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Hierarchy Level


Configure the interval between successive transmissions of continuity check messages (CCMs) as part of the connectivity fault detection strategy. When the receiving maintenance association end point (MEP) does not receive a CCM at the configured interval, the loss-threshold statement determines how many CCMs can be lost before the sending MEP is marked as down. The hold-interval statement then determines the frequency at which the database of MEPs in the maintenance association (MA) is flushed in the absence of updates.


When the continuity-check interval is set to 3.3ms, the actual interval is 4ms (250 pps).

During a unified in-service software upgrade (ISSU), Junos OS connectivity fault management (CFM) works when the peer device is not a Juniper Networks router. Interoperating with the router of another vendor, the Juniper Networks router retains session information and continues to transmit CCM (continuity check message) PDUs during the unified ISSU upgrade. For this feature to work, you must enable Packet Forwarding Engine keepalives with the hardware-assisted-keepalives statement, and configure the interval between CCMs to be 1 second with interval statement.


For the continuity check message interval to be configured for 10 milliseconds, periodic packet management (PPM) runs on the Routing Engine and Packet Forwarding Engine by default. You can disable PPM only on the Packet Forwarding Engine. To disable PPM on the Packet Forwarding Engine, use the no-delegate-processing statement at the [edit routing-options ppm] hierarchy level.


A continuity check interval of 10 milliseconds is not supported for CFM sessions over a label-switched interface (LSI).


100ms—100 milliseconds.

10m—10 minutes.

10ms—10 milliseconds.

10s—10 seconds.

1m—1 minute.

1s—1 second.

3.3ms—3.3 milliseconds.

  • Default: 1m

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 8.4.

Option 10ms introduced in Junos OS Release 9.1.

Third-party interoperability during a unified in-service software upgrade (ISSU) introduced in Junos OS Release 17.1.

Option 3.3ms introduced in Junos OS Release 17.2.