10-8
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 10 Configuring LAN Ports for Layer 2 Switching
Configuring LAN Interfaces for Layer 2 Switching
Configuring a Layer 2 Switching Port as a Trunk
These section describe configuring a Layer 2 switching port as a trunk:
•
Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk, page 10-8
•
Configuring the Layer 2 Trunk to Use DTP, page 10-9
•
Configuring the Layer 2 Trunk Not to Use DTP, page 10-9
•
Configuring the Access VLAN, page 10-10
•
Configuring the 802.1Q Native VLAN, page 10-10
•
Configuring the List of VLANs Allowed on a Trunk, page 10-11
•
Configuring the List of Prune-Eligible VLANs, page 10-11
•
Completing Trunk Configuration, page 10-12
•
Verifying Layer 2 Trunk Configuration, page 10-12
•
Configuration and Verification Examples, page 10-13
Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk
Note
•
Complete the steps in the
“Configuring a LAN Port for Layer 2 Switching” section on page 10-7
before performing the tasks in this section.
•
When you enter the
switchport
command with no other keywords (
Step 3
in the previous section),
the default mode is
switchport mode dynamic desirable
and
switchport trunk encapsulation
negotiate
.
To configure the Layer 2 switching port as an ISL or 802.1Q trunk, perform this task:
When configuring the Layer 2 switching port as an ISL or 802.1Q trunk, note the following information:
•
The
switchport mode trunk
command (see the
“Configuring the Layer 2 Trunk Not to Use DTP”
section on page 10-9
) is not compatible with the
switchport trunk encapsulation negotiate
command.
•
To support the
switchport mode trunk
command, you must configure the encapsulation as either
ISL or 802.1Q.
•
The following switching modules do not support ISL encapsulation:
–
WS-X6502-10GE
–
WS-X6548-GE-TX, WS-X6548V-GE-TX, WS-X6548-GE-45AF
–
WS-X6148-GE-TX, WS-X6148V-GE-TX, WS-X6148-GE-45AF
Command
Purpose
Router(config-if)#
switchport trunk encapsulation
{
isl
|
dot1q
|
negotiate
}
(Optional) Configures the encapsulation, which configures
the Layer 2 switching port as either an ISL or 802.1Q trunk.
Router(config-if)#
no switchport trunk encapsulation
Reverts to the default trunk encapsulation mode (
negotiate
).