Cisco me 3400 Guia Do Programa

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 

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 

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. 
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 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 switch port.

If you try to create an extended-range VLAN, an error message is generated, and the extended-range 
VLAN is rejected.

If the switch attempts to boot up with a configuration that has more VLANs and routed ports than 
hardware can support, the VLANs are created, but the routed ports are shut down, and the switch 
sends a message that this was due to insufficient hardware resources.

All Layer 3 interfaces require an IP address to route traffic. This procedure shows how to configure an 
interface as a Layer 3 interface and how to assign an IP address to an interface.

If the physical port is in Layer 2 mode (the default), you must enter the no switchport interface 
configuration command to put the interface into Layer 3 mode. Entering a no switchport command 
disables and then re-enables the interface, which might generate messages on the device to which the 
interface is connected. Furthermore, when you put an interface that is in Layer 2 mode into Layer 3 
mode, the previous configuration information related to the affected interface might be lost, and the 
interface is returned to its default configuration

Beginning in privileged EXEC mode, follow these steps to configure a Layer 3 interface:

Enter global configuration mode.

interface {{fastethernet | gigabitethernet} interface-id} 
| {vlan vlan-id} | {port-channel port-channel-number}

Specify the interface to be configured as a Layer 3 
interface, and enter interface configuration mode.

Enable the port, if necessary. By default, UNIs and ENIs 
are disabled, and NNIs are enabled.

For physical ports only, enter Layer 3 mode.

ip address ip_address subnet_mask 

Configure the IP address and IP subnet.

Enable the interface.

Return to privileged EXEC mode.