Defining The Allowed Vlans On A Trunk - Cisco WS-C2948G-GE-TX Configuration Manual

Configuring a Trunk Link
Before configuring an 802.1Q trunk you must set a VTP domain and enter the VLANs that will be used
in the trunk or channel. For more information see
"Configuring VLANs."
To configure an 802.1Q trunk, perform this task in privileged mode:
Task
Step 1 Define the VTP domain name.
Step 2
Configure VLANs.
Step 3
Configure an 802.1Q trunk.
Step 4 Verify the trunking configuration.
This example shows how to configure an 802.1Q trunk and verify the trunk configuration:
Console> (enable) set vtp domain Lab_Network
VTP domain Lab_Network modified
Console> (enable) set vlan 10,20,100
VTP advertisements transmitting temporarily stopped,
and will resume after the command finishes.
Vlan 10,20,100 configuration successful.
Console> (enable) set trunk 2/9 desirable dot1q
Port(s) 2/9 trunk mode set to desirable.
Port(s) 2/9 trunk type set to dot1q.
Console> (enable) 07/02/1998,18:22:25:DTP-5:Port 2/9 has become dot1q trunk
Console> (enable) show trunk
Port
--------
2/9
Port
--------
2/9
Port
--------
2/9
Port
--------
2/9
Console> (enable)

Defining the Allowed VLANs on a Trunk

When you configure a trunk port, all VLANs are added to the allowed VLANs list for that trunk.
However, you can remove VLANs from the allowed list to prevent traffic for those VLANs from passing
over the trunk.
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
11-6
Chapter 11
Mode Encapsulation
----------- -------------
desirable dot1q
Vlans allowed on trunk
---------------------------------------------------------------------
1,10,20,100
Vlans allowed and active in management domain
---------------------------------------------------------------------
1,10,20,100
Vlans in spanning tree forwarding state and not pruned
---------------------------------------------------------------------
1,10,20,100
Configuring VLAN Trunks on Fast Ethernet and Gigabit Ethernet Ports
Chapter 9, "Configuring VTP,"
Command
set vtp domain name
set vlan vlan
set trunk mod_num/port_num [on | desirable | auto |
nonegotiate] dot1q
show trunk [mod_num/port_num]
Status Native vlan
------------ -----------
trunking 1
and Chapter 10,
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