Symptom
It is observed in the field that C9300X having SFP-10G-T-X Copper transceiver with Serial Number MTC24xxxx or MTC25xxxx or MTC26xxxx connection to a peer end device (like a windows PC) exhibits random packet loss.
As of now, no special error counters are found.
Conditions
C9300X with SFP-10G-T-X (having Serial Numbers MTC24xxxx or MTC25xxxx or MTC26xxxx), C9300X running 17.6.x and 17.7.x.
The problem occurs after going through an OIR event (starting at system boot).
This issue is not applicable for SFP-10G-T-X operating in 10G speed
Workaround
1/ Pick an unused port (that has not been used since last bootup of switch) for insertion of SFP-10G-T-X intended to operate in 1G speed.
2/ After removal of SFP-10G-T-X operating in 1G speed, insert any other 10G transceiver/PID (Eg: SFP-10G-SR).
After detection of the transceiver is successful remove it (no need to establish the link UP with a peer). Finally, insert the SFP-10G-T-X.
3/ Reload the switch to clear the issue.
Further Problem Description
SFP-10G-T-X can operate at different speeds (1G or 10G) depending upon interface speed configuration or auto-negotiation with the peer.
Once SFP-10G-T-X is removed from the port, switch software does clean-up activity to reset the port to default setting.
When SFP-10G-T-X is operating in 1G speed, certain internal settings (speed/mode) are not getting cleaned-up during the transceiver removal and these settings remain as a stale data.
Now if SFP-10G-T-X transceiver is re-inserted on the same port, due to the existing stale data, the initialization of the transceiver is not successful and leads to random packet drops.
