You can see this from the new topology view (at least if you have a switch in the network). Below you can see that port 3 on the MX is connected to port 8 on the switch. Note that this is LAN port 3 on this MX75 which is actually labelled 7 on the unit as they start from 0 and the first three ports are WAN ports.
![1000009882.jpg 1000009882.jpg](https://community.meraki.com/t5/image/serverpage/image-id/37300i63BE5833EB2C9DF3/image-size/medium?v=v2&px=400)