Ever wonder what the left column of R’s and S’s in the Interface List meant?
R = Running
“Running” means that the interface is running. In simple terms this means that there is a device plugged into that port. In this screenshot there are devices plugged into ether1, ether2, and ether5.
S = Slave
“Slave” means that the interface is “slaved” to another interface. Being “slaved” means that it acts exactly as its “master” port does. This is how unmanaged switches work. Each port does the same thing, so essentially there is one “master port” and all the others are “slaved” to it. This is how consumer routers works. Port 1 is WAN, ports 2-5 are LAN.
By default, ports ether3, ether4, and ether5 are “slaved” to ether2. Note that the “Name” of each interface is “ether2-master-local”, “ether3-slave-local”, etc. This is only a naming convention. If you made ether5 a Master port, the Name would NOT automagically change to “ether5-master-local”. Just like ether1 doesn’t get named “ether1-gateway” simply because it’s set up as the Gateway. It’s just a label. You could rename ether1 to be “tHa InTeRwEbZ” if you wanted.
RS = Running and Slave
This means there is a device plugged into that port, and that the port is slaved to another.
Interestingly, you won’t see any port statistics (Tx, Rx, Tx Packets, Rx Packets, etc…) for any slaved ports. All of the stats get aggregated into the stats for the Master port – ether2 in this case. If you’re troubleshooting an issue, don’t expect to see any traffic on ether5 even though a device is plugged in. This threw me off at first.