switchport block multicast vs storm-control multicast I'm not sure what is the difference in behaviour between `switchport block multicast` and `storm-control multicast` and I don't think cisco elaborates the difference very well in their documentation, other than the fact storm-control grants you levels of control, but for this case, suppose the storm-control only lets you pick up 0 or 100. How is it any different from switchport block, for instance? Update: I accidentally wrote "switchport block unicast" when I intended to write "switchport block multicast".

Well the first difference would be that `switchport block unicast` blocks unknown unicast and `storm-control multicast` blocks multicast packets.

The difference between `switchport block XXXcast` and `storm-control XXXcast` is exactly what you want to exclude in your question. You can pick any percent value for `storm-control`. It will block traffic of the specified type which exceeds this percentage of bandwidth on the port. `switchport block` is a simple yes/no. It blocks everything when activated.

**Update:**

As ytti mentioned, on some low-end boxes when `storm-control multicast` is exceeded all traffic will get filtered. In that case `storm-control multicast` is dangerous and useless.

Also on high-bandwidth interfaces (1/10GE) please remember that even a small percentage of the bandwidth can kill a box that punts the packets to the CPU. If possible use CoPP to protect the control plane. Also always use pps instead of bps for CoPP if possible.