Gaps from ML2/OVS

This is a list of some of the currently known gaps between ML2/OVS and OVN. It is not a complete list, but is enough to be used as a starting point for implementors working on closing these gaps. A TODO list for OVN is located at 1.

  • QoS DSCP support

    Currently ML2/OVS supports QoS DSCP tagging and egress bandwidth limiting. Those are basic QoS features that while integrated in the OVS/OVN C core are not integrated (or fully tested) in the neutron OVN mechanism driver.

  • QoS for Layer 3 IPs

    Currently the Neutron L3-agent supports floating IP and gateway IP bandwidth limiting based on Linux TC. OVN L3 plugin supports floating IP bandwidth limiting based on the OVN’s QoS rules. Neutron OVN backend does not yet support bandwidth limiting for gateway IP.

  • QoS Minimum Bandwidth support

    Currently ML2/OVS supports QoS Minimum Bandwidth limiting, but it is not supported in OVN.

  • BGP support

    Currently ML2/OVS supports making a tenant subnet routable via BGP, and can announce host routes for both floating and fixed IP addresses.

  • Baremetal provisioning with iPXE

    The core OVN DHCP server implementation does not have support for sending different boot options based on the gpxe DHCP Option (no. 175). Also, Ironic uses dnsmasq syntax when configuring the DHCP options for Neutron 2 which is not understood by the OVN driver.

  • QoS minimum bandwidth allocation in Placement API

    ML2/OVN integration with the Nova placement API to provide guaranteed minimum bandwidth for ports 3.

  • IPv6 Prefix Delegation

    Currently ML2/OVN doesn’t implement IPv6 prefix delegation. OVN logical routers have this capability implemented in 4 and we have an open RFE to fill this gap 5.

  • East/West Fragmentation

    The core OVN implementation does not support east/west fragmentation. There is no known production use-case for this feature hence we don’t even have an RFE open for it and it’s not on the roadmap to be implemented.