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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring Interface Characteristics
Interface Types
These sections describe the interface types:
• Port-Based VLANs, page 1-2
• Switch Ports, page 1-3
• Routed Ports, page 1-4
• Switch Virtual Interfaces, page 1-5
• EtherChannel Port Groups, page 1-6
• 10-Gigabit Ethernet Interfaces, page 1-7
• Power over Ethernet Ports, page 1-7
• Universal Power Over Ethernet, page 1-13
• Network Module Interfaces, page 1-14
• Connecting Interfaces, page 1-15
Port-Based VLANs
A VLAN is a switched network that is logically segmented by function, team, or application, without
regard to the physical location of the users. For more information about VLANs, see Chapter 1,
“Configuring VLANs.” Packets received on a port are forwarded only to ports that belong to the same
VLAN as the receiving port. Network devices in different VLANs cannot communicate with one another
without a Layer 3 device to route traffic between the VLANs.
VLAN partitions provide hard firewalls for traffic in the VLAN, and each VLAN has its own MAC
address table. A VLAN comes into existence when a local port is configured to be associated with the
VLAN, when the VLAN Trunking Protocol (VTP) learns of its existence from a neighbor on a trunk, or
when a user creates a VLAN. VLANs can be formed with ports across the stack.
To configure VLANs, use the vlan vlan-id global configuration command to enter VLAN configuration
mode. The VLAN configurations for normal-range VLANs (VLAN IDs 1 to 1005) are saved in the
VLAN database. If VTP is version 1 or 2, to configure extended-range VLANs (VLAN IDs 1006 to
4094), you must first set VTP mode to transparent. Extended-range VLANs created in transparent mode
are not added to the VLAN database but are saved in the switch running configuration. With VTP version
3, you can create extended-range VLANs in client or server mode. These VLANs are saved in the VLAN
database.
In a switch stack, the VLAN database is downloaded to all switches in a stack, and all switches in the
stack build the same VLAN database. The running configuration and the saved configuration are the
same for all switches in a stack.
Add ports to a VLAN by using the switchport interface configuration commands:
• Identify the interface.
• For a trunk port, set trunk characteristics, and, if desired, define the VLANs to which it can belong.
• For an access port, set and define the VLAN to which it belongs.
• For a tunnel port, set and define the VLAN ID for the customer-specific VLAN tag. See Chapter 1,
“Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling.”
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