What software solutions exist to live stream video over a LAN?

A school is streaming the moing aouncements through a You Tube live stream. The result is great when it works. Frequently the stream is lost for reasons outside of our control (e.g. upstream or downstream inteet coection, Youtube latency, or something else)

The aouncements need to be broadcast to about 60 classrooms (60 computers) and do not really need to be archived on YouTube. What other solutions can we consider?