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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Command Reference, Cisco IOS Release 15.1(3)MR
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Chapter Cisco MWR 2941 Router Command Reference, Release 15.1(3)MR
ethernet loopback (interface configuration)
ethernet loopback (interface configuration)
Use the ethernet loopback facility interface configuration command to configure per-port loopbacks
for testing connectivity across multiple devices. Use the no form of this command to remove the
configuration.
ethernet loopback facility [vlan vlan-id] swap [timeout {seconds | none}]
no ethernet loopback
Syntax Description
Command Default No loopbacks are configured. If no mac-address option is configured, the default is to copy the source
and destination addresses.
Command Modes Interface configuration
Command History
Usage Guidelines You can configure Ethernet loopback on physical ports only, not on VLANs or port channels.
A facility loopback puts the port into a state where the link is up, but the line protocol is down for regular
traffic. The device loops back all received traffic.
A port shutdown or a change from a switchport to a routed port ends the loopback.
You can configure one loopback per port, but a maximum of two loopbacks per device. .
Ethernet loopback interactions with other features:
• You cannot configure SPAN and loopback on a switch at the same time. If you try to configure SPAN
on any port on the device while loopback is configured on any port, you receive an error message.
• The port loopback function shares hardware resources with the VLAN-mapping feature. If not
enough TCAM resources are available because of VLAN-mapping configuration, when you attempt
to configure loopback, you receive an error message, and the configuration is not allowed.
• If loopback is active on a port, you cannot add that port to a Flex Link pair or to an Ether Channel.
facility Configure a facility loopback for connectivity testing.
vlan vlan-id Specifies the VLAN that handles loopback traffic. Valid values are 1–4094.
swap Configures the port to swap the MAC source and destination addresses
during loopback.
timeout seconds Configure a loopback timeout period in seconds. The range is from 5 to 300
seconds. There is no default timeout value.
timeout none Configure the loop back to not timeout.
Release Modification
15.1(1)MR This command was introduced.
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