ministrative private-vlan trunk Native VLAN tagging: enabled Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative private-vlan trunk private VLANs : none Operational private-vlan: none Trunking VLANs Enabled: 1-99,101-199,201-299,301-4094 Pruning VLANs Enabled: 2-1001 Capture Mode Disabled Capture VLANs Allowed: ALL Protected: false Unknown unicast blocked: disabled Unknown multicast blocked: disabled Appliance trust: none Configuring which VLANs are eligible for pruning is done at the interface level in IOS. The command switchport trunk pruning vlan is used on each trunking interface on the switch where pruning is desired: 3550-IOS (config-if)# switchport trunk pruning vlan ? VLAN IDs of the allowed VLANs when this port is in trunking mode Chapter 6: VLAN Trunking Protocol add VLANs to the current list except all VLANs except the following no VLANs remove remove VLANs from the current list All VLANs are pruning-eligible by default. If you configure VLAN 10 to be eligible for pruning, IOS considers this to mean that only VLAN 10 should be eligible: 3550-I0S(config-if)# switchport trunk pruning vlan 10 3550-I0S(config-if)# No message is displayed telling you that you have just disabled pruning for VLANs 2-99 and 101-1001. You have to look at the interface again to see: 3550-IOS# sho int f0/15 swi Name: Fa0/15 Switchport: Enabled Administrative Mode: trunk Operational Mode: trunk Administrative Trunking Encapsulation: dot1q Operational Trunking Encapsulation: dot1q Negotiation of Trunking: On Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 1 (default) Administrative Native VLAN tagging: enabled Voice VLAN: none Administrative private-vlan host-association: none Administrative private-vlan mapping: none Administrative private-vlan trunk native VLAN: none Administrative private-vlan trunk Native VLAN tagging: enabled Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative p