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You can monitor frame and symbol errors by setting up a monitoring period or
window and a threshold value. If the number of errors observed during the window
meets or exceeds the configured low threshold, an Event Notification PDU (in the
appropriate TLVs) is generated and sent to the peer. Alternatively, if you configure
a high threshold value on the local OAM peer, the OAM function attempts to alter
the operational state of the link whenever the high threshold value is exceeded. The
monitoring of the link continues with a new window or period as long as the
operational state of the link is up. When the number of errors observed during the
window equals or goes below the configured low threshold value, the OAM application
attempts to reverse the operational state of the link to up.
Supported Error Events for Tracking Link Faults
The OAM application maintains an updated cumulative count of frame and symbol
errors and also an updated summation of events generated as a result of a threshold
exception. Both these sums are displayed in the appropriate link event TLVs and in
the output of the show ethernet oam commands.
Because certain MAC devices on the IOAs might not support a symbol error statistic,
enabling the monitoring of symbol errors is benign and no events are raised for that
link.
The following error events are supported for configuration on Ethernet interfaces:
Because IEEE 802.3ah OAM does not provide a guaranteed delivery of any OAM
PDU, the event notification OAM PDU might be sent multiple times to reduce the
probability of a lost notification. A sequence number is used to distinguish among
duplicate events.
Actions Performed on Exceeding Threshold Values
You can configure the OAM application to influence the operational state of the link,
when a link quality threshold is exceeded or a critical event PDU is received from
the peer, or both. You can configure either of the following actions to be taken when
a high threshold value is exceeded or when a failure condition is communicated by
the remote peer:
Error Symbol Period (error symbols per second) The number of symbol errors
that occurred during a specified period exceeded a threshold. These errors are
coding symbol errors.
Error Frame (error frames per second) The number of frame errors observed
during a specified period exceeded a threshold.
Error Frame Seconds Summary (error seconds per n seconds) The number of
error seconds (1-second intervals with at least one frame error) within the last
n seconds has exceeded a threshold.
Disable OAM unconditionally attempts to influence the operational state of the
interface to down. If the interface is a member link of a LAG bundle and at least
one other viable link (redundant member or another active/up link) is present,
OAM attempts to influence the operational state of the link to down. Otherwise,
no action is taken.
Chapter 7: Configuring IEEE 802.3ah OAM Link-Fault Management
OAM Link Monitoring Feature
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