HP StorageWorks 2.32 Edge Switch - Manual (Page 160)

Optional features 160
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.
NOTE: If you clear the check box, any value that was set in the Threshold % column for the port
redisplays.
• Click in the Threshold % column and enter a value in the range of 1 through 99.
NOTE: You must either specify a value in the Threshold % column or click the Use Algorithmic
Threshold check box.
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 enable notification. If enabled, an
unresolved congestion entry is made to the Event Log and an SNMP trap is generated if trap
recipients are configured through the Configure SNMP dialog box.
NOTE: An unresolved congestion event occurs when the rerouting algorithm cannot find a path
for rerouting data flow and relieving congestion on an ISL.
• Back Pressure. Click this check box to enable this option. If enabled, a back pressure
entry will be made to the Event Log and an SNMP trap will be generated if trap recipients
are configured through the Configure SNMP dialog box.
A back pressure event occurs when the percentage of time the ISL lacks BB_Credits exceeds
the threshold. A separate event also occurs when the backpressure condition ends.
5. Set the Low BB Credit Threshold:
NOTE: Using default settings for this threshold should work well in most cases. This step is not
required.
This is the percentage of time that the transmitting link cannot transmit because BB_Credit is
unavailable. It is the percent of time that the link can be treated as back-pressured by the
rerouting algorithm. This value is also used when determining routes for a transmit link. A
back-pressured ISL cannot be the recipient of traffic rerouted from other ISLs, and traffic on a
back-pressured ISL may be rerouted even if the ISL is not congested.
• Click Default Threshold and a default value (1 to 99%) appears in the Threshold box.
If the default is enabled, you cannot enter values into the box.
• Click in the threshold box and enter a value from 1 to 99.
6. Click Activate to enable these values on the switch and close the dialog box.