Which application do you use to monitor each IP's traffic in the network?

Hi guys,

​

Our network was hit hard by DDOS yesterday, but it takes a long time for our ISP to find out which destination IP was under attacked. To help us identify the attacked IP quicker in the near future, my idea is to mirror and capture the whole traffic by spanning it to another port.

If my idea was familiar, which application is able to achieve that goal? and if there is a tutorial you could link me to it, that would be great.

Thanks.

P/S: Apparently we will install a firewall appliance in the future, so the above question is for learning purposes.

Also, The ISP send us the image below, could you identify which app they are using?

https://imgur.com/a/t0EiLq0