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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 13 Configuring Interface Characteristics Configuring Layer 3 Interfaces
This example shows how to add a description on a port and how to verify the description:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet1/0/2
Switch(config-if)# description Connects to Marketing
Switch(config-if)# end
Switch# show interfaces gigabitethernet1/0/2 description
Interface Status Protocol Description
Gi1/0/2 admin down down Connects to Marketing
Configuring Layer 3 Interfaces
Note Layer 3 interfaces are not supported on switches running the LAN base feature set.
The switch supports these types of Layer 3 interfaces:
• SVIs: You should configure SVIs for any VLANs for which you want to route traffic. SVIs are
created when you enter a VLAN ID following the interface vlan global configuration command. To
delete an SVI, use the no interface vlan global configuration command. You cannot delete interface
VLAN 1.
Note When you create an SVI, it does not become active until it is associated with a physical port.
For information about assigning Layer 2 ports to VLANs, see Chapter 15, “Configuring
VLANs.”
When configuring SVIs, you can also configure SVI autostate exclude on a port in the SVI to
exclude that port from being included in determining SVI line-state status. See the “Configuring SVI
Autostate Exclude” section on page 13-39.
• Routed ports: Routed ports are physical ports configured to be in Layer 3 mode by using the no
switchport interface configuration command.
• Layer 3 EtherChannel ports: EtherChannel interfaces made up of routed ports.
EtherChannel port interfaces are described in Chapter 40, “Configuring EtherChannels and
Link-State Tracking.”
A Layer 3 switch can have an IP address assigned to each routed port and SVI.
There is no defined limit to the number of SVIs and routed ports that can be configured in a switch or in
a switch stack. However, the interrelationship between the number of SVIs and routed ports and the
number of other features being configured might have an impact on CPU usage because of hardware
limitations. If the switch is using its maximum hardware resources, attempts to create a routed port or
SVI have these results:
• If you try to create a new routed port, the switch generates a message that there are not enough
resources to convert the interface to a routed port, and the interface remains as a switchport.
• If you try to create an extended-range VLAN, an error message is generated, and the extended-range
VLAN is rejected.