If there is a need for something more reliable than SPAN port, actually with 100% traffic copy reliability Garland Technology TAP devices are the bast possible choice. With TAP device you can easily copy traffic flow and send it to some monitoring device in your network (like Darktrace). If there is a need for more intelligent device that can do filtering, aggregation, load balancing, deduplication, times stamping Garland Technology Network Packet Brokers are the devices of choice.