FICON Administrator's Guide v6.4.0 (53-1001771-01, June 2010)

FICON Administrator’s Guide 57
53-1001771-01
Port Fencing
5
Figure 19 on page 56 shows the following Enhanced TI Zoning definitions for the emulation
topology:
• Green TI zone includes channel 0, ISL 80, ISL 81, Grid 1, and Grid 4.
• Blue TI zone includes channel 1, ISL 82, ISL 83, and CU Grid-4.
The unique characteristic of these zones is that each channel is defined with two control unit
device ports and one of the control unit device ports, CU Grid-4, is in both zones. In a traditional TI
Zone definition, these zones would have to be combined to provide the appropriate connectivity,
but then in the event of an ISL failure it would lead to a multi-hop, multi-emulation path that would
severely affect performance. Multi-hop paths are not certified for FICON configurations.
Port Fencing
Occasionally, bad optics and cables can cause errors to occur at a rapid rate that error processing
and sending and processing RSCNs can cause fabric performance problems. Port fencing allows
the user to limit the number of errors a port can receive by forcing a port offline when certain error
thresholds are met.
The port fencing feature is part of Fabric Watch and is configured through the fabric watch
fwConfigure command. This command prompts the user through a series of menus. There are no
parameters for this command. Alarms are turned on and off with the fwAlarmsFilterSet command.
For more information on configuring Port Fencing, refer to the Fabric Watch Administrator’s Guide.
Defining port fencing
1. (Optional) Clear all alarms.
2. Define threshold levels.
3. Define alarm action.
4. Activate alarming.
NOTE
Establish a Telnet session with a tool such as Putty that allows the columns to be increased. This is
because some of the displays use more than the standard 80 columns that programs such as
HyperTerminal support. Recommended number of columns is 120.
Settings for FICON Environments
For typical FICON environments, port fencing is usually only set for CRC errors and Invalid Words.
The default of 1,000 errors per minute is a little high for CRC errors and Invalid Words. A more
common setting is 50 errors per minute. This is high enough to ignore occasional errors and
transient errors due to re-cabling but low enough to stop problematic optics from causing fabric
issues.
By default, the alarms are set to fence the port, log an alert, send an e-mail, and set an SNMP trap.
In most FICON environments, only fencing the port and logging the alert are desired.
The following are the default thresholds: