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13-13
Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 13 Configuring VLANs
Displaying VLANs
Displaying VLANs
Use the show vlan privileged EXEC command to display a list of all VLANs on the switch, including
extended-range VLANs. The display includes VLAN status, ports, and configuration information.
Table 13-3 lists the privileged EXEC commands for monitoring VLANs.
For more details about the show command options and explanations of output fields, see the command
reference for this release.
Configuring VLAN Trunks
These sections contain this conceptual information:
• Trunking Overview, page 13-13
• Default Layer 2 Ethernet Interface VLAN Configuration, page 13-15
• Configuring an Ethernet Interface as a Trunk Port, page 13-15
• Configuring Trunk Ports for Load Sharing, page 13-19
Trunking Overview
A trunk is a point-to-point link between one or more Ethernet switch interfaces and another networking device
such as a router or a switch. Ethernet trunks carry the traffic of multiple VLANs over a single link, and you
can extend the VLANs across an entire network. The switch supports IEEE 802.1Q encapsulation.
You can configure a trunk on a single Ethernet interface or on an EtherChannel bundle. For more
information about EtherChannel, see Chapter 37, “Configuring EtherChannels and Link-State
Tracking.”
Ethernet trunk interfaces support different trunking modes (see Table 13-4). You can set an interface as
trunking or nontrunking or to negotiate trunking with the neighboring interface. To autonegotiate
trunking, the interfaces must be in the same VTP domain.
Trunk negotiation is managed by the Dynamic Trunking Protocol (DTP), which is a Point-to-Point
Protocol. However, some internetworking devices might forward DTP frames improperly, which could
cause misconfigurations.
Table 13-3 VLAN Monitoring Commands
Command Purpose
show interfaces [vlan
vlan-id]
Display characteristics for all interfaces or for the specified VLAN configured on the switch.
show vlan [id vlan-id] Display parameters for all VLANs or the specified VLAN on the switch.