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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
•
dot1ad
is not supported on the main interface. However, untagged frames are supported on the main
interface.
•
Single VLAN is supported as a filtering option for a subinterface, but VLAN list and VLAN range
are not supported.
•
Only MAC address is supported as a filtering option for the main interface.
•
For the filtering option, the destination MAC cannot be combined with inner VLAN or outer VLAN.
•
There is no support for L3 and L4 loopback. Source and destination IP address or source and
destination ports will not be swapped.
•
Connectivity Fault Management (CFM) packets are transparent to the data plane loopback
configuration and cannot be looped back.
•
Packets coming from the other side of the wire where loopback is configured and having the same
destination MAC address are dropped.
•
The broadcast and multicast IP addresses of the broadcast and multicast IP frames that are received
cannot be used as the source IP address of the frame when it is sent back to the initiator. In such a
case, the IP address of the subinterface is used as the source IP address of the frame when it is sent
back to the initiator.
Configuring External Ethernet Data Plane Loopback
Configuring external Ethernet data plane loopback is permitted on a Layer 3 main interface and
subinterfaces.
represents a sample topology to configure Ethernet data plane loopback.
Figure 1
Sample Topology
The following steps show how to configure external Ethernet data plane loopback on a subinterface using
single and double tagging. (The procedure to configure external Ethernet data plane loopback on the
main interface is similar to this procedure.)
SUMMARY STEPS
Step 1
enable
Step 2
configure terminal
Step 3
interface gigabitethernet
slot/port.sub-port
Step 4
encapsulation dot1q
vlan-id
361482
Router 1
Gi 0/0
Gi 0/0.1101
customer 1101
vlan 1101
Gi 0/0.1102
customer 1102
vlan 1102
Gi 0/0.1101
customer 1101
vlan 1101
Gi 0/0.1102
customer 1102
vlan 1102
Gi 0/0
Gi 0/2
Gi 0/2.1101
Gi 0/2.1102
Provider
vlan 100
Carrier
vlan 10
Gi 0/2
Gi 0/2.1101
Gi 0/2.1102
vlan 100
Router 2
Metro Ethernet
361482
Router 1
Gi 0/0
Gi 0/0.1101
customer 1101
vlan 1101
Gi 0/0.1102
customer 1102
vlan 1102
Gi 0/0.1101
customer 1101
vlan 1101
Gi 0/0.1102
customer 1102
vlan 1102
Gi 0/0
Gi 0/2
Gi 0/2.1101
Gi 0/2.1102
Provider
vlan 100
Carrier
vlan 10
Gi 0/2
Gi 0/2.1101
Gi 0/2.1102
vlan 100
Router 2
Metro Ethernet