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CLI-based Configuration Guide - Reliability

AR100-S, AR110-S, AR120-S, AR150-S, AR160-S, AR200-S, AR1200-S, AR2200-S, and AR3200-S V200R009

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Overview of CFM

Overview of CFM

CFM defines Operation, Administration, and Maintenance (OAM) functions and provides link connectivity detection.

Easy-to-use Ethernet techniques support good bandwidth extensibility on low-cost hardware. With these advantages, Ethernet services and structures are the first choice for many enterprise networks, Metropolitan Area Networks (MANs), and wide area network (WANs). The increasing popularity of Ethernet applications promotes the use of Ethernet OAM functions because traditional Ethernet has poor maintainability and operability.

Hierarchical Ethernet OAM needs to be provided based on the network architecture, as shown in Figure 9-1.

Figure 9-1  Networking of Ethernet OAM

  • IEEE 802.3ah, also known as Ethernet in the First Mile (EFM), is a link-level OAM mechanism that defines the specifications of the Ethernet physical layer and OAM used for user access. It provides link connectivity detection, link fault monitoring, remote fault notification, and remote loopback for a link between two directly connected devices.

  • IEEE 802.1ag, also known as Connectivity Fault Management (CFM), defines OAM functions, including Continuity Check (CC), Loopback (LB), and Linktrace (LT). CFM is network-level OAM and is applicable to large-scale end-to-end networking.

  • Y.1731 is an OAM protocol defined by the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T). It covers items defined in IEEE 802.1ag and provides additional OAM messages for fault management and performance monitoring. Fault management includes alarm indication signal (AIS), remote defect indication (RDI), locked signal (LCK), test signal, automatic protection switching (APS), maintenance communication channel (MCC), experimental (EXP) OAM, and vendor specific (VSP) OAM. Performance monitoring includes frame loss measurement (LM) and delay measurement (DM).

Updated: 2019-05-17

Document ID: EDOC1000174116

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