Reference Guide

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 example, if a link goes down), traffic is rerouted around the failure, and some frames
could be delivered out of order. Most destination devices tolerate out-of-order delivery, but some do not.
By default, out-of-order frame-based delivery is allowed to minimize the number of frames dropped. Enabling in-order delivery (IOD)
guarantees that frames are either delivered in order or dropped. You should only force in-order frame delivery across topology changes
if the fabric contains destination devices that cannot tolerate occasional out-of-order frame delivery.
Forcing in-order frame delivery across topology changes
Use the following procedure to force in-order frame delivery across topology changes.
1. Connect to the switch and log in using an account with admin permissions.
2. Enter the iodSet command.
NOTE
The iodSet command can cause a delay in the establishment of a new path when a topology change occurs; use it
with care.
3. Confirm the in-order delivery has been set by entering the iodShow command.
Restoring out-of-order frame delivery across topology changes
Use the following procedure to restore out-of-order frame delivery across topology changes.
1. Connect to the switch and log in using an account with admin permissions.
2. Enter the iodReset command.
Enabling Frame Viewer
The Frame Viewer application allows you to view the contents of discarded frames, which can be recorded at up to 40 frames per
second per ASIC.
To enable Frame Viewer, complete the following steps.
1. Connect to the switch and log in using an account with admin permissions.
2. Enter frameLog --enable -type type .
The following table lists the supported values for type . If the -type option is not provided, then all three discard frame types will
be recorded.
Option Description
timeout Due to timeout.
du Due to destination unreachable.
unroute Due to unrouteable frame.
3. Use the frameLog --status command to view the configuration. The following is a typical example of the output of this
command:
switch:admin> framelog --status
Service Status: Enabled
Enabled Disc Frame Types: timeout unroute
Routing Traffic
Brocade Fabric OS Administration Guide, 8.0.1
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