OVN and Openstack - Configuration and interfaces assignment

asked 2020-05-23 06:10:35 -0500

Marco Marino gravatar image

updated 2020-05-23 09:55:26 -0500

Hi, I'm trying to understand how ovn in openstack works and I'm focused on a particular kind of configuration: One controller node and N compute nodes with distributed virtual router. Please, excuse me if I'm going to ask stupid questions, but I have doubts about this even after tried to search in documentation. Basically I need to know if some assumptions are true:

1) If I use distributed virtual routing and I have provider networks (flat or vlans, not important), I have to connect all compute nodes to the overlay network AND to the provider network. Is this true? Furthermore, I have to connect compute nodes to the management network, so in total I need at least 3 network interface card for each compute node. Please give me a feedback on this.

2) I studied OVN and it seems to me that the connection between the ovn-controller (on compute nodes) and southbound database use the management network and not the overlay network. It makes sense in my opinion because in this way there is a real separation between control plane and data plane. So, can I avoid to connect the openstack controller node to the overlay network? if this is true, it seems that I need only 1 interface on the openstack controller node, just for management. Is this correct? (yes, I know I can connect external network, api network and so on... but minimal functionality can be obtained only with management network in a basic installation)

3) In a configuration where DVR is active, what is the purpose of the gateway node? (please use this reference architecture: https://docs.openstack.org/networking... ). It seems to me that I can completely remove the gateway node.

Thank you,

Marco

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Comments

1- yes, though you can run several types of traffic on the same network. Also, in production it's common to deploy nodes with single NICs (or single NIC bonds) and put the traffic types on different VLANs.

Bernd Bausch gravatar imageBernd Bausch ( 2020-05-23 20:14:31 -0500 )edit

3- You can deploy OVN on a single computer if you like. Example: Packstack. My guess is that the reference architecture tries to come closer to a realistic setup, where you probably need some load balancing over several servers.

Bernd Bausch gravatar imageBernd Bausch ( 2020-05-23 20:16:13 -0500 )edit