Configure Connectivity Fault Management (CFM)

Maintenance Intermediate Point (MIP) provides monitoring capability of intermediate points for services such as Layer 2 bridging, Layer 2 circuit, and Layer 2 VPN. ACX5048 and ACX5096 routers support MIPs for the Ethernet OAM 802.1ag CFM protocol. Use the bridge-domain, interface, and mip-half-function MIP options to specify the MIP configuration.

To display MIP configurations, use the show oam ethernet connectivity-fault-management mip (bridge-domain | instance-name | interface-name) command.

The following MIP configurations are supported in ACX5048 and ACX5096 routers:

• MIP with with bridge domain

• MIP with circuit cross-connect (CCC)

• MIP with bridge domain when maintenance association end point is configured

• MIP with CCC when maintenance association end point is configured

The following sections describe MIP configuration:

• Configure the Maintenance Domain Bridge Domain
• Configure the Maintenance Domain MIP Half Function
• Configure the Maintenance Association Intermediate Points with Bridge Domain
• Configure the Maintenance Association Intermediate Points with Circuit Cross-Connect
• Configure the Maintenance Association Intermediate Points with Bridge Domain when Maintenance Association End Point is Configured
• Configure the Maintenance Intermediate Points with Circuit Cross-Connect when Maintenance Association End Point is Configured

The following list describes the continuity check protocol parameters you can configure:

• interval—Frequency of the continuity check messages (CCM) i.e time between the transmission of the CCM messages. You can specify 10 minutes (10m), 1 minute (1m), 10 seconds (10s), 1 second (1s), 100 milliseconds (100ms), or 10 milliseconds (10ms). The default value is 1 minute. For instance, if you specify the interval as 1 minute, the MEP sends the continuity check messages every minute to the receiving MEP.

  Note:

  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 only disable PPM 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.

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

• hold-interval—Frequency at which the MEP database can be flushed, if no updates occur. Receiving MEPs use the continuity check messages to build a MEP database of all MEPs in the maintenance association. The frequency is the number of minutes to wait before flushing the MEP database if no updates occur. The default value is 10 minutes.

  Note:

  Hold timer based flushing is applicable only for autodiscovered remote MEPs and not for statically configured remote MEPs.

  The hold interval logic runs a polling timer per CFM session level (not per remote MEP level) where the polling timer duration is equal to the configured hold time. When the polling timer expires, it deletes all the autodiscovered remote MEP entries which have been in the failed state for a time period equal to or greater than the configured hold time. If the remote MEP completes the hold time duration in the failed state, then flushing will not occur until the next polling timer expires. Hence remote MEP flushing may not happen exactly at the configured hold time.

• loss-threshold—Number of continuity check messages that can be lost before the router marks the MEP as down. The value can be from 3 to 256 protocol data units (PDUs). The default value is 3 PDUs.

Junos OS release 16.1R1 and later supports performance monitoring that is compliant with Technical Specification MEF 36. Technical Specification MEF 36 specifies the performance monitoring MIB. The performance monitoring MIB is required to manage service operations, administration, and maintenance (OAM) implementations that satisfy the Service OAM requirements and framework specified in MEF 17 and MEF 35, the management objects specified in MEF 7.1, and the performance monitoring functions defined in ITU-T Y.1731 and IEEE 802.1ag.

You can enable MEF-36-compliant performance monitoring by configuring the measurement-interval statement at the [edit protocols oam ethernet cfm performance-monitoring] hierarchy level.

When MEF-36-compliant performance monitoring is enabled:

• An SNMP get next request for a variable might not fetch the current value unless an SNMP walk is performed before performing the get next request. This limitation applies only to the current statistics for delay measurement, loss measurement, and synthetic loss measurement.

• The output for the field Current delay measurement statistics might display a measurement interval of 0 (zero) and an incorrect timestamp until the first cycle time has expired.

• Supported data TLV size for performance monitoring protocol data units (PDUs) is 1386 bytes when MEF-36-compliant performance monitoring is enabled. The TLV size is 1400 bytes in legacy mode.

• The maximum configurable value for the lower threshold bin is 4,294,967,294.

• Frame loss ratio (FLR) is excluded in loss measurements during period of unavailability for synthetic loss measurement only. In case of loss measurement, FLR is included even during period of unavailability.

• During a period of loss of continuity (adjacency down), although SOAM PDUs are not sent, FLR and availability calculations are not stopped. These calculations are performed with the assumption of 100% loss.

• The number of SOAM PDUs that are sent during the first measurement interval might be less than expected. This is because of a delay in detecting the adjacency state at the performance monitoring session level.

• The number of SOAM PDUs transmitted during a measurement interval for a cycle time of 100 ms might not be accurate. For example, in a measurement interval of two minutes with a cycle time 100 ms, the SOAM PDUs transmitted might be in the range of 1198—2000.

Damping limits the number of jnxSoamPmThresholdCrossingAlarm traps sent to the NMS by summarizing the flap occurrences over a period of time, known as the flap trap timer, and sends a single jnxSoamPmThresholdFlapAlarm notification to the NMS. You can configure the duration of the flap trap timer to any value from 1 through 360 seconds.

The jnxSoamPmThresholdFlapAlarm notification is generated and sent when the following conditions are met:

• At least one flap has occurred when the flap timer has expired.

• You changed the value of the flap trap timer, which caused the timer to stop.

You can enable damping at the global level for the iterator or you can enable damping at the individual threshold type of the iterator. For instance, to enable damping at the global level, for the iterator, use the following command: set protocols oam ethernet cfm performance-monitoring sla-iterator-profiles profile-name flap-trap-monitor. To enable damping at a specific threshold type, for the avg-fd-twoway-threshold, use the following command: set protocols oam ethernet cfm performance-monitoring sla-iterator-profiles profile-name avg-fdv-twoway-threshold flap-trap-monitor.

You can also disable damping.