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Chapter 11
Configuring Interface Characteristics
Switch Virtual Interfaces
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 you need to configure
an SVI for a VLAN only when you wish to route between VLANs, to 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.
You cannot delete interface VLAN 1.
Note
SVIs provide IP host connectivity only to the system; in Layer 3 mode, you can configure routing across
SVIs.
Although the switch stack or switch supports a total of 1005 VLANs (and SVIs), the interrelationship
between the number of SVIs and routed ports and the number of other features being configured might
impact CPU performance because of hardware limitations. See the
section on page 11-24
reached.
SVIs are created the first time that you enter the vlan interface configuration command for a VLAN
interface. The VLAN corresponds to the VLAN tag associated with data frames on an ISL or
IEEE 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. For more
information, see the
When you create an SVI, it does not become active until it is associated with a physical port.
Note
SVIs support routing protocols and bridging configurations. For more information about configuring IP
routing, see
Routing,"and
The IP base feature set supports static routing and RIP. For more advanced routing or for fallback
Note
bridging, enable the IP services feature set on standalone switch, or the stack master.
SVI Autostate Exclude
The line state of an SVI with multiple ports on a VLAN is in the up state when it meets these conditions:
•
•
•
The protocol link state for VLAN interfaces come up when the first switchport belonging to the
Note
corresponding VLAN link comes up and is in STP forwarding state.
OL-12247-04
for information about what happens when hardware resource limitations are
"Manually Assigning IP Information" section on page
Chapter 38, "Configuring IP Unicast Routing," Chapter 44, "Configuring IP Multicast
Chapter 46, "Configuring Fallback Bridging."
The VLAN exists and is active in the VLAN database on the switch.
The VLAN interface exists and is not administratively down.
At least one Layer 2 (access or trunk) port exists, has a link in the up state on this VLAN, and is in
the spanning-tree forwarding state on the VLAN.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Understanding Interface Types
"Configuring Layer 3 Interfaces"
3-15.
11-5
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