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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-12247-04
Chapter 11 Configuring Interface Characteristics
Understanding Interface Types
•
Connecting Interfaces, page 11-7
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
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. In a switch stack, 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
“Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling.”
Switch Ports
Switch ports are Layer 2-only interfaces associated with a physical port. Switch ports belong to one or
more VLANs. A switch port can be an access port, a trunk port, or a tunnel port. You can configure a
port as an access port or trunk port or let the Dynamic Trunking Protocol (DTP) operate on a per-port
basis to set the switchport mode by negotiating with the port on the other end of the link. You must
manually configure tunnel ports as part of an asymmetric link connected to an IEEE 802.1Q trunk port.
Switch ports are used for managing the physical interface and associated Layer 2 protocols and do not
handle routing or bridging.
Configure switch ports by using the
switchport
interface configuration commands. Use the
switchport
command with no keywords to put an interface that is in Layer 3 mode into Layer 2 mode.
Note
When you put an interface that is in Layer 3 mode into Layer 2 mode, the previous configuration
information related to the affected interface might be lost, and the interface is returned to its default
configuration.
