New packet-per-second (pps)-based policer for transit and control traffic

A new pps-based policer is available at the [edit firewall policer policer-name] hierarchy level. This new policer is configured using the if-exceeding-pps configuration statement. Compared to bandwidth-based policers, the pps-based policer is more effective at combating low-and-slow types of DDoS attacks. The pps-based policer can be applied in the same manner and the same locations as bandwidth-based policers, but it cannot be used as a percentage-based policer.