Troubleshooting and Diagnostics Guide

92 Fabric OS Troubleshooting and Diagnostics Guide
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Diagnostic Port (D_Port)
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• Size of test frames
• Duration of test
• User-defined test payload
• Predefined pattern for use in test payload
• Testing with forward error correction (FEC) on or off (default is off)
• Testing with credit recovery (CR) on or off (default is off)
D_Port test initiation modes and test start behavior
Table 20 summarizes D_Port test initiation modes and test start behavior.
General limitations and considerations for D_Port
• The link to be tested must be marginally functional and able to carry a minimal number of
frames before it can become a D_Port link. The D_Port feature is useful for diagnosing
marginal faults only; it cannot detect the failure of any single component.
• On ICL ports that are configured as D_Ports, only link traffic can be run. Electrical and optical
loopback tests are not supported.
• Brocade recommends that D_Port tests be limited to a maximum of eight (8) D_Ports at once.
Otherwise, there is a possibility of false alarms. When a large number of D_Ports are
configured, the test is run on one port per blade at a time, and other ports wait until the test is
completed. No test begins until the fabric is stable.
• Note the following high-availability (HA) considerations:
- There is no HA support for D_Port test options and results. Consequently, such information
is not synchronized with the standby side. Any information from a previous test is lost
following a failover.
- An HA failover and reboot will restart the D_Port test from the beginning, and some of the
ports may fail depending on the design of a particular HBA. Restarting the test from either
side will recover from this post-failover situation and allow the test to run to completion.
• D_Port on an Access Gateway is supported only when there is no mapping between N_Ports
and F_Ports; this includes static mapping and preferred port mapping. [In addition, device
(WWN) mapping is also not retained when D_Port is used.] If an Access Gateway port to be
tested is mapped, the port mapping (including static and preferred port mapping) must be
removed before D_Port can be used. (See “Saving port mappings on an Access Gateway” on
page 97.)
• See also“Limitations and considerations for D_Port with HBAs” on page 99 .
TABLE 20 D_Port test initiation modes and test start behavior),
Mode/behavior Description
Initiation mode Static User configures port explicitly. Port remains as D_Port until user removes
configuration.
Dynamic No user configuration required. D_Port mode is initiated by external request from
remote port (a switch port if HBAs are used).
Test star t
behavior
Automatic User starts test (see “Automatic mode configuration” on page 98), but initial test
suite is run automatically.
Manual User starts test from switch side (using portdporttest - -start command) or from
HBA side (see “BCU D_Port commands” on page 99).