In the latest routers, where switching function is integrated into the box will have few LAN ports (say usually, 4 or 8) and 1 WAN port.
Usual configuration would be to connect computers or printers onto the LAN port and WAN port onto the modem to connect to the internet.
So is it like the LAN ports are nothing but the ports of the integrated switch? And WAN port is used to connect to a separate subnet, say to an another switch or to an another router?
(Internally, it would be like integrated switch is connected to an another hidden WAN port*)
Best Answer
You have the right idea.Internally these devices are VLAN switches with exposed ports a member of a single vlan + a single port computer to do routing between vlans and configured to look like a dumb switch and wan port
If you can run it, DD-WRT for example - exposes the internal workings somewhat - typically all 5 ports - the WAN port included - are VLAN switch ports- with another invisible VLAN trunk port on the motherboard.
It is thus (software permitting - and most software does not) possible to combine ports so they are all on the same VLAN and appear as a dumb switch, or you can break them out on to separate vlans and have multiple "WAN" ports, or multiple lan subnets.
It is certainly possible to connect the WAN port to a separate subnet, say to an another switch or to an another router - really, that, and having a route table is the core requirement of a router.