HP 5900 Series Configuration Manual page 8

Ethernet OAM connection establishment
Ethernet OAM connection is the basis of all the other Ethernet OAM functions. OAM connection
establishment is also known as the "Discovery phase," where an Ethernet OAM entity discovers the
remote OAM entity to establish a session.
In this phase, two connected OAM entities exchange Information OAMPDUs to advertise their OAM
configuration and capabilities to each other for a comparison. If their Loopback, link detection, and link
event settings match, the OAM entities establish an OAM connection.
An OAM entity operates in active mode or passive mode. OAM entities in active mode initiate OAM
connections, and OAM entities in passive mode wait and respond to the OAM connection requests. To
set up an OAM connection between two OAM entities, you must set at least one entity to operate in
active mode.
Table 2 shows the actions that a device can perform in different modes.
Table 2 Active Ethernet OAM mode and passive Ethernet OAM mode
Item
Initiating OAM Discovery
Responding to OAM Discovery
Transmitting Information
OAMPDUs
Transmitting Event Notification
OAMPDUs
Transmitting Information
OAMPDUs without any TLV
Transmitting Loopback Control
OAMPDUs
Responding to Loopback Control
OAMPDUs
After an Ethernet OAM connection is established, the Ethernet OAM entities exchange Information
OAMPDUs at the handshake packet transmission interval to detect the availability of the Ethernet OAM
connection. If an Ethernet OAM entity receives no Information OAMPDU within the Ethernet OAM
connection timeout time, the Ethernet OAM connection is considered disconnected.
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 detects link faults in various environments. Ethernet OAM entities monitor link status by
exchanging Event Notification OAMPDUs. When detecting one of the link error events listed in
an OAM entity sends an Event Notification OAMPDU to its peer OAM entity. The network administrator
can keep track of network status changes by retrieving the log.
Table 3 Ethernet OAM link error events
Ethernet OAM link events
Errored symbol event
Active Ethernet OAM mode
Available
Available
Available
Available
Available
Available
Available when both sides are
operating in active OAM mode
Description
An errored symbol event occurs when the number of detected symbol errors
in the detection window (specified number of received symbols) exceeds the
predefined threshold.
2
Passive Ethernet OAM mode
Unavailable
Available
Available
Available
Available
Unavailable
Available
Table 3,