Hello @dhikra-marghli8 ,
1) Duplicate ethernet frames cannot be detected at Ethernet OSI layer 2, upper layer protocols with flow control like TCP can detect duplicated packets. Duplication of ethernet frames do not happen in a a stable loop free L2 LAN topology.
2) Per port input storm control can be used. However, we cannot discriminate between expected broadcast frames and unwanted ones. We can instruct the switch to accept a max percentage of port speed bandwidth for each BUM category , Broadcast, Unknown unicast , Multicast. The feature works inbound on 1sec time intervals if the threshold is crossed all traffic for the category is dropped.
Configuration of storm control is recommended as a way to help STP to handle some dynamic topology changes that create bridiging loops. During a bridiging loop a broadcast storm can be created that can fill all the available BW in all ports if storm control is not deployed.
Just to make an example on an access port 1GE we can use a broadcast storm control of 1% or just a little more with no issue with subnets like /24 or more specific.
The use of storm control can save an on site trip in case of issues you may have the time to enter on a distribution switch and to shut one or more ports to break a bridging loop.
3) Storm control on LAN switches. Rate limiting of broadcast traffic is possible on PE nodes access interfaces for L2 MPLS services like VPLS.
Hope to help
Giuseppe
