7-10
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
78-14099-04
Chapter 7 Configuring LAN Ports for Layer 2 Switching
Configuring LAN Interfaces for Layer 2 Switching
To configure the Layer 2 trunk not to use DTP, perform this task:
When configuring the Layer 2 trunk not to use DTP, note the following syntax information:
• Before entering the switchport mode trunk command, you must configure the encapsulation (see
the “Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk” section on page 7-8).
• To support the switchport nonegotiate command, you must enter the switchport mode trunk
command.
• Enter the switchport mode dynamic trunk command. See Table 7-2 on page 7-4 for information
about trunking modes.
• Before entering the switchport nonegotiate command, you must configure the encapsulation (see
the “Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk” section on page 7-8) and
configure the port to trunk unconditionally with the switchport mode trunk command (see the
“Configuring the Layer 2 Trunk to Use DTP” section on page 7-9).
Note Complete the steps in the “Completing Trunk Configuration” section on page 7-13 after performing the
tasks in this section.
Configuring the Default VLAN
Note Complete the steps in the “Preparing a Layer 2 Switching Port for Configuration as a Trunk” section on
page 7-8 before performing the tasks in this section.
To configure the default VLAN, perform this task:
Command Purpose
Step 1
Router(config-if)# switchport mode trunk
(Optional) Configures the port to trunk unconditionally.
Router(config-if)# no switchport mode
Reverts to the default trunk trunking mode (switchport
mode dynamic desirable).
Step 2
Router(config-if)# switchport nonegotiate
(Optional) Configures the trunk not to use DTP.
Router(config-if)# no switchport nonegotiate
Enables DTP on the port.
Command Purpose
Router(config-if)# switchport access vlan vlan_ID
(Optional) Configures the default VLAN, which is used if the
interface stops trunking.
• With Release 12.1(13)E and later releases, the vlan_ID
value can be 1 to 4094, except for reserved VLANs (see
Table 9-1 on page 9-2).
• With 12.1 E releases earlier than Release 12.1(13)E, the
vlan_ID value can be 1 to 1005.
Router(config-if)# no switchport access vlan
Reverts to the default value (VLAN 1).
