Fabric Manager Users Guide, Version 6.1, Revision A - QLogic

2–Advanced Fabric Manager Capabilities
SM Loop Test
SM Loop Test
Loop Test introduction
The SM Looptest is a diagnostic test facility in the SM. As part of this test, the SM
stress tests inter-switch links (ISLs) by continuously passing traffic through them.
Other tools like FastFabric can be used to monitor the links for signal integrity
issues or other errors. The advantage of the Looptest, is that it provides a
guaranteed way to test all of the ISLs in the fabric, without the need for a large
number of end hosts or applications.
When the Looptest is started, the SM deliberately sets up certain additional routes
with loops in addition to the normal routes that are setup to enable communication
with end ports. These loop routes only include ISLs and are not used for
communication with end ports, but are used only to stress test the ISLs. Each loop
route starts from a switch, A (Figure 2-14), uses one of its ISL to another switch
and pass through a set of other ISLs and switches (say B, C, D) and ends up back
at switch A but via a different ISL.
A
B
D
C
Figure 2-14. ISL Loop Routes
WARNING!!
• Loop test should not be run when applications are running on the fabric.
The loop test introduces high volume traffic on the switch ISLs which
would slow down normal application traffic.
• Since there are additional LIDs for each of the loop route LIDs, the user
may observe a large number of additional LIDs in the switch LID
Forwarding Tables (LFTs) when the loop test is running.
IB0054608-01 B 2-35