Multipoint control unit architectures are ideal for when compute and bandwidth are limited and there is a need for interoperability with disparate networks, but come at a cost of high server load and limiting video layout. On the other hand, selective forwarding unit topologies are ideal for high server performance and maximum flexibility for the client UI but come at a cost of requiring all connecting clients to share the same codec, frame-rate,

A hybrid-SFU/MCU topology allows for the media stream to be delivered based on the preference optimized for the individual client.  For example, in cases where the client is a mobile or SIP device the media server can deliver a single MCU-type mixed stream. For WebRTC clients capable of handling multiple streams and no restrictions on bandwidth or compute, then the media server can deliver forwarded/routed-type streams. Additionally, having the ability to transcode individual streams while leaving all others to be forwarded/routed eliminates the least common codec issue of SFU. Allowing these capabilities to be utilized from within the same media server can give the application server’s business logic the most flexibility in delivering a scalable, reliable, feature-rich service.

If you want to read more about the pros and cons of the different WebRTC architectures, please read our WebRTC MCU/SFU whitepaper.