Modes Of Operation - Extreme Networks ExtremeWare Version 7.8 Troubleshooting Manual

Diagnostics
scanning and memory mapping diagnostics are used to identify and correct switch fabric checksum
errors.
Memory scanning and memory mapping are two separate functions: scanning detects the faulted
portion of the memory; mapping re-maps the memory to remove the faulted memory section.
Memory scanning is designed to help isolate one of the major root causes of fabric checksum errors:
single-bit permanent (hard) failures. Memory scanning detects—with a high probability—all current
single-bit permanent (hard) failures in the switch memory that would result in fabric checksum errors.
Memory mapping can correct up to eight of these detected permanent (hard) single-bit errors by
reconfiguring the memory maps around the problem areas.
The packet memory scan examines every node of packet memory to detect packet errors by writing
data to packet memory, then reading and comparing results. The test is invasive and takes the switch
fabric offline to perform the test.
Errored cell correction:
• If the test detects eight or fewer error cells, those error cells will be mapped and excluded from use.
The module will continue to operate.
• If the test detects more than eight error cells, the module is identified as "failed" and must be
replaced.
You should use this test when the system log displays some intermittent or sporadic error messages
that might indicate a problem, but do not provide sufficient information to confirm the problem or
isolate the fault.

Modes of Operation

The Memory Scanning feature has two modes of operation:
• Manual mode (the default and recommended mode)
• Automatic mode (which should be used only in redundant networks)
NOTE
The memory scanning facility is a highly CPU intensive application and will consume full CPU cycles
when executed.
Memory scanning is supported on the following "i" series platforms and modules:
• BlackDiamond 6816, BlackDiamond 6808, and BlackDiamond 6804
• BlackDiamond modules: MSM, F96Ti, F48Ti, G8Xi, G8Ti, G12SXi, G16Xi, G16Ti, 10G Xenpak
• Alpine 3808, Alpine 3804, and Alpine 3802 (manual mode only)
• Summit48i, Summit7i, Summit5i, Summit1i, and Summit48si (manual mode only)
Manual Mode. A manual CLI command issued from any administrator level session initiates the
manual mode, as its name implies, for initiating memory scanning. Note that when memory scanning is
executed, it should be done so with the awareness that other tasks requiring CPU service cycles will be
impacted.
54 Advanced System Diagnostics and Troubleshooting Guide