Multus 4.0 will provide a thick plugin architecture, and will be useful for incorporating functionality to dynamically attach interfaces during container runtime (as opposed to at container creation and deletion). This type of functionality is desired by CNV, as "interface hot plug" is typical virtual machine behavior, it is also interesting for long-running network-centric workloads such as a vRouter (for example, consider a BGP peer)

Considerations include:

• Upgrade compatibility: e.g. a migration path from thin-to-thick plugin
• Assess current stability and add hardening (as of authoring, Multus 4.0 is in an alpha state upstream)
• Ensuring downstream QE test suite is sufficient for the new architecture
• Upgrades to downstream CI in order to validate functionality moving forward

One possible approach is a "multus mode" option for the CNO Network object that allows us to deploy thick mode, and then conditionally thin mode in cases where we need it in the future (for example: edge computing environments where resources are limited).