23.1.3 Design of the domain

To use the CFM functionality, design the domains first. Then design the domain configurations and their hierarchies, and finally design the details of each domain.

When you design a domain, you must configure the domain level, MAs, MEPs, and MIPs.

<Structure of this section>

(1) Configuring Domains and Designing Hierarchical Structures

Set an MA port (for which the MA is the boundary between domains) as a MEP and set a port that overlaps with the lower domain as a MIP. The procedure for designing the domain configuration and the hierarchy is described below according to the configuration example shown in the following figure.

Figure 23-12: Configuration example

Design the domain as units, such as business unit A, business unit B, the overall business unit, and user, and then specify the domain level appropriate for the category. Also, the following items are assumed:

Operator A, Provider The entire B, Provider manages connectivity, including the ports provided to users, to ensure that the lines provided to users are available.
Users manage the connectivity of the line provided by a business unit in order to monitor the availability of that line.

Design a domain from the lowest level up as described below.

- Setting of domain levels 1 and 2

In domain level 1, configure MA "Group_A".

In this example, one domain is managed by one MA. If you want to manage the domain more precisely by subdividing it into VLAN groups, set an MA for each management unit.
Set an MA port as a MEP on switches B and D, which are on the domain boundary.

The business unit configures the up MEPs in order to manage the connectivity, including the ports to be provided to users.

Set an MA for domain level 2 as well, and configure an up MEP on switches E and G.

Figure 23-13: Configuring domain levels 1 and 2

- Configuring Domain Level 4

In domain level 4, configure MA "Group_C".
Set an MA port as a MEP on switches B and G, which are on the boundary of domain level 4.

The business unit configures the up MEPs in order to manage the connectivity, including the ports to be provided to users.

Because domain level 4 contains domain levels 1 and 2, configure MIPs on switches D and E, which are the relay points of each domain level.

If you set a MEP of a lower domain as a MIP in a higher domain, you can identify the scope of investigation more easily because you can use the loopback or linktrace functionality to determine if the problem has occurred in the domain you manage or in a lower-level domain.

Figure 23-14: Configuring domain level 4

- Configuring Domain Level 7

In domain level 7, specify MA "Group_D".
Set an MA port as a MEP on switches A and H, which are on the boundary of domain level 7.

In order to manage the connectivity of the lines provided by business units, users configure the down MEP.

Because domain level 7 contains domain level 4, configure MIPs on switches B and D, which are relay points.

Because domain levels 1 and 2 are specified as relay points of domain level 4, it is not necessary to configure domain levels 1 and 2 in domain level 7.

Figure 23-15: Configuring domain level 7

(2) Detailed design of individual domains

For the detailed design, configure, as MIPs, the points to which you want to apply the loopback functionality and the linktrace functionality.

The following figure shows configuration examples before and after MIPs are set.

Figure 23-16: Sample Configuration Before Setting MIP

Figure 23-17: Sample Configuration After Setting MIP

Inside the domain, specify, as MIPs, the ports to be configured as the destination of the loopback functionality and the linktrace functionality. In this example, MIPs are set on switches B and D. With this configuration, you can perform loopback and linktrace for the MIPs on switches B and D. In addition, routing information of the linktrace functionality is returned as a response.

You cannot specify switch C as the destination for loopback and linktrace because no MIPs are configured on switch C. In addition, because switch C does not respond to the linktrace functionality, information about switch C is not contained in routing information.

(3) Domain Configuration Examples

Domains can be configured hierarchically. The inner part of the hierarchy must be configured as lower-level domains and the outer part as higher-level domains.

The following table provides configuration examples are states whether they are possible or not.

Table 23-4: Domain configuration examples and configurability
Configuration status	Configuration example	Whether configurable
Neighboring domains		Supported
Touching domains		Supported
Nested domains		Supported
Combination of neighboring domains and nested domains		Supported
Overlapping domains		Not supported