I've got a Dell 5424 with about 20 machines directly attached to it. I did a ping sweep of my network (and got answers from all 20), then went to the CLI of the switch and did
show arp. To my surprise, I only see two arp entries: one for my router, and one for the machine I'm SSHed into to do this work.
What the heck is going on here? It's not that there's another switch in place, these machines are directly connected to the switch. Is my expectation of all those arp entries on my switch mistaken?
If I use
ping (machine) from the CLI, that machine's MAC shows up on the port I would expect it to in the arp table. The arp timeout is set to 3600, which seems a bit low to me, but is the default on this switch. The time between my ping sweep and my
show arp was way lower than that.