Raisecom ISCOM2600G-HI (A) Series Configuration Manual page 394

Raisecom
ISCOM2600G-HI (A) Series Configuration Guide
OAM discovery
The Ethernet OAM connection process is the OAM discovery phase, where an OAM entity
discovers a remote OAM entity and establishes a session with it.
This phase is initiated by an OAM entity that is in active mode. One ends informs the other of
its Ethernet OAM configurations and Ethernet OAM capabilities supported by the local node
by exchanging OAM PDU. Both ends determine whether to establish OAM connection. If yes,
Ethernet OAM protocol will work on the link layer.
Only the OAM entity in active mode can initiate OAM connection.
After the OAM connection is established, both ends keep connected by exchanging OAM
PDU. If one end fails to receive OAM PDU within the timeout time, it believes that
connection expires and reconnection is required.
Monitoring link
In the OAM connection, an OAM entity keeps sending Information OAM PDUs. The local
OAM entity can inform the peer OAM entity of threshold events through Information OAM
PDUs. In this way, the network administrator can learn the link state and take actions
accordingly.
The network administrator monitors Ethernet OAM through the Event Notification OAM
PDU. When a link fails, the passive OAM entity detects the failure, and actively sends Event
Notification OAM PDU to the peer active OAM entity to inform the following threshold
events. By default, 3 Dying Gasp Traps are sent. Therefore, the network administrator can
dynamically master the network status through the link monitoring process.
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Informing of peer fault
When a device is faulty or fails, it may cause network failure. Thus a flag is defined in OAM
PDU packet to allow an OAM entity to transmit fault information to the peer. The flag may
stand for the following threshold events:
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Remote loopback
Remote loopback is used to locate the area with the fault and help you test link quality with
instruments. Periodical loop detection helps you find network faults in time and segmental
loop detection helps you locate the specified area with the fault and clear the fault.
Error frame event: the number of error frames exceeds the threshold in a time unit.
Error frame period event: the number of error frames exceeds the threshold in a period
(specified N frames).
Error frame second event: the number of error frames in M seconds exceeds the
threshold. The second when an errored frame is generated is called the errored frame
second.
Error symbol period event: the number of error symbols received in a period (monitor
window) exceeds the threshold.
Link fault: signals from the peer are lost. OAM PDUs are sent every 1s.
Dying gasp: an unpredictable event occurs which causes the system to be irrevocable,
such as power failure. In this case, OAM PDUs are sent ceaselessly.
Critical event: an uncertain critical event occurs, such as abnormal temperature. In this
case, OAM PDUs are sent ceaselessly,
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