User manual

2
CLI Commands
2-151
perf
perf.preferredPath
The perf.preferredPath commands enable you to use the preferred path
feature to influence the route of data traffic that traverses multiple
switches or directors in a fabric. If more than one ISL connects
switches in your SAN, this feature is useful for specifying an ISL
preference for a particular flow.
The preferred path feature allows the user to enhance the path
selection algorithm of the switch by providing the ability to prioritize
ISLs for a selected port on the switch. The preferred path capability
customizes the static load-balancing function by allowing the user to
specify an ISL preference for each remote domain. preferred path,
however, is still subject to the standard Fabric Shortest Path First
(FSPF) requirements, which allow the firmware to override the
configuration setting if errors are encountered.
The data path consists of the source port of the switch or director
being configured, the exit port of that switch or director, and the
domain ID of the destination switch or director. Each switch or
director must be configured for its part of the desired path in order to
achieve optimal performance.
You may need to configure preferred paths for all switches or
directors along the desired path for a proper multi-hop preferred
path. (For examples of preferred path implementation and other
related information, see the Element Manager manual your switch or
product.)
The following rules apply when configuring preferred paths:
• The domain ID of the switch must be set to insistent.
• Domain IDs must be in the range of 1 -31.
• The specified numbers for source ports and exit ports must be in
the range equal to the number of ports for the switch being
configured.
• For any source port, only one path may be defined to each
destination domain ID.