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."
Finish up ARP/ND support: re-checking bindings, expiring bindings.
Hitless upgrade, especially for data plane.
Use OpenFlow "bundles" for transactional data plane updates.
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.
Reducing startup time.
As-is, if ovsdb-server restarts, every client will fetch a fresh copy of the part of the database that it cares about. With hundreds of clients, this could cause heavy CPU load on ovsdb-server and use excessive network bandwidth. It would be better to allow incremental updates even across connection loss. One way might be to use "Difference Digests" as described in Epstein et al., "What's the Difference? Efficient Set Reconciliation Without Prior Context". (I'm not yet aware of previous non-academic use of this technique.)
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.