![]() There are three (3) protocols defined by CFM: ![]() UP MEPs are commonly used for MAs with a wider reach, such as end-to-end and beyond a single link.DOWN MEPs are typically used for MAs that span a single link.Port MEP - special Down MEP at level zero (0) used to detect faults at the link level (rather than service).CFM PDUs to be responded by the MEP are expected to arrive via the wire connected to the port where the MEP is configured.CFM PDUs generated by the MEP are sent via the wire connected to the port where the MEP is configured.CFM PDUs to be responded by the MEP are expected to arrive via the Bridge's Relay Function.CFM PDUs generated by the MEP are sent towards the Bridge's Relay Function and not via the wire connected to the port where the MEP is configured.Can add, check, and respond to received CFM PDUs.Can be associated per MD and VLAN/EVC (manually or automatically created).Supports the discovery of paths among MEPs and location of faults along those paths.Maintenance Domain Intermediate Point (MIP).Associated per MA and identified by a MEPID (1-8191).Support the detection of connectivity failures between any pair of MEPs in an MA.Maintenance Point - Maintenance End Point Short MA Name Format - Vlan-ID, VPN-ID, integer or string-based.Identified by MAID - "Short MA" Name + MD Name.Defined by a set of Maintenance End Points (MEPs) at the edge of a domain.Monitors connectivity of a particular service instance in a given MD, such as one service that traverses four MDs = four MAs.MD Name Format: null, MAC address, DNS or string-based.Up to eight levels of "nesting": MD Level (0.7) - the higher the level, the broader it's reach.MD may nest and touch, but never intersect.Defined by Operational/Contractual Boundaries, such as Customer/Service Provider/Operator.Protocols (Continuity Check, Loopback, and Linktrace) used for Fault Management activities.Maintenance Points (MPs) that generate and respond to CFM Protocol Data Units (PDUs).Maintenance Associations (MAs) that monitor service instances under a given MD.Nested Maintenance Domains (MDs) that break up the responsibilities for network administration of a given end-to-end service.Standardized by IEEE in 2007 IEEE std.CFM frames are distinguished by Ether-Type (0x8902) and dMAC address (for multicast messages).Devices that cannot interpret CFM Messages forward them as normal data frames.Employs regular Ethernet frames that travel in-band with the customer traffic.Family of protocols that provides capabilities to detect, verify, isolate, and report end-to-end Ethernet connectivity faults.Link OAM - Any point-to-point 802.3 link.E-LMI - User to Network Interface (UNI).OAM functions and mechanisms for Ethernet-based networks - MEF E-LMI (Ethernet Local Management Interface).Ethernet Link OAM (also referred as 802.3 OAM, Link OAM, or Ethernet in the First Mile (EFM) OAM) - ITU-T Y.1731.More importantly, the timeliness to isolate and respond to a failure becomes mandatory for normal day-to-day operations, and OAM translates directly to the competitiveness of the service provider. The expansion of Ethernet technology into the domain of service providers, where networks are substantially larger and more complex than enterprise networks and the user base is wider, makes operational management of link uptime crucial. The advent of Ethernet as a MAN and WAN technology imposes a new set of OAM requirements on Ethernet's traditional operations, which were centered on enterprise networks only. It includes proactive connectivity monitoring, fault verification, and fault isolation for large Ethernet metropolitan-area networks (MANs) and WANs. Background InformationĮthernet CFM is an end-to-end per-service-instance Ethernet layer operation, administration, and management (OAM) protocol. If your network is live, ensure that you understand the potential impact of any command. ![]() All of the devices used in this document started with a cleared (default) configuration. The information in this document was created from the devices in a specific lab environment. This document is not restricted to specific software and hardware versions. Prerequisites RequirementsĬisco recommends that you have knowledge of these topics: This document does not explain hardware limitations or the supported interface for CFM to work. The basic concepts of CFM, CFM's building blocks, a configuration guide, show commands, and Wireshark analysis of CFM messages is provided. This document describes Connectivity Fault Management (CFM) technology, configuration, post-checks, and troubleshooting.
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