In a LAN environment, VLANs divide broadcast domains. When a host in one VLAN must communicate with a host in another VLAN, the traffic must be routed between them. This type of routing is called inter-VLAN routing. On a smart switch, you can set up inter-VLAN routing by creating a Layer 3 interface, that is, a switch virtual interface (SVI).
By default, a port is enabled for bridging rather than routing. With bridging, after an inbound packet is processed, the packet is associated with a VLAN. The MAC destination address (MAC DA) of the packet and the VLAN ID are then used to search the MAC address table.
If you enable routing for the VLAN, and the MAC DA of an inbound unicast packet is that of the internal bridge-router interface, the packet is routed. The smart switch forwards an inbound multicast packet to all ports in the VLAN. If the packet enters on a routed VLAN, the smart switch also forwards the packet to the internal bridge-router interface.
Because a port can be member of more than one VLAN, VLAN routing might be enabled for all of the VLANs on the port, or for a subset. You can use VLAN routing to allow more than one physical port to reside on the same subnet, to span a VLAN over multiple physical networks, or to provide additional segmentation or security. A port can be either a VLAN port or a router port, but not both. However, a VLAN port might be part of a VLAN that is itself a router port.
For information about configuring VLAN Routing a smart switch, see the “How do I configure VLAN Routing on a smart switch?
Last Updated:11/28/2016
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Article ID: 24754