H3C Technologies H3C S12500 Series Switches - Manual (Page 22)

11
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. On detecting one of the link error events listed in Table 7 , 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 promptly.
Table 7 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 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 when the number of frame errors in
the specified 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 interval reaches the error
threshold.
NOTE:
•
The system transforms the period of detecting errored frame period events into the maximum number of
64-byte frames (excluding interframe spacing and preamble) that a port can send in the specified
period, that is, 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)
• A second in which errored frames appear is called an "errored frame second."
Remote fault detection
Information OAMPDUs are exchanged periodically among Ethernet OAM entities across established
OAM connections. In a network where traffic is interrupted due to device failures or unavailability, the
flag field defined in information OAMPDUs allows an Ethernet OAM entity to send error information (the
critical link event type) to its peer. You can use the log information to track ongoing link status and
troubleshoot problems promptly. Table 8 lists critical link events and the transmission frequencies of the
corresponding OAMPDUs.
Table 8 Critical link events
Type Description
OAMPDU transmission
frequencies
Link Fault Peer link signal is lost. Once per second
Dying Gasp
An unexpected error, such as
power failure, occurred.
Non-stop
Critical event
An undetermined critical event
occurred.
Non-stop