H3C S5120-EI Series - Page 15

6
Item Active Ethernet OAM mode Passive Ethernet OAM mode
Transmitting Event Notification
OAMPDUs
Available Available
Transmitting Information
OAMPDUs without any TLV
Available Available
Transmitting Loopback Control
OAMPDUs
Available Unavailable
Responding to Loopback Control
OAMPDUs
Available—if both sides operate in
active OAM mode
Available
NOTE:
• Only OAM entities operating in active OAM mode can initiate OAM connections. OAM entities
operating in passive mode wait and respond to the connection requests sent by their peers.
• 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 at the handshake packet transmission interval to check whether the Ethernet
OAM connection is normal. 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 is used to detect and
indicate link faults in various environments. Ethernet OAM implements link monitoring through the
exchange of Event Notification OAMPDUs. When detecting one of the link error events listed in Table 7,
the local O
AM entity sends an Event Notification OAMPDU to notify the remote OAM entity. With the
log information, network administrators can keep track of network status promptly.
Table 7 Ethernet OAM link error events
Ethernet OAM link events Descri
p
tion
Errored symbol event
An errored symbol event occurs when the number of detected symbol
errors during a specified detection interval exceeds the predefined
threshold.
Errored frame event
An errored frame event occurs when the number of detected error
frames during a specified interval exceeds the predefined threshold.
Errored frame period event
An errored frame period event occurs if the number of frame errors in
a specific number of received frames exceeds the predefined
threshold.
Errored frame seconds event
An errored frame seconds event occurs when the number of error
frame seconds detected on a port during a specified detection
interval reaches the error threshold.
The system transforms the period of detecting errored frame period events into the maximum number of
64-byte frames (excluding the interframe spacing and preamble) that a port can send in the specified
period. The system takes the maximum number of frames sent as the period. The maximum number of
frames sent is calculated using this formula: the maximum number of frames = interface bandwidth (bps)
× errored frame period event detection period (in ms)/(64 × 8 × 1000).