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Ethernet Failure Notification Protocol Overview

The Failure Notification Protocol (FNP) is a failure notification mechanism that detects failures in Point-to-Point Ethernet transport networks on MX Series routers. If a node link fails, FNP detects the failure and sends out FNP messages to the adjacent nodes that a circuit is down. Upon receiving the FNP message, nodes can redirect traffic to the protection circuit.

Note: FNP is supported on E-Line services only.

An E-Line service provides a secure Point-to-Point Ethernet connectivity between two user network interfaces (UNIs). E-Line services are a protected service and each service has a working circuit and protection circuit. CFM is used to monitor the working and protect paths. CCM intervals result in failover time in hundreds of milliseconds or a few seconds. FNP provides service circuit failure detection and propagation in less than 50ms and provide 50ms failover for E-Line services.

The MX router acts as a PE node and handles the FNP messages received on the management VLAN and the FNP messages received on both the Ethernet interfaces and PWs created for the management VPLS. MX-series routers do not initiate FNP messages and responds only to FNP messages generated by devices in the Ethernet Access network. FNP can be enabled only on logical interfaces that are part of a VPLS routing instance, and no physical interfaces in that VPLS routing instance should have CCM configured. FNP can be enabled only on one logical interface per physical interface.

All E-Line services are configured as layer 2 circuits with edge protection. A VLAN associated with the working circuit or protection circuit must map to a logical interface. No trunk port or access port is supported in the ring link for VLANs used by E-LINE services. FNP does not control the logical interface associated with protection circuit. Only E-Line service whose termination point is not in an MX node is controlled by FNP.

FNP supports graceful restart and the Graceful Routing Engine switchover (GRES) features.

Published: 2012-12-11