Default Layer 2 Ethernet Interface Vlan Configuration; How To Configure Vlan Trunks - Cisco Catalyst 2960 series Configuration Manual

Default Layer 2 Ethernet Interface VLAN Configuration

• We recommend that you configure no more than 24 trunk ports in Per VLAN Spanning Tree (PVST)
• If you try to enable IEEE 802.1x on a trunk port, an error message appears, and IEEE 802.1x is not
• A port in dynamic mode can negotiate with its neighbor to become a trunk port. If you try to enable
Default Layer 2 Ethernet Interface VLAN Configuration
The following table shows the default Layer 2 Ethernet interface VLAN configuration.
Table 11: Default Layer 2 Ethernet Interface VLAN Configuration
Feature
Interface mode
Allowed VLAN range
VLAN range eligible for pruning
Default VLAN (for access ports)
Native VLAN (for IEEE 802.1Q trunks)

How to Configure VLAN Trunks

To avoid trunking misconfigurations, configure interfaces connected to devices that do not support DTP to
not forward DTP frames, that is, to turn off DTP.
• If you do not intend to trunk across those links, use the switchport mode access interface configuration
• To enable trunking to a device that does not support DTP, use the switchport mode trunk and switchport
Catalyst 2960-X Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX
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mode and no more than 40 trunk ports in Multiple Spanning Tree (MST) mode.
enabled. If you try to change the mode of an IEEE 802.1x-enabled port to trunk, the port mode is not
changed.
IEEE 802.1x on a dynamic port, an error message appears, and IEEE 802.1x is not enabled. If you try
to change the mode of an IEEE 802.1x-enabled port to dynamic, the port mode is not changed.
command to disable trunking.
nonegotiate interface configuration commands to cause the interface to become a trunk but to not
generate DTP frames.
Default Setting
switchport mode dynamic auto
VLANs 1 to 4094
VLANs 2 to 1001
VLAN 1
VLAN 1
Configuring VLAN Trunks
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