IEEE 802.1ag OAM Connectivity Fault Management Overview
Ethernet interfaces on M7i and M10i routers with the Enhanced Forwarding Engine Board and on M120, M320, MX Series, and T Series routers 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 comprise one or more service instances. Junos OS 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. Maintenance domains 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.
 | Note: As a requirement for Ethernet OAM 802.1ag to work, distributed periodic packet management (PPM) runs on the Routing Engine and Packet Forwarding Engine (PFE) by default. You can only disable PPM on the PFE. To disable PPM on the PFE, include the ppm <no-delegate-processing> statement at the [edit routing-options ppm] hierarchy level. |
IEEE 802.1ag OAM supports graceful Routing Engine switchover (GRES). IEEE 802.1ag OAM is supported on untagged, single tagged, and stacked VLAN interfaces.
Connectivity Fault Management Key Elements
Figure 1 shows the relationships among the customer, provider, and operator Ethernet bridges, maintenance domains, maintenance association end points (MEPs), and maintenance intermediate points (MIPs).
Figure 1: Relationship Among MEPs, MIPs, and Maintenance Domain Levels
A maintenance association is a set of MEPs configured with the same maintenance association identifier and maintenance domain level. Figure 2 shows the hierarchical relationships between the Ethernet bridge, maintenance domains, maintenance associations, and MEPs.
Figure 2: Relationship Among Bridges, Maintenance Domains, Maintenance Associations, and MEPs
