Specifications

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Catalyst 2970 Switch Software Configuration Guide
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Chapter 11 Configuring VLANs
Configuring VLAN Trunks
• VLANs 8 through 10 retain the default port priority of 128 on Trunk 2.
In this way, Trunk 1 carries traffic for VLANs 8 through 10, and Trunk 2 carries traffic for VLANs 3
through 6. If the active trunk fails, the trunk with the lower priority takes over and carries the traffic for
all of the VLANs. No duplication of traffic occurs over any trunk port.
Figure 11-3 Load Sharing by Using STP Port Priorities
Beginning in privileged EXEC mode, follow these steps to configure the network shown in Figure 11-3.
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Switch A
Switch B
Trunk 2
VLANs 3 – 6 (priority 16)
VLANs 8 – 10 (priority 128)
Trunk 1
VLANs 8 – 10 (priority 16)
VLANs 3 – 6 (priority 128)
Command Purpose
Step 1
configure terminal Enter global configuration mode on Switch A.
Step 2
vtp domain domain-name Configure a VTP administrative domain.
The domain name can be from 1 to 32 characters.
Step 3
vtp mode server Configure Switch A as the VTP server.
Step 4
end Return to privileged EXEC mode.
Step 5
show vtp status Verify the VTP configuration on both Switch A and Switch B.
In the display, check the VTP Operating Mode and the VTP Domain
Name fields.
Step 6
show vlan Verify that the VLANs exist in the database on Switch A.
Step 7
configure terminal Enter global configuration mode.
Step 8
interface gigabitethernet 0/1 Enter interface configuration mode, and define Gigabit Ethernet
port 0/1 as the interface to be configured as a trunk.
Step 9
switchport trunk encapsulation {isl |
dot1q | negotiate}
Configure the port to support ISL or 802.1Q encapsulation or to
negotiate with the neighboring interface. You must configure each
end of the link with the same encapsulation type.
Step 10
switchport mode trunk Configure the port as a trunk port.
Step 11
end Return to privileged EXEC mode.
Step 12
show interfaces gigabitethernet 0/1
switchport
Verify the VLAN configuration.
Step 13
Repeat Steps 7 through 11 on Switch A for a second interface in the
switch.
Step 14
Repeat Steps 7 through 11 on Switch B to configure the trunk ports
that connect to the trunk ports configured on Switch A.