Hello,
I think to deploy my old ex4500 before my bgp router in order to count, limit and or filter out udp floods, bum packets and other stuff connected with ddos flooding. Every isp will be terminated on 10G port on ex4500 instead off on my MX router. I need also have port mirror from ingress of every isp which will be terminated on that ex4500. How about performance and cpu impact in this scenario for my old EX4500 
I heard that policers can have quit big impact on cpu but i can't find any details about this. If EX4500 is not perfect for that which Juniper can be (up to 24x10G ports) ?
Thanks for any advice
Ted