Interaction With Other Features - Cisco Catalyst 2960 Software Configuration Manual

Configuring VLAN Trunks

Interaction with Other Features

Trunking interacts with other features in these ways:
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Configuring a Trunk Port
Beginning in privileged EXEC mode, follow these steps to configure a port as a trunk port:
Command
Step 1 configure terminal
Step 2 interface interface-id
Step 3 switchport mode {dynamic {auto |
desirable} | trunk}
Step 4 switchport access vlan vlan-id
Step 5 switchport trunk native vlan vlan-id
Step 6 end
Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 15.0(1)SE
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A trunk port cannot be a secure port.
Trunk ports can be grouped into EtherChannel port groups, but all trunks in the group must have the
same configuration. When a group is first created, all ports follow the parameters set for the first
port to be added to the group. If you change the configuration of one of these parameters, the switch
propagates the setting you entered to all ports in the group:
allowed-VLAN list.
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STP port priority for each VLAN.
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STP Port Fast setting.
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trunk status: if one port in a port group ceases to be a trunk, all ports cease to be trunks.
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We recommend that you configure no more than 24 trunk ports in PVST mode and no more than 40
trunk ports in MST mode.
If you try to enable IEEE 802.1x on a trunk 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 trunk, the port mode is
not changed.
A port in dynamic mode can negotiate with its neighbor to become a trunk port. If you try to enable
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.
Purpose
Enter global configuration mode.
Specify the port to be configured for trunking, and enter interface
configuration mode.
Configure the interface as a Layer 2 trunk (required only if the interface
is a Layer 2 access port or to specify the trunking mode).
(Optional) Specify the default VLAN, which is used if the interface stops
trunking.
Specify the native VLAN for IEEE 802.1Q trunks.
Return to privileged EXEC mode.
dynamic auto—Set the interface to a trunk link if the neighboring
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interface is set to trunk or desirable mode. This is the default.
dynamic desirable—Set the interface to a trunk link if the
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neighboring interface is set to trunk, desirable, or auto mode.
trunk—Set the interface in permanent trunking mode and negotiate
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to convert the link to a trunk link even if the neighboring interface is
not a trunk interface.
Chapter 13 Configuring VLANs
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