Configure Link Fault Management

When the IEEE 802.3ah OAM protocol is enabled on a physical interface, the discovery process is automatically triggered. The discovery process permits Ethernet interfaces to discover and monitor the peer on the link if it also supports the IEEE 802.3ah standard.

You can specify the discovery mode used for IEEE 802.3ah OAM support. The discovery process is triggered automatically when OAM IEEE 802.3ah functionality is enabled on a port. Link monitoring is done when the interface sends periodic OAM PDUs.

To configure the discovery mode, include the link-discovery statement at the [edit protocol oam ethernet link-fault-management interface interface-name] hierarchy level:

In active mode, the interface discovers and monitors the peer on the link if the peer also supports IEEE 802.3ah OAM functionality. In passive mode, the peer initiates the discovery process. After the discovery process has been initiated, both sides participate in discovery.

Periodic OAM PDUs are sent to perform link monitoring.

You can specify the periodic OAM PDU sending interval for fault detection.

To configure the sending interval, include the pdu-interval statement at the [edit protocol oam ethernet link-fault-management interface interface-name] hierarchy level:

The periodic OAM PDU interval range is from 100 through 1000 milliseconds. The default sending interval is 1000 milliseconds.

You can specify the number of OAM PDUs that an interface can miss before the link between peers is considered down.

To configure the number of PDUs that can be missed from the peer, include the pdu-threshold statement at the [edit protocol oam ethernet link-fault-management interface interface-name] hierarchy level:

The threshold value range is from 3 through 10. The default is three PDUs.

You can configure threshold values on an interface for the local errors that trigger the sending of link event TLVs.

To set the error threshold values for sending event TLVs, include the frame-error, frame-period, frame-period-summary, and symbol-period statements at the [edit protocols oam ethernet link-fault-management interface interface-name event-thresholds] hierarchy level:

You can disable the sending of link event TLVs.

To disable the monitoring and sending of PDUs containing link event TLVs in periodic PDUs, include the no-allow-link-events statement at the [edit protocols oam ethernet link-fault-management interface interface-name negotiation-options] hierarchy level:

You can create an action profile to define event fault flags and thresholds and the action to be taken. You can then apply the action profile to one or more interfaces.

To configure an action profile, include the action-profile statement at the [edit protocols oam ethernet link-fault-management] hierarchy level:

You can specify the action to be taken by the system when the configured link-fault event occurs. Multiple action profiles can be applied to a single interface. For each action-profile, at least one event and one action must be specified. The actions are taken only when all of the events in the action profile are true. If more than one action is specified, all the actions are executed.

You might want to set a lower threshold for a specific action such as logging the error and set a higher threshold for another action such as sending a critical event TLV.

To specify the action, include the action statement at the [edit protocols oam ethernet link-fault-management action-profile profile-name] hierarchy level:

To create a system log entry when the link-fault event occurs, include the syslog statement.

To administratively disable the link when the link-fault event occurs, include the link-down statement.

To send IEEE 802.3ah link event TLVs in the OAM PDU when a link-fault event occurs, include the send-critical-event statement.

You can specify actions be taken when link adjacency is lost. When link adjacency is lost, the system takes the action defined in the action statement of the action profile.

To configure the system to take action when link adjacency is lost, include the link-adjacency-loss statement at the [edit protocols oam ethernet link-fault-management action-profile profile-name event] hierarchy level:

The CCC-DOWN flag is associated with a circuit cross-connect (CCC) connection, Layer 2 circuit, and Layer 2 VPN, which send the CCC-DOWN status to the kernel. The CCC-DOWN flag indicates that the CCC is down. The CCC-DOWN status is sent to the kernel when the CCC connection, Layer 2 circuit, or Layer 2 VPN is down. This in turn, brings down the CE-facing PE interface associated with the CCC connection, Layer 2 circuit, or Layer 2 VPN.

When the CCC-DOWN flag is signaled to the IEEE 802.3ah protocol, the system takes the action defined in the action statement of the action profile. For additional information about Layer 2 circuits, see the Junos OS Layer 2 Circuits User Guide, Junos OS VPNs Configuration Guide.

To monitor the IEEE 802.3ah protocol, on the CE-facing PE interface, include the protocol-down statement at the [edit protocols oam ethernet link-fault-management action-profile profile-name event] hierarchy level:

You can configure link event thresholds for received error events that trigger the action specified in the action statement. You can then apply the action profile to one or more interfaces.

To configure link event thresholds, include the link-event-rate statement at the [edit protocols oam ethernet link-fault-management action-profile profile-name event] hierarchy level:

You can apply an action profile to one or more interfaces.

To apply an action profile to an interface, include the apply-action-profile statement at the [edit protocols oam ethernet link-fault-management action-profile interface interface-name] hierarchy level: