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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 57 Configuring Ethernet OAM and CFM Configuring Y.1731 Fault Management

Multicast Ethernet Loopback

The multicast Ethernet loopback (ETH-LB) function verifies bidirectional connectivity of a MEP with
its peer MEPs and is an on-demand OAM function. When the feature is invoked on a MEP by entering
the ping privileged EXEC command, the MEP sends a multicast frame with ETH-LB request
information to peer MEPs in the same MEG. The MEP expects to receive a unicast frame with ETH-LB
reply information from its peer MEPs within a specified time period. A MEP receiving a multicast frame
with ETH-LB request information validates the frame and transmits a frame with reply information.
To configure multicast ETH-LB, you configure the MEG level of the MEP and the priority of the
multicast frames with ETH-LB requests. Multicast frames with ETH-LB request information are always
marked as drop ineligible. No MIP configuration is required.
The MEP sends multicast LB message frames on an on-demand basis. After sending a multicast LBM
frame, the MEP expects to receive LB reply frames within 5 seconds.
When a MEP receives a valid LBM frame, it generates an LB reply frame and sends it to the requested
MEP after a random delay in the range of 0 to 1 second. The validity of the frame is determined on its
having the correct MEG level.
When a MEP sends a multicast LBM frame and receives an LB reply frame within 5 seconds, the LB
reply frame is valid.
Configuring Y.1731 Fault Management
To configure Y.1731 fault management, you must enable CFM and configure MIPs on the participating
interfaces. AIS messages are generated only on interfaces with a configured MIP.
Default Y.1731 Configuration, page 57-29
Configuring ETH-AIS, page 57-29
Using Multicast Ethernet Loopback, page 57-31

Default Y.1731 Configuration

ETH-AIS and ETH-LCK are enabled by default when CFM is enabled.
When you configure ETH-AIS or ETH-LCK, you must configure CFM before ETH-AIS or ETH-LCK
is operational.
ETH-RDI is set automatically when continuity check messages are enabled.

Configuring ETH-AIS

Beginning in privileged EXEC mode, follow these steps to configure Ethernet AIS on a switch:
Command Purpose
Step 1 configure terminal Enters global configuration mode.
Step 2 ethernet cfm ais link-status global Configures AIS-specific SMEP commands by entering
config-ais-link-cfm mode.