Tue Jan 12, 2021 6:17 pm
Port mirroring is a feature of the switch chip, so its availability as such depends on your hardware model. Even switch chips which do support it can only use one of the Ethernet ports as the mirror destination, so you have to connect the mirror destination Ethernet port to another one using a patchcord, and bridge that other port with the L2 tunnel using a software bridge in order to forward the traffic somewhere else. You have to set protocol-mode=none on that bridge, otherwise it would filter some frame types, and you must be careful not to create an L2 loop by returning the mirrored frames back to the mirror source port somehow.
And of course the tunnel must not run through the mirror source port.
Since the mirroring mirrors both traffic directions of the mirror source port, it cannot run at full bandwidth in both directions as the Tx bandwidth of the mirror destination port would be exceeded.