1-11 Connectivity Fault Detection ConfigurationWhen configuring CFD, go to these sections for information you are interested in:z Overviewz CFD Configuration Task Listz Basic Configuration Tasksz Configuring CC on MEPsz Configuring LB on MEPsz Configuring LT on MEPsz Displaying and Maintaining CFDz CFD Configuration ExamplesThe S7900E Series Ethernet Switches are distributed devices that support Intelligent ResilientFramework (IRF). Two S7900E series can be connected together to form a distributed IRF device. Forintroduction of IRF, refer to IRF Configuration in the System Volume.OverviewConnectivity Fault Detection (CFD) is an end-to-end per-VLAN link layer Operations, Administrationand Maintenance (OAM) mechanism used for link connectivity detection, fault verification, and faultlocation.Basic Concepts in CFDMaintenance domainA maintenance domain (MD) defines the network where CFD plays its role. The MD boundary is definedby some maintenance association end points MEPs configured on the ports. An MD is identified by anMD name.To locate faults exactly, CFD introduces eight levels (from 0 to 7) to MDs. The bigger the number, thehigher the level and the larger the area covered. Domains can touch or nest (if the outer domain has ahigher level than the nested one) but cannot intersect or overlap.MD levels facilitate fault location and make fault location more accurate. As shown in Figure 1-1, MD_Ain light blue nests MD_B in dark blue. If a connectivity fault is detected at the boundary of MD_A, any ofthe devices in MD_A, including Device A through Device E, may fail. In this case, if a connectivity fault isalso detected at the boundary of MD_B, the failure points may be any of Device B through Device D. Ifthe devices in MD_B operate normally, you can be sure that at least Device C is operational.
