HP StorageWorks MSA 2.8 SAN Switch - Manual (Page 65)

Basic Switch Management
65 Fabric OS Procedures Version 3.1.x/4.1.x User Guide
Routing
In Order Delivery
In a stable fabric, frames are always delivered in order, even when the traffic
between switches is shared among multiple paths. However, when topology
changes occur in the fabric (for instance, a link goes down), traffic is rerouted
around the failure. When topology changes occur, some frames could be delivered
out of order.
The default behavior is to automatically enable out-of-order delivery of frames
during fabric topology changes; this enables fast rerouting after a fabric topology
change. See “
Forcing In-order Delivery of Frames ” on page 65 to change the
default routing settings during topology changes.
Dynamic Load Sharing
Routing is generally based on the incoming port and the destination domain. 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 routing, when there are multiple equivalent paths to a remote
switch, traffic is shared among all the paths. Load sharing is recomputed when a
switch is booted up or 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 Fx_Port going up or down.
See “
Using Dynamic Load-Sharing ” on page 66.
Forcing In-order Delivery of Frames
To force in-order delivery of frames during fabric topology changes:
1. Log into the switch as the admin user.
2. At the command line, enter the iodset command.
Example:
Note: This command can cause a delay in the establishment of a new path when a
topology change occurs, and should be used with care.
switch:admin> iodset
done.
switch:admin>