Connectrix DS-6520B: sfpshow displays "Cannot read Serial Data!" or "Does not use an SFP or is disabled"
Summary: The command output for sfpshow displays invalid output for online ports as "Cannot read Serial Data!" or "Does not use an SFP or is disabled" for online ports.
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Symptoms
In the "sfpshow," the following output may be observed for online ports.
Port X: id Can not read Serial Data!
Or
Port X does not use an SFP or is disabled
(where X is the port number)
Example output of "sfpshow":
Port 52: id Can not read Serial Data! Port 53: id Can not read Serial Data! Port 54: id Can not read Serial Data! Port 55: id Can not read Serial Data!
Example output of "sfpshow -all":
============= Port 7: ============= Port 7 does not use an SFP or is disabled! ============= Port 8: ============= Port 8 does not use an SFP or is disabled!
Cause
This may be seen under rare i2C access contention situations on switches only.
Resolution
Workaround:
It may be possible to get temporary recovery from performing a cold reboot or reseating the SFP. But it is highly recommended to upgrade to a version of Fabric OS with the fix.
Permanent Fix:
Upgrade firmware to FOS v7.3.1e, v7.3.2, or v7.4.1 and later
The corrective code prevents the issue from occurring, but does not correct a port in that state once the upgrade is complete. Once upgraded, if there are ports still in this state, it is recommended to use the Workaround to clear the condition.
Affected Products
Connectrix DS-6520BProducts
Connectrix B-Series Hardware, Connectrix DS-6510B, Connectrix DS-6520BArticle Properties
Article Number: 000065649
Article Type: Solution
Last Modified: 29 Oct 2025
Version: 4
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