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Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 2 Configuring Interfaces
Information About Interfaces
The port guard feature gives the SAN administrator the ability to prevent this issue from occurring in
environments that are vulnerable to these problems. The port can be configured to stay down after the
first failure or after a specified number of failures in a specified time period. This allows the SAN
administrator to intervene and control the recovery, avoiding any problems caused by the cycling.
Using the port guard feature, you can restrict the number of error reports and bring a malfunctioning port
to down state dynamically. A port can be configured to go into error-disabled state for specific types of
failures.
A general link failure caused by link-down is the superset of all other causes. The sum of the number of
all other causes equals to the number of link-down link failures. This means a port is brought to down
state when it reaches the maximum number of allowed link failures or the number of specific causes.
The causes of link failure can be any of the following:
• ESP trustsec-violation
• Bit-errors
• Signal loss
• Sync loss
• Link reset
• Credit loss
• Additional causes might be the following:
–
Not operational (NOS).
–
Too many interrupts.
–
Cable is disconnected.
–
Hardware recoverable errors.
–
The connected device rebooted (F ports only).
–
The connected linecard rebooted (ISL only).
Port Monitor
Port monitor helps to monitor the performance and the status of ports and generate alerts when problems
occur. You can configure the thresholds for various counters and trigger an event when the values cross
the threshold settings.
The default port monitor policy has the following threshold values:
Counter
Threshold
Type
Interval
(Seconds)
% Rising
Threshold
Event
% Falling
Threshold
Event
Link Loss Delta 60 5 4 1 4
Sync Loss Delta 60 5 4 1 4
Protocol Error Delta 60 1 4 0 4
Signal Loss Delta 60 5 4 1 4
Invalid Words Delta 60 1 4 0 4
Invalid CRCs Delta 60 5 4 1 4
