[dfe]

It's common for wake-on-LAN clients to send UDP packets to port 9 to make sure they get discarded. This is particularly useful if using a multicast or broadcast destination, which is often the case because the ARP entry will have been discarded by the time you need to send the packet.

The hardware that looks for the magic packet ignores the framing.

I certainly wouldn't run a TCP discard service, but making sure that UDP packets to port 9 do not result in any ICMP port unreachable response, or any other response, is a good practice.