Operation Manual

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Remote Failure Indication
Faults in Ethernet are difficult to detect, especially when the physical connection in the network
is not interrupted but network performance degrades gradually. A flag in the OAMPDU allows
an OAM entity to convey failure conditions to its peer. The failure conditions are as follows:
 Link Fault: Peer link signal is lost. This is sent once per second in the Information OAMPDU.
 Dying Gasp: An unrecoverable fault, such as power failure, occurs. This is sent immediately
and continuously.
 Critical Event: Unspecified critical event occurs. This is sent immediately and continuously.
As
Information OAMPDUs are sent between the OAM entities periodically, an OAM entity can
inform one of its OAM peers of link faults through Information OAMPDUs. So the network
administrator can get informed of the link faults and take action in time.
Remote Loopback
Remote loopback helps to ensure the quality of links during installation or when
troubleshooting. After the OAM connection is established, the active OAM entity can put its
OAM peer into loopback mode using a loopback control OAMPDU.
With remote loopback enabled, the active OAM entity sends remote loopback requests and
the peer responds. If the peer is in the loopback mode, it returns all frames except OAMPDUs
and pause frames to the senders along the original paths. Through these return frames,
administrators can test the link performance like delay, jitter, and frame loss rate.
The following figure shows how remote loopback testing works.
Figure 8-3 Remote Loopback