HBA link diagnostics is a useful tool to validate the performance and isolate faulty remote-peer and HBA components. Different
types of tests are available to verify the operation of different components in the path to, and the stack of, the target
device.
Link diagnostics tests are configured and controlled from the MDS switch. The target HBA and SFP must support the intended
types of tests. The link is set to a diagnostic mode which removes it from the SAN fabric. The test traffic can then be run
exclusively on the specific link without interfering with the fabric traffic. When the tests are complete, the link can be
taken out of the diagnostic mode and returned to service in the SAN fabric.
Two ports, a diagnostic port and a generator port, are required to run the tests. The diagnostic port is the port on which
the tests are run. The generator port generates traffic required to run the tests. If the generator port is not explicitly
specified by the user while starting the diagnostics tests, then any port that is in admin shutdown status is selected as
the generator port.
The following are the different types of link diagnostics tests available on Cisco MDS switches:
-
Latency Test
-
Loopback Traffic Tests
Both the link diagnostics tests can be run at different supported levels. For more information, see the Levels of HBA Link Diagnostics Tests section.