The routing software and hardware routes IP traffic between router interfaces. A router interface is simply a virtual LAN (VLAN) that has an IP address assigned to it.
As you create VLANs with IP addresses belonging to different IP subnets, you can also choose to route between the VLANs. Both the VLAN switching and IP routing function occur within the switch.
NoteEach IP address and mask assigned to a VLAN must represent a unique IP subnet. You cannot configure the same IP address and subnet on different VLANs.
Routing Between VLANs shows an example switch configuration with two VLANs defined: Finance and Personnel. All ports on slots 1 and 3 are assigned to Finance, and all ports on slots 2 and 4 are assigned to Personnel. The figure shows the subnet address and interface address for each VLAN. Traffic within each VLAN is switched using the Ethernet MAC addresses. Traffic between the two VLANs is routed using the IP addresses.