Figure 33: Relationship of MEPs, MIPs, and MD Levels.
Ethernet interfaces on M320, MX-series, and T-series routing platforms support the IEEE 802.1ag standard for operation, administration, and management (OAM). The IEEE 802.1ag specification provides for Ethernet connectivity-fault management (CFM). The goal of CFM is to monitor an Ethernet network that may be comprised of one or more service instances. JUNOS software supports IEEE 802.1ag connectivity fault management.
Network entities such as operators, providers, and customers may be part of different administrative domains. Each administrative domain is mapped into one maintenance domain (MD). MDs are configured with different level values to keep them separate. Each domain provides enough information for the entities to perform their own management, perform end-to-end monitoring, and still avoid security breaches.
Figure 33 shows the relationships between the customer, provider, and operator Ethernet bridges, MDs, maintenance association end points (MEPs), and maintenance intermediate points (MIPs).
Figure 33: Relationship of MEPs, MIPs, and MD Levels.
A maintenance association (MA) is a set of MEPs configured with the same maintenance association identifier (MAID) and MD level. Figure 34 shows the hierarchical relationships between the Ethernet bridge, MDs, MAs, and MEPs.
Figure 34: Relationship of Bridges, MDs, MAs, and MEPs.
The Continuity Check protocol is used for fault detection by a MEP within an MA. The MEP periodically sends Continuity Check multicast messages. The receiving MEPs use the CC messages to build a MEP database of all MEPs in the MA
To enable CFM on an Ethernet interface, MDs, MAs, and MEPs must be created and configured.
To create an MD, include the maintenance-domain domain-name statement at the [edit protocols oam ethernet connectivity-fault-management] hierarchy level.
Give the MD a name. Names can be in one of several formats.
You can specify the MD name format as plain ASCII character string, domain name service (DNS) format, MAC address plus a two-octet identifier in the range from 0 through 65,535, or none. If none is specified, the maintenance domain name is not used. The default name format is ASCII character string
To configure the MD name format, include the name-format (character-string | none | dns | mac+2octet) statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name] hierarchy level.
The maintenance domain level is a mandatory parameter to indicate the nesting relationship between various maintenance domains. The level is embedded in each of the CFM frames. CFM messages with a given level are processed by MEPs at that same level. For example, the operator domain can be level 0, the provider domain at level 3, and the customer domain at level 7.
To configure the MD level, include the level number statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name] hierarchy level.
To create an MA, include the maintenance-association ma-name statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name] hierarchy level.
Give the MA a name. The names can be in one of several formats.
You can specify the MA short name format as a plain ASCII character string, the VLAN identifier of the VLAN you primarily associate with the MA, a two-octet identifier in the range from 0 through 65,535, or a name in the format specified by RFC 2685. The default short name format is ASCII character string.
To configure the MA short name format, include the short-name-format (character-string | vlan | 2octet | rfc-2685-vpn-id) statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name] hierarchy level.
You can configure continuity check protocol parameters.
To enable the continuity check protocol, include the continuity-check statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name] hierarchy level.
You can 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.
To configure the hold interval include the hold-interval statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name continuity-check] hierarchy level:
You can specify the continuity check message (CCMs) 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), or 100 milliseconds (100ms). The default value is 1 minute.
To configure the interval, include the interval statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name continuity-check] hierarchy level.
You can specify number of continuity check messages that can be lost before marking the MEP as down. The default value is 3PDUs.
To configure the loss threshold, include the loss-threshold statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name continuity-check] hierarchy level.
You can configure an MEP.
To configure the maintenance end point, include the mep mep-id statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name] hierarchy level.
You can Enable the MEP to accept continuity check messages from all remote MEPs of the same MA.
To configure the automatic discovery include the auto-discovery statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id] hierarchy level:
You can specify the direction in which CFM packets are transmitted for the MEP.
Direction up CCMs are transmitted out of every logical interface which is part of the same bridging or vpls instance except for the interface configured on this MEP.
Direction down CCMs are transmitted only out of the interface configured on this MEP.
To configure the direction, include the direction statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id] hierarchy level.
You must specify the interface to which the MEP is attached. It can be an physical interface or logical interface.
To configure the interface, include the interface statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id] hierarchy level.
You can specify the IEEE 802.1 priority bits which are used by continuity check and link trace messages.
To configure the priority, include the priority statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id] hierarchy level.
You can configure a remote MEP from which CCM messages are expected. If auto discovery is not enabled, the remote MEP must be configured under a MEP. If the remote MEP is not configured under a MEP, the CCMs from the remote MEP are treated as errors.
To configure the remote MEP, include the remote-mep statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id] hierarchy level.
You can specify the name of the action profile to use for the remote MEP.
To configure the action profile, include the action-profile profile-name statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id remote-mep mep-id] hierarchy level. The profile must already be defined at the [edit protocols oam ethernet connectivity-fault-management] hierarchy level.
You can create an action profile and configure the action to be taken when connectivity to a remote MEP fails.
To configure the action profile name, include the action-profile statement at the [edit protocols oam ethernet connectivity-fault-management] hierarchy level.
You can configure the action to be taken when connectivity to a remote MEP fails.
To configure the action profile action, include the default-action statement at the [edit protocols oam ethernet connectivity-fault-management maintenance-domain domain-name maintenance-association ma-name mep mep-id remote-mep mep-id action-profile ] hierarchy level.
You can enable the interface down action to be taken when connectivity to a remote MEP fails.
To enable the interface down action, include the interface-down statement at the [edit protocols oam ethernet connectivity-fault-management action-profile profile-name default-action] hierarchy level.