Cisco Systems 3750E manual Interface gigabitethernet1/0/1, Switchport trunk encapsulation, 13-27

Chapter 13 Configuring VLANs

Configuring VLAN Trunks

Figure 13-4 Load-Sharing Trunks with Traffic Distributed by Path Cost

Switch A

Trunk port 1 VLANs 2 – 4 (path cost 30)

VLANs 8 – 10 (path cost 19)

Trunk port 2

VLANs 8 – 10 (path cost 30) VLANs 2 – 4 (path cost 19)

90573

Switch B

Beginning in privileged EXEC mode, follow these steps to configure the network shown in Figure 13-4:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode on Switch A.
Step 2
	interface gigabitethernet1/0/1	Define the interface to be configured as a trunk, and enter interface
		configuration mode.
Step 3
	switchport trunk encapsulation	Configure the port to support ISL or IEEE 802.1Q encapsulation. You
	{isl dot1q negotiate}	must configure each end of the link with the same encapsulation type.
Step 4
	switchport mode trunk	Configure the port as a trunk port. The trunk defaults to ISL trunking.
Step 5
	exit	Return to global configuration mode.
Step 6
		Repeat Steps 2 through 5 on a second interface in Switch A (for a
		Catalyst 3560-E switch) or in the Switch A stack (for a Catalyst 3750-E
		switch).
Step 7
	end	Return to privileged EXEC mode.
Step 8
	show running-config	Verify your entries. In the display, make sure that the interfaces are
		configured as trunk ports.
Step 9
	show vlan	When the trunk links come up, Switch A receives the VTP information
		from the other switches. Verify that Switch A has learned the VLAN
		configuration.
Step 10
	configure terminal	Enter global configuration mode.
Step 11
	interface gigabitethernet1/0/1	Define the interface on which to set the STP cost, and enter interface
		configuration mode.
Step 12
	spanning-tree vlan 2-4 cost 30	Set the spanning-tree path cost to 30 for VLANs 2 through 4.
Step 13
	end	Return to global configuration mode.
Step 14
		Repeat Steps 9 through 13 on the other configured trunk interface on
		Switch A, and set the spanning-tree path cost to 30 for VLANs 8, 9, and
		10.
Step 15
	exit	Return to privileged EXEC mode.
Step 16
	show running-config	Verify your entries. In the display, verify that the path costs are set
		correctly for both trunk interfaces.
Step 17
	copy running-config startup-config	(Optional) Save your entries in the configuration file.
		Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02			13-27