I’ve got a scenario with multiple MT devices on a network, RoMON is setup and working, but fails to discover any devices that are connected through a stack of managed Dell N1548 switches. The devices are reachable via mac-telnet and other devices show up as discoverable via RoMON that are connected elsewhere on the network. However all RoMON traffic is being stopped at the Dell switch. Has anyone else encountered this before? It doesn’t appear to be a config issue on the MT equipment as everything else works fine.
I recall this years ago in similar Dell switch. They filter for non-standard ether-types, like RoMON. A quick google “service-acl” is the feature in “Link Local Protocol Filtering (LLPF)”, but I don’t recall the specific anymore.
yeah, I saw a similar issue on UBNT gear, and I’ve tried messing with the ACL to ensure 0x88bf is allowed but I haven’t had any success yet. Was hoping someone had already solved the issue before since I’m stumped.
Odd. I have similar problem, also Dell.
EOIP tunnel across the switch solved it for me.
But that same switch ( out of my control) doesn’t allow VLAN.
And for that part I’m still stuck.
Maybe I’ll start a new topic for it so I don’t hijack this one 
Don’t have one, docs loosely suggest: “no service-acl input blockall”
If managed, VLANs must be defined to allow them to pass. Dell (used to at least) allow all VLAN tags when the switch was operating in unmanaged mode, for the hardware that had that option. If you don’t have control of the device you’re not going to be able to solve anything.