Web Management Guide-R04

Table Of Contents
Chapter 13
| Basic Administration Protocols
Connectivity Fault Management
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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.
The MIP creation method defined for an MA (see "Configuring CFM
Maintenance Associations") takes precedence over the method defined on the
CFM Domain List.
Configuring Fault Notification
A fault alarm can generate an SNMP notification. It is issued when the MEP fault
notification generator state machine detects that the configured time period
(MEP Fault Notify Alarm Time) has passed with one or more defects indicated,
and fault alarms are enabled at or above the specified priority level (MEP Fault
Notify Lowest Priority). The state machine transmits no further fault alarms until
it is reset by the passage of a configured time period (MEP Fault Notify Reset
Time) without a defect indication. The normal procedure upon receiving a fault
alarm is to inspect the reporting MEPs managed objects using an appropriate
SNMP software tool, diagnose the fault, correct it, re-examine the MEP’s
managed objects to see whether the MEP fault notification generator state
machine has been reset, and repeat those steps until the fault is resolved.
Only the highest priority defect currently detected is reported in the fault
alarm.
Priority levels include the following options:
Table 37: Remote MEP Priority Levels
Priority Level Level Name Description
1allDefAll defects.
2 macRemErrXcon DefMACstatus, DefRemoteCCM, DefErrorCCM, or
DefXconCCM.
3 remErrXcon DefErrorCCM, DefXconCCM or DefRemoteCCM.
4 errXcon DefErrorCCM or DefXconCCM.