of
"ovn-bridge-mappings" of each Chassis.
2) After creating a new network with "provider:physical_network" set, the
OVN will update Logical_Switch in OVN_Northbound.
The Logical_Switch will have new key:value pair in external_ids.
3) When a compute host join/leave the OpenStack topology, or a compute
host just updates its ovn-bridge-mappings, OVN should updated
Logical_Switch with related physical_network. This is a bottom-up change,
which is similar to the port status change.
4) networking-ovn should be able to catch the update of Logical_Switch in
2) & 3) and update the SegmentHostMapping, which will be introduced in

I think 1) 2) & 3) need additional work in OVN code. And 4) need code
change in networking-ovn.

To Carl:
At the same time, the plugin(ml2 or networking-ovn) will provide a "new"
interface. The "new" interface might be the same with [1].
Neutron will use this interface select routed hosts for a network.

Any thoughts?

[1] neutron.plugins.ml2.plugin.Ml2Plugin.filter_hosts_with_network_access 
@  https://review.openstack.org/#/c/205631/33
[2] https://review.openstack.org/#/c/285548/1


HongHui Xiao(肖宏辉) PMP®
OpenStack Network development, Beijing, China

Email: xiaohhui at cn.ibm.com 
Tel: 86-10-82453130

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