Specifications

17-48
System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches
Chapter 17 Configuring Ethernet OAM, CFM, and E-LMI
Enabling Ethernet Loopback
• When you configure VLAN loopback by entering the vlan vlan-list keywords, the VLANs are
tunneled into an internal VLAN that is not forwarded to any ports. The tunnel ends at the egress, so
it is transparent to the user.
• VLAN loopback is not supported on nontrunk interfaces.
• Terminal loopback is not supported on routed interfaces.
• You cannot configure SPAN and loopback on the switch at the same time. If you try to configure
SPAN on any port while loopback is configured, you receive an error message.
• If a port is a Flex Link port or belongs to an EtherChannel, it cannot be put into a loopback state. If
loopback is active, you cannot add a port to a Flex Link or EtherChannel.
• Port loopback 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.
Configuring Ethernet Facility Loopback
BEFORE YOU BEGIN
Review the “Enabling Ethernet Loopback” section on page 17-47.
DETAILED STEPS
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Define an interface, and enter interface
configuration mode.
Step 3
ethernet loopback facility [vlan vlan-list]
[mac-address {swap | copy}] [timeout
{seconds | none}] supported
Configure Ethernet facility loopback on the
interface. The keywords have these meanings:
• (Optional) Enter vlan vlan-list to configure
VLAN loopback for nondisruptive loopback
testing. Other VLANs on the port continue to
switch traffic.
• (Optional) Enter mac-address swap to
configure the switch to swap the MAC source
and destination addresses for the loopback
action.
• (Optional) Enter mac-address copy to
configure the switch to copy the MAC source
and destination addresses for the loopback
action. This is the default action if the
mac-address option is not configured.
• (Optional) Enter timeout seconds to set a
loopback timeout period. The range is from 5 to
300 seconds. The default is 60 seconds.
• (Optional) Enter timeout none to set the
loopback to not time out.