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Configure Ethernet OAM Connectivity Fault Management (CLI Procedure)

Ethernet interfaces on Juniper Networks EX Series Ethernet Switches and Juniper Networks Junos OS for EX Series switches support the IEEE 802.1ag standard for Operation, Administration, and Management (OAM). The IEEE 802.1ag specification provides for Ethernet connectivity fault management (CFM).


This feature is not supported on EX4300 switches on aggregated Ethernet (LAG) interfaces.

This topic describes these tasks:

Creating the Maintenance Domain

A maintenance domain comprises network entities such as operators, providers, and customers. To enable connectivity fault management (CFM) on an Ethernet interface, you must create a maintenance domains, maintenance associations, and MEPs.

To create a maintenance domain:

  1. Specify a name for the maintenance domain:
  2. Specify a format for the maintenance domain name. If you specify none, no name is configured:
    • A plain ASCII character string

    • A domain name service (DNS) format

    • A media access control (MAC) address plus a two-octet identifier in the range 0 through 65,535

    • none

    For example, to specify the name format as MAC address plus a two-octet identifier:

  3. Configure the maintenance domain level, which is used to indicate the nesting relationship between this domain and other domains. Use a value from 0 through 7:

    The configuration display entries in the CFM maintenance domain list are "ordered by system" rather than "ordered by user."

Configuring the Maintenance Domain MIP Half Function


MIP Half Function (MHF) is not supported on EX4600, QFX5200, and QFX5210 switches.

MIP Half Function (MHF) divides the maintenance association intermediate point (MIP) functionality into two unidirectional segments, improves visibility with minimal configuration, and improves network coverage by increasing the number of points that can be monitored. MHF extends monitoring capability by responding to loop-back and link-trace messages to help isolate faults. Whenever a MIP is configured, the MIP half function value for all maintenance domains and maintenance associations must be the same.

To configure the MIP half function:

Creating a Maintenance Association

In a CFM maintenance domain, each service instance is called a maintenance association.

To create a maintenance association:


The configuration display entries in the CFM maintenance domain list are "ordered by system" rather than "ordered by user."

Configuring the Continuity Check Protocol

The continuity check protocol is used for fault detection by a maintenance association end point (MEP) within a maintenance association. The MEP periodically sends continuity check multicast messages. The receiving MEPs use the continuity check messages (CCMs) to build a MEP database of all MEPs in the maintenance association.

To configure the continuity check protocol:

  1. Enable the continuity check protocol:
  2. Specify the continuity check hold interval. The hold interval is the number of minutes to wait before flushing the MEP database if no updates occur. The default value is 10 minutes.
  3. Specify the CCM interval. The interval is the time between the transmission of CCMs. You can specify 10 minutes (10m), 1 minute (1m), 10 seconds (10s), 1 second (1s), 100 milliseconds (100ms), or 10 milliseconds (10ms).

    On EX4600, QFX5200, and QFX5210 switches, CCM interval of less than 1 second is not supported.

  4. Specify the number of CCMs (that is, protocol data units) that can be lost before the MEP is marked as down. The default number of protocol data units (PDUs) is 3.

Configuring a Maintenance Association End Point

To configure a maintenance association end point:

  1. Specify an ID for the MEP. The value can be from 1 through 8191.
  2. Enable maintenance endpoint automatic discovery if you want to have the MEP accept continuity check messages (CCMs) from all remote MEPs of the same maintenance association:
  3. You can specify that CFM packets (CCMs) be transmitted only in one direction for the MEP, that is, the direction be set as down so that CCMs are transmitted only out of (not into) the interface configured on this MEP.
  4. Specify the logical interface to which the MEP is attached. It can be either an access interface or a trunk interface. If you specify a trunk interface, the VLAN associated with that interface must have a VLAN ID.

    You cannot associate an access interface that belongs to multiple VLANs with the MEP.

  5. You can configure a remote MEP from which CCMs are expected. If autodiscovery is not enabled, the remote MEP must be configured under the mep statement. If the remote MEP is not configured under the mep statement, the CCMs from the remote MEP are treated as errors.

Configuring a Connectivity Fault Management Action Profile

You can configure an action profile and specify the action to be taken when any of the configured events occur. Alternatively, you can configure an action profile and specify default actions when connectivity to a remote MEP fails.

To configure an action profile:

  1. Specify a name for an action profile:
  2. Configure the action of the action profile:
  3. Configure one or more events under the action profile, the occurrence of which will trigger the corresponding action to be taken:

Configuring the Linktrace Protocol

The linktrace protocol is used for path discovery between a pair of maintenance points. Linktrace messages are triggered by an administrator using the traceroute command to verify the path between a pair of MEPs under the same maintenance association. Linktrace messages can also be used to verify the path between a MEP and a MIP under the same maintenance domain.

To configure the linktrace protocol:

  1. Configure the linktrace path age timer. If no response to a linktrace request is received, the request and response entries are deleted after the age timer expires:
  2. Configure the number of linktrace reply entries to be stored per linktrace request: