Cisco WS-C4003 Software Guide - Page 182
Defining the Allowed VLANs on a Trunk
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Configuring a Trunk Link Chapter 11 Configuring VLAN Trunks on Fast Ethernet and Gigabit Ethernet Ports To configure an 802.1Q trunk, perform this task in privileged mode: Task Step 1 Configure an 802.1Q trunk. Step 2 Verify the trunking configuration. Command set trunk mod_num/port_num [on | desirable | auto | nonegotiate] dot1q show trunk [mod_num/port_num] This example shows how to configure an 802.1Q trunk and how to verify the trunk configuration: 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 Mode Encapsulation 2/9 desirable dot1q Status -----------trunking Native vlan ----------1 Port Vlans allowed on trunk 2/9 1-1005 Port Vlans allowed and active in management domain 2/9 1,5,10-32,101-120,150,200,250,300,400,500,600,700,800,900,1000 Port Vlans in spanning tree forwarding state and not pruned 2/9 5,10-32,101-120,150,200,250,300,400,500,600,700,800,900,1000 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. Note When you first configure a port as a trunk, the set trunk command always adds all VLANs to the allowed VLAN list for the trunk, even if you specify a VLAN range (any specified VLAN range is ignored). To modify the allowed VLANs list, use a combination of the clear trunk and set trunk commands to specify the allowed VLANs. To define the allowed VLAN list for a trunk port, perform this task in privileged mode: Step 1 Step 2 Step 3 Task Command Remove VLANs from the allowed VLANs list for clear trunk mod_num/port_num vlans a trunk. (Optional) Add specific VLANs to the allowed set trunk mod_num/port_num vlans VLANs list for a trunk. Verify the allowed VLAN list for the trunk. show trunk [mod_num/port_num] 11-6 Software Configuration Guide-Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4 78-12647-02