Fabric OS Reference Manual

66 Fabric OS Reference Manual
dlsSet
Turn on dynamic load sharing option.
Synopsis
dlsSet
Availability admin
Description Use this command to enable dynamic load sharing when a fabric change
occurs.
Routing is done on a per source port basis. This means that all the traffic
coming in from a port (either E_Port or Fx_Port) directed to the same
remote domain is routed through the same output E_Port.
To optimize fabric utilization, when there are multiple equivalent paths to a
remote switch, traffic is shared among all the paths. Load sharing takes
place when a switch reboots. In addition, if dynamic load sharing is
enabled, the optimal load sharing is recomputed every time a change in the
fabric occurs. A change in the fabric is defined as an E_Port going up or
down, or an Nx_Port going up or down.
If dynamic load sharing is turned off, load sharing is performed only at boot
time or when an Nx_Port comes up. Optimal load sharing is rarely achieved
with this setting.
Dynamic load sharing is on by default.
When dynamic load sharing is set, routing changes can affect working
ports. For example, if an Fx_Port goes down, another Fx_Port may be
rerouted from one E_Port to a different E_Port. The switch minimizes the
number of routing changes, but some are necessary in order to achieve
optimal load sharing. These changes can affect the application, especially if
the ‘in-order delivery’ option is set. With the in-order delivery option (see
iodSet
), routes are not available for a few seconds after a fabric change. In
addition, some frame loss may occur. No frame loss occurs if in-order
delivery is off, but there is still a short period of time when traffic is not
forwarded. This period of time is significantly shorter than when in-order
delivery is on, and is usually less than 1 second.