Foundry NetIron M2404C and M2404F Metro Access Switches
Network Administration Tools (Rev. 03)
802.1ag Connectivity Fault Management (CFM)
© 2008 Foundry Networks, Inc.
Page 85 of 155
Figure 17: Link Trace Operation
Fault Notification and Alarm Suppression (Fault Alarms)
A Fault Alarm is a Management operation, typically a SNMP Notification to a designated address.
It is issued when the MEP detects that a configured time period (default value is 3.5 seconds) has
passed with one or more defects indicated, and Fault Alarms are enabled. The MEP can transmit no
further Fault Alarms until a configured time period (default value is10 seconds) has passed during
which no defect indication is present.
A number of separate defects are maintained by a MEP. For example, there is one for defects that
could be caused by the accidental cross-connection of two different MAs, and one for defects that
are confined to a single MA. The defects are ranked by priority. If a higher priority defect occurs
after a lower priority defect has triggered a Fault Alarm, then the MEP will transmit another Fault
Alarm. This enables the operator to reliably prioritize Fault Alarms. For example, cross-connect
errors are typically of greater concern in a Service Provider environment than loss of connectivity
errors. Only the highest-priority defect is reported in the Fault Alarm.
In the order of their priority the defects are:
•
DefRDICCM
: The last CCM received by this MEP from some remote MEP contained the
RDI bit;
•
DefMACstatus
: The last CCM received by this MEP from some remote MEP indicated
that the transmitting MEP associated MAC is reporting an error status;
•
DefRemoteCCM
: This MEP is not receiving CCMs from some other MEP in its
configured list;
•
DefErrorCCM
: This MEP is receiving invalid CCMs;
•
DefXconCCM
: This MEP is receiving CCMs that could be from some other MA.
NOTE
Due to yet undefined way to interact with SNMP this is not implemented.