Recognizing the
need for delivery guarantees for the SNMP protocol, newer specifications of the aforementioned
mechanism include additional OAMPDUs, effectively creating an acknowledged
transmission path, along with a keep-alive mechanism to ensure the given link
is open and traversable at any time.
Remote Failure Indication Any link faults in Ethernet networks are difficult to
detect and isolate, especially when they are caused by slow decay of link quality rather
than abrupt and typically catastrophic severance. A flag in the OAMPDU data frame
allows any OAM-enabled unit to notify its peers on the link failure conditions, including
during the following situations:
?– Link fault event, occurring when the signal loss state is detected by the receiver.
Such a notification flag is transmitted once per second (only the direct link peer is
notified about this particular condition).
?– Dying gasp event, occurring when an unpredictable external condition, such as a
power failure, occurs, degrading the link transmission capabilities. Such a notification
flag is transmitted immediately after the onset of the event and in a continuous
manner (all link peers are notified about this event).
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