Cisco 2951 - Page 42

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Cisco 3900 Series, Cisco 2900 Series, and Cisco 1900 Series Integrated Services Routers Generation 2 Software Configuration Guide
Chapter Configuring Ethernet CFM and Y.1731 Performance Monitoring on Layer 3 Interfaces
Ethernet Data Plane Loopback
or
encapsulation dot1q vlan-id second-dot1q inner vlan-id
Step 5 ethernet loopback permit external
Step 6 end
DETAILED STEPS
Command Purpose
Step 1
enable
Example:
Router>enable
Enables the privileged EXEC mode.
Enter your password when prompted.
Step 2
configure terminal
Example:
Router#configure terminal
Enters the global configuration mode.
Step 3
interface gigabitethernet
slot/port.sub-port
Example:
Router(config)#interface
gigabitethernet 0/2.1101
Specifies the subinterface and enters the subinterface
configuration mode.
Step 4
encapsulation dot1q vlan-id
or
encapsulation dot1q vlan-id
second-dot1q inner vlan-id
Example:
Router(config-subif)#encapsulation
dot1q 100
or
Router(config-subif)#encapsulation
dot1q 100 second-dot1q 1101
Defines the encapsulation format as IEEE 802.1Q
(dot1q), and specifies the VLAN identifier.
For double tagging, use the second-dot1q keyword and
the inner vlan-id argument to specify the VLAN tag.
Step 5
ethernet loopback permit external
Example:
Router(config-subif)#ethernet
loopback permit external
Configures Ethernet external loopback on the
subinterface.
Step 6
end
Example:
Router(config-subif)#end
Exits the subinterface configuration mode.