Network throughput is the amount of data actually delivered in a given time, as opposed to a link’s rated speed. Overhead, congestion and slow devices reduce it below the label. A camera network needs throughput for the sum of its streams plus headroom.
A gigabit link rarely delivers a gigabit of video. Throughput is the honest number, and it is what a recorder’s disks and remote viewers compete for.
Add up the streams
Sum the bitrate of every camera at its recording settings. Ten cameras at four megabits each consume forty megabits continuously, which is trivial on gigabit but not on a shared or wireless link.
Where throughput disappears
Wireless links, long cable runs, oversubscribed uplinks and recorders with slow disks all cut effective throughput. Measure the real figure under load instead of trusting the switch specification.