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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-08
Chapter 12 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
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
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
Autostate Exclude” section on page 12-33
.
•
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 38, “Configuring EtherChannels and
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.
•
If the switch is notified by VLAN Trunking Protocol (VTP) of a new VLAN, it sends a message that
there are not enough hardware resources available and shuts down the VLAN. The output of the
show vlan
user EXEC command shows the VLAN in a suspended state.
•
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.
Summary of Contents for Catalyst 3750-E Series
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