After reading a bit about inter VLAN routing I have a doubt regarding how trunking takes place at router and at switch. In the case of the switch we configured a port interface as trunk port and all vlan's are allowed here but in the case of the router we configured a sub interface as trunk saying particular vlan belongs to particular subinterface. Can't we configure only a single port interface on router just like switch and say all vlan's are allowed here on this interface? Why to go for sub interfaces?
Hope I'm able to put my question in right way.