The type of system I was referring to is the core within the broadcast facility, rather than extending to the home viewers (which is a separate downstream distribution encoding/mux process). Timing is important for when you switch between different video feeds to avoid on-air impacts so all the signals have to be video frame-aligned basically. In an IP system PTP timing is used to lock all the devices since greater precision is needed than NTP can provide.

Low-latency is also important for when the SDN system initiates a route to switch since it generally needs to happen according to a tight broadcast playlist schedule and we found that with SDN (central controller telling all the switches what to do) rather than IGMP type system (multicast subscribe with switches doing a lot more work parsing packets) is the best approach to handling very large volumes of routes and having them take effect in a low-latency predictable way.