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Cisco 3200 Series Router Hardware Reference
OL-5816-10
Appendix C Switch Port Functionality
Switch Virtual Interface
Switch Virtual Interface
A Switch Virtual Interface (SVI) represents a VLAN of switch ports as one interface to the routing or
bridging function in the system. Only one SVI can be associated with a VLAN, but it is necessary to
configure an SVI for a VLAN only when you wish to route between VLANs, fallback-bridge
nonroutable protocols between VLANs, or to provide IP host connectivity to the switch. By default, an
SVI is created for the default VLAN (VLAN 1) to permit remote switch administration. Additional SVIs
must be explicitly configured. In Layer 2 mode, SVIs provide IP host connectivity only to the system;
in Layer 3 mode, you can configure routing across SVIs.
SVIs are created the first time that you enter the vlan interface configuration command on a VLAN
interface. The VLAN corresponds to the VLAN tag associated with data frames on an ISL or 802.1Q
encapsulated trunk or the VLAN ID configured for an access port. Configure a VLAN interface for each
VLAN for which you want to route traffic, and assign it an IP address.
SVIs support routing protocol and bridging configurations.

Creating a SVI

To make any of the 2-port FESMIC or the 4-port FESMIC switchports routable, do the following:
Step 1 Create a VLAN ID that will be used for the VLAN.
Step 2 From the enable prompt, (not the global configuration prompt) enter the following commands:
Router#vlan database
! your prompt is now "Router(vlan)#"
Router(vlan)#vlan
7
Router(vlan)#exit
Note If you skip Step 2, your switchport virtual interface line protocol will be down.
Step 3 Go to global configuration mode and enter your switchport.
Router>conf t
Router#interface FastEthernet
3/0
Router(config-if)#switchport access vlan
7
Step 4 Configure the IP address for the interface by entering the SVI
Router(config-if)#interface configuration:
Router(config-if)#interface vlan
7
Router(config-if)#ip address
7.7.7.7 255.255.255.0
The 10/100 Fast Ethernet 3/0 switchport can be pinged by through the VLAN interface. You can now
attach any Layer 3 features to interface with the VLAN.