Digisol DG-FS4526E, Management Manual

Page: 445 / 1162

C
HAPTER
15 | Basic Administration Protocols
Connectivity Fault Management
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CLI R
EFERENCES
"CFM Commands" on page 1023
C
OMMAND
U
SAGE
Configuring General Settings
Where domains are nested, an upper-level hierarchical domain must
have a higher maintenance level than the ones it encompasses. The
higher to lower level domain types commonly include entities such as
customer, service provider, and operator.
More than one domain can be configured at the same maintenance
level, but a single domain can only be configured with one maintenance
level.
If MEPs (see "Configuring Maintenance End Points" ) or MAs (see
"Configuring CFM Maintenance Associations" ) are configured for a
domain, they must first be removed before you can remove the
domain.
Maintenance domains are designed to provide a transparent method of
verifying and resolving connectivity problems for end-to-end
connections. By default, these connections run between the domain
service access points (DSAPs) within each MA defined for a domain,
and are manually configured (see "Configuring Maintenance End
Points" ).
In contrast, MIPs are interconnection points that make up all possible
paths between the DSAPs within an MA. MIPs are automatically
generated by the CFM protocol when the MIP Creation Type is set to
“Default” or “Explicit,” and the MIP creation state machine is invoked
(as defined in IEEE 802.1ag). The default option allows MIPs to be
created for all interconnection points within an MA, regardless of the
domain’s level in the maintenance hierarchy (e.g., customer, provider,
or operator). While the explicit option only generates MIPs within an MA
if its associated domain is not at the bottom of the maintenance
hierarchy. This option is used to hide the structure of network at the
lowest domain level.
The diagnostic functions provided by CFM can be used to detect
connectivity failures between any pair of MEPs in an MA. Using MIPs
allows these failures to be isolated to smaller segments of the network.
Allowing the CFM to generate MIPs exposes more of the network
structure to users at higher domain levels, but can speed up the
process of fault detection and recovery. This trade-off should be
carefully considered when designing a CFM maintenance structure.
Also note that while MEPs are active agents which can initiate
consistency check messages (CCMs), transmit loop back or link trace
messages, and maintain the local CCM database, MIPs, on the other
hand, are passive agents which can only validate received CFM
messages, and respond to loop back and link trace messages.