Implementing Trunks参考.ppt

Defining VLANs Implementing Trunks Maintaining Specific VLAN Identification VLAN Trunking Comparing ISL and 802.1Q Trunking with ISL Is a Cisco proprietary protocol Supports PVST Uses an encapsulation process Does not modify the original frame ISL Encapsulation Trunking with 802.1Q An IEEE standard Adds a 4-byte tag to the original frame Additional tag includes a priority field Does not tag frames that belong to the native VLAN Supports Cisco IP telephony The 802.1Q Tagging Process 802.1Q Native VLAN VLAN Ranges Trunking Configuration Commands Configuring a Trunk switchport trunk switchport mode switchport nonegotiate Switchport Mode Interactions How to Configure Trunking Enter interface configuration mode. Shut down interface. Select the encapsulation (802.1Q or ISL). Configure the interface as a Layer 2 trunk. Specify the trunking native VLAN (for 802.1Q). Configure the allowable VLANs for this trunk. Use the no shutdown command on the interface to activate the trunking process. Verify the trunk configuration. 802.1Q Trunk Configuration Verifying the 802.1Q Configuration Verifying a 802.1Q Dynamic Trunk Link Switch#show running-config interface fastethernet 5/8 Building configuration... Current configuration: ! interface FastEthernet5/8 switchport mode dynamic desirable switchport trunk encapsulation dot1q Switch#show interfaces fastethernet 5/8 trunk Port Mode Encapsulation Status Native vlan Fa5/8 desirable 802.1q trunking 99 Port Vlans allowed on trunk Fa5/8 1,5,11,1002-1005 Port Vlans allowed and active in management domain Fa5/8 1,5,1002-1005 Port Vlans in spanning tree forwarding state and not pruned Fa5/8 1,5,1002-1005 ISL Trunk Configuration Verifying ISL Trunking Summary Trunk links carry traffic from multiple VLANs. ISL is Cisco proprietary and encapsulates the Layer 2 frames. 802.1Q is an IEEE standard for trunking, which implements a 4-byte tag. The 802.1Q native