I have a unicast IP flow (no L2 or L3 multicast or broadcast) running between a source device connected to an "access" port in vlan 21 and a destination device connected to an "access" port in vlan 1. Routing between the vlans happens on an external device. I also have a pc connected to another "access" port in vlan 1 that is running a sniffer program. No span/monitor is set up.
Why can I see the unicast flow between the first 2 devices on the "sniffer" pc ?
I thought a switch would only forward packets to a port if the destination mac of the packet matched an entry in the cam table for that port.
