3Com S7902E, Configuration Manual

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1-4
Item Active Ethernet OAM mode Passive Ethernet OAM mode
Responding to Loopback
Control OAMPDUs Available (if both sides operate
in active OAM mode)
Available
z
OAM connections can be initiated only by OAM entities operating in active OAM mode, while those
operating in passive mode wait and respond to the connection requests sent by their peers.
z
No OAM connection can be established between OAM entities operating in passive OAM mode.
After an Ethernet OAM connection is established, the Ethernet OAM entities on both sides exchange
Information OAMPDUs periodically to keep the Ethernet OAM connection valid. If an Ethernet OAM
entity receives no Information OAMPDU for five seconds, the Ethernet OAM connection is
disconnected.
The interval to send Information OAMPDUs is determined by a timer. Up to ten Information OAMPDUs
can be sent in a second.
Link monitoring
Error detection in an Ethernet is difficult, especially when the physical connection in the network is not
disconnected but network performance is degrading gradually. Link monitoring is used to detect and
indicate link faults in various environments. Ethernet OAM implements link monitoring through the
exchange of Event Notification OAMPDUs. Upon detecting a link error event listed in Table 1-4 , the
local OAM entity sends an Event Notification OAMPDU to notify the remote OAM entity. With the log
information, network administrators can keep track of network status in time. Table 1-4 describes the
link events.
Table 1-4 Ethernet OAM link error events
Ethernet OAM link events Description
Errored symbol event
An errored symbol event occurs when the
number of detected symbol errors over a specific
detection interval exceeds the predefined
threshold.
Errored frame event
An errored frame event occurs when the number
of detected error frames over a specific interval
exceeds the predefined threshold.
Errored frame period event
An errored frame period event occurs if the
number of frame errors in specific number of
received frames exceeds the predefined
threshold.