HP StorageWorks 2.64 Director Switch - Manual (Page 166)

Optional features 166
is to make the most efficient possible use of redundant ISLs between neighboring switches, even if
these ISLs have different bandwidths.
Load-balancing among the ISLs does not require user configuration, other than enabling Open
Trunking. However, if desired, you can modify default settings for congestion thresholds (per port)
and low BB_Credit threshold.
In particular, you do not need to manually configure ISLs into trunk groups of redundant links where
data can be off-loaded. Candidate links for rerouting flow are identified and maintained
automatically. This means that flow may be rerouted onto a link that goes to a different adjacent
switch, as long as that link is on the least cost/shortest path to the destination domain ID.
To install and enable this option, select the Configure Feature Key option under the Element
Manager’s Configure menu. See ” Configuring feature key ” on page 113.
Enabling and configuring Open Trunking
To enable Open Trunking for a specific switch and configure threshold values and event
notification options, use the following steps.
1. Select Open Trunking from the Configure menu. The Configure Open Trunking dialog box
appears, as shown in Figure 75 .
Figure 75 Configure Open Trunking dialog box
2. Enable Open Trunking by clicking the Enable Open Trunking check box to display a check
mark.
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 have no available
BB_Credit.