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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 75 Configuring Ethernet OAM and CFM
About Ethernet CFM
CFM Domain
A CFM maintenance domain is a management space on a network that is owned and operated by a single
entity and defined by a set of internal boundary ports. You assign a unique maintenance level (from 0 to
7) to define the domain hierarchy. The larger the domain, the higher the level. For example, as shown in
Figure 75-1, a service-provider domain would be larger than an operator domain and might have a
maintenance level of 6, while the operator domain maintenance level would be 3 or 4.
As shown in Figure 75-2, domains cannot intersect or overlap because that would require management
by more than one entity, which is not allowed. Domains can touch or nest (if the outer domain has a
higher maintenance level than the nested domain). Nesting domains can be useful when a service
provider contracts with one or more operators to provide Ethernet service. Each operator has its own
maintenance domain and the service provider domain is a superset of the operator domains. Maintenance
levels of nesting domains should be communicated among the administrating organizations. CFM
exchanges messages and performs operations on a per-domain basis.
Figure 75-1 CFM Maintenance Domains
Figure 75-2 Allowed Domain Relationships
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Operator 1
PE 1E 1 CE 2PE 2 PE 3 PE 4
Operator 2
MEP
Level 6 Level 6
Level 4
Level 3
MEP MEP
MIP
MIP MIP
MEP MEPMIP MIP
MIP MEP
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Scenario A:
Touching Domains OK
Scenario B:
Nested Domains OK
Scenario C:
Intersecting Domains
Not Allowed
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