80 | 802.1agw w w . d e l l . c o m | s u p p o r t . d e l l . c o m There is a need for Layer 2 equivalents to manage and troubleshoot native Layer 2 Ethernet networks. Withthese tools, you can identify, isolate, and repair faults quickly and easily, which reduces operational cost ofrunning the network. OAM also increases availability and reduces mean time to recovery, which allows fortighter service level agreements, resulting in increased revenue for the service provider.In addition to providing end-to-end OAM in native Layer 2 Ethernet Service Provider/Metro networks,you can also use CFM to manage and troubleshoot any Layer 2 network including enterprise, datacenter,and cluster networks.Maintenance DomainsConnectivity Fault Management (CFM) divides a network into hierarchical maintenance domains, asshown in Figure 5-1.A CFM maintenance domain is a management space on a network that is owned and operated by a singlemanagement entity. The network administrator assigns a unique maintenance level (0 to 7) to each domainto define the hierarchical relationship between domains. Domains can touch or nest but cannot overlap orintersect as that would require management by multiple entities.Figure 5-1. OAM DomainsMaintenance PointsDomains are comprised of logical entities called Maintenance Points. A maintenance point is an interfacedemarcation that confines CFM frames to a domain. There are two types of maintenance points:• Maintenance End Points (MEPs): a logical entity that marks the end-point of a domain• Maintenance Intermediate Points (MIPs): a logical entity configured at a port of a switch that is anintermediate point of a Maintenance Entity (ME). An ME is a point-to-point relationship between twoMEPs within a single domain. MIPs are internal to a domain, not at the boundary, and respond to CFMonly when triggered by linktrace and loopback messages. MIPs can be configured to snoop ContinuityCheck Messages (CCMs) to build a MIP CCM database.Ethernet Access MPLS Core MPLS AccessCustomer NetworkCustomer NetworkCustomer Domain (7)Provider Domain (6)Operator Domain (5)Operator Domain (5)Operator Domain (5)MPLS Domain (4)Service Provider Network
