IBM SAN32M1, Installation And Service Manual

Page: 153 / 626

121 Chapter 2: Installation tasks
3. Set the Congestion Thresholds for ports as percentages of link
bandwidths, in the range of 1% through 99%. These thresholds
are used only when a port becomes an ISL. When the link’s traffic
load becomes greater than this percentage, the link is seen as
“congested” and traffic is rerouted (if possible) to an uncongested
link. Note that rerouting may not be possible if there are no
alternate links available or if alternate links are congested or
credit-starved.
NOTE: Using default settings for port congestion thresholds should
work well in most cases. This step is not required.
Set the Congestion Threshold using one of these methods:
• Click the check box under the Use Algorithmic Threshold
column to display a value under the Threshold % column. This
value is computed by the feature’s rerouting algorithm. If you
click this check box, you cannot enter a value into the Threshold
% column for the port.
If you click the check box to remove the checkmark, any value
that was set in the Threshold % column for the port will
redisplay.
• Click in the Threshold % column and enter a value in the range
of 1 through 99.
NOTE: If no threshold is entered for a port, a default value is used that is
based on port type (1 Gb/sec or 2 Gb/sec) and channel bandwidth.
4. Set Event Notification options. Note that, if enabled, these
notifications occur the first time the events occur. Notifications
are not resent while the problem persists.
• Unresolved Congestion. Click this check box to display a
checkmark and enable notification. If enabled, an “unresolved
congestion” entry is made to the Event Log and an SNMP trap
will be generated, if trap recipients are configured through the
Configure SNMP dialog box.
An unresolved congestion event occurs when the rerouting
algorithm cannot find a path for rerouting data flow and
relieving congestion on an ISL.