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OVN To-do List

  • Refactor ovn-northd code to have separate functions to add logical flows for gateway logical routers and logical routers with distributed gateway port.

  • Get incremental updates in ovn-controller and ovn-northd in some sensible way.

  • Live migration.

    Russell Bryant: "When you're ready to have the destination take over, you have to remove the iface-id from the source and add it at the destination and I think it'd typically be configured on both ends, since it's a clone of the source VM (and it's config)."

  • VLAN trunk ports.

    Russell Bryant: "Today that would require creating 4096 ports for the VM and attach to 4096 OVN networks, so doable, but not quite ideal."

  • Service function chaining.

  • MAC learning.

    Han Zhou: "To support VMs that hosts workloads with their own macs, e.g. containers, if not using OVN native container support."

  • Hitless upgrade, especially for data plane.

  • Dynamic IP to MAC binding enhancements.

    OVN has basic support for establishing IP to MAC bindings dynamically, using ARP.

    • Ratelimiting.

      From casual observation, Linux appears to generate at most one ARP per second per destination.

      This might be supported by adding a new OVN logical action for rate-limiting.

    • Tracking queries

      It's probably best to only record in the database responses to queries actually issued by an L3 logical router, so somehow they have to be tracked, probably by putting a tentative binding without a MAC address into the database.

    • Renewal and expiration.

      Something needs to make sure that bindings remain valid and expire those that become stale.

      One way to do this might be to add some support for time to the database server itself.

    • Table size limiting.

      The table of MAC bindings must not be allowed to grow unreasonably large.

  • MTU handling (fragmentation on output)

  • ovsdb-server

    ovsdb-server should have adequate features for OVN but it probably needs work for scale and possibly for availability as deployments grow. Here are some thoughts.

    • Multithreading.

      If it turns out that other changes don't let ovsdb-server scale adequately, we can multithread ovsdb-server. Initially one might only break protocol handling into separate threads, leaving the actual database work serialized through a lock.

  • Support multiple tunnel encapsulations in Chassis.

    So far, both ovn-controller and ovn-controller-vtep only allow chassis to have one tunnel encapsulation entry. We should extend the implementation to support multiple tunnel encapsulations.

  • Update learned MAC addresses from VTEP to OVN

    The VTEP gateway stores all MAC addresses learned from its physical interfaces in the 'Ucast_Macs_Local' and the 'Mcast_Macs_Local' tables. ovn-controller-vtep should be able to update that information back to ovn-sb database, so that other chassis know where to send packets destined to the extended external network instead of broadcasting.

  • Translate ovn-sb Multicast_Group table into VTEP config

    The ovn-controller-vtep daemon should be able to translate the Multicast_Group table entry in ovn-sb database into Mcast_Macs_Remote table configuration in VTEP database.

  • OVN OCF pacemaker script to support Active / Passive HA for OVN dbs provides the option to configure the inactivity_probe value. The default 5 seconds inactivity_probe value is not sufficient and ovsdb-server drops the client IDL connections for openstack deployments when the neutron server is heavily loaded.

    We need to find a proper solution to solve this issue instead of increasing the inactivity_probe value.

  • ACL

    • Support FTP ALGs.
    • Support reject action.

  • OVN Interconnection

    • Packaging for RHEL, Debian, etc.

  • ovn-controller: Remove backwards compatibility for Southbound DB Port_Group names in expr.c a few releases after the 20.09 version. Right now ovn-controller maintains backwards compatibility when connecting to a SB database that doesn't store Port_Group.name as <Logical_Datapath.tunnel_key_NB-Port_Group.name>. This causes an additional hashtable lookup in parse_port_group() which can be avoided when we are sure that the Southbound DB uses the new format.

  • ovn-northd-ddlog: Calls to warn() and err() from DDlog code would be better refactored to use the Warning[] relation (and introduce an Error[] relation once we want to issue some errors that way). This would be easier with some improvements in DDlog to more easily output to multiple relations from a single production.

  • IP Multicast Relay

    • When connecting bridged logical switches (localnet) to logical routers with IP Multicast Relay enabled packets might get duplicated. We need to find a way of determining if routing has already been executed (on a different hypervisor) for the IP multicast packet being processed locally in the router pipeline.

  • ovn-controller Incremental processing

    • physical.c has a global simap -localvif_to_ofport which stores the local OVS interfaces and the ofport numbers. Move this to the engine data of the engine data node - ed_type_pflow_output.
    • Implement I-P for datapath groups.

  • ovn-northd parallel logical flow processing

    • Multi-threaded logical flow computation was optimized for the case when datapath groups are disabled. Datpath groups are always enabled now so northd parallel processing should be revisited.

  • ovn-controller daemon module

    • Dumitru Ceara: Add a new module e.g. ovn/lib/daemon-ovn.c that wraps OVS' daemonize_start() call and initializes the additional things, like the unixctl commands. Or, we should move the APIs such as daemon_started_recently() to OVS's lib/daemon.

  • Chassis_Template_Var

    • Support template variables when tracing packets with ovn-trace.

  • Load Balancer templates

    • Support combining the VIP IP and port into a single template variable.