Dell POWEREDGE M1000E - Manual (Page 90)

70 Fabric Watch Administrator’s Guide
53-1002752-01
Port fencing
7
NOTE
The execution of the portFencing command is subject to Virtual Fabric (VF) or Admin Domain
restrictions that may be in place. For example, in non-VF chassis environments, the state change
counter of a trunked slave port gets incremented by more than 1 when the master EX_Port changes
its state. Therefore, it is advisable to set the port fencing high threshold for the State Change area
to a value greater than 4 in this environment.
The allowed threshold configuration settings are displayed on a per-class basis. FOP_Port class
thresholds apply to the entire switch. You can set different thresholds for Storage and Host
FOP_Ports if they are on different switches, based on the fabric configuration.
Port fencing configuration
You must configure port thresholds with the portThConfig command before you can enable port
fencing using the portFencing command. See
“portThConfig command procedures” on page 59 for
example port configurations, or refer to the Brocade Fabric OS Command Reference Guide for
complete inThreshold recommendations for CRC errors and Invalid Words.
You can configure a specified port type or a list of port types to enable port fencing for one or more
areas. Use the all option to indicate all port types or all areas.
Port fencing recommended area settings
Cyclic redundancy check (CRC) errors and invalid transmission words (ITW) can occur on normal
links. They have also been known to occur during certain transitions such as server reboots. When
these errors occur more frequently, they can cause a severe impact. While most systems can
tolerate infrequent CRC errors or invalid words, other environments can be sensitive to even
infrequent instances. The overall quality of the fabric interconnects is also a factor.
NOTE
For Fabric OS versions 7.1.0 and later, the ITW counter includes a physical coding sublayer (PCS)
violation. ITW violations can occur due to an ITW violation, a PCS violation, or both.
When establishing thresholds for CRC errors and Invalid Words, consider the following:
• In general, “cleaner” interconnects can have lower thresholds as they should be less likely to
introduce errors on the links.
• Moderate (recommended), conservative and aggressive threshold recommendations are
provided in
Table 21 . After selecting the type of thresholds for an environment:
- Set the low threshold with an action of ALERT (RASlog, e-mail, SNMP trap). The alert will be
triggered whenever the low threshold is exceeded.
- Set the high threshold with an action of Fence. The port will be fenced (disabled) whenever
the high threshold is detected.
• Aggressive threshold suggestions do not include settings for low, and instead only have the
high values to trigger fencing actionformation on the portThConfig command.
Table 21 shows the recommended moderate, aggressive, and conservative thresholds for
supported port fencing areas.