Cisco module signature: bytes 96-127 must match the serial number or a recoded SFP is rejected

Question

Discussion of why re-coded modules fail Cisco validation: Cisco SFPs carry a unique signature tied to each serial number in bytes 96-127, and editing vendor name or serial makes the signature no longer match, so the switch rejects the module unless the signature is regenerated. Hardware involved: Cisco switches, Cisco SFP, recoded third-party SFP.

Hardware: Cisco switches
Transceivers: Cisco SFP, recoded third-party SFP
Form factor: SFP

Symptoms / messages:

recoded SFP rejected by Cisco
signature not equal to serial number

qsfpwolf · Accepted Answer

After changing vendor name, serial or date the Cisco signature at bytes 96-127 must be recalculated with a proprietary algorithm from vendor name, serial and date; without regenerating it the module stays non-compatible.

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