Symptom

In a Nexus 7K series switch with 40G F3 series line card, if a QSA module with 10G transceiver is inserted without breakout configuration, following symptoms can be seen 1)Port diag failures

2021 Mar 25 12:35:05 N7700 %$ VDC-1 %$ %DIAG_PORT_LB-2-PORTLOOPBACK_TEST_FAIL: Module:7 Test:PortLoopback failed 10 consecutive times. Faulty module: affected ports:9 Error:Loopback test failed. Packets lost on the SUP in the transmit direction

2)Egress buffer stuck condition. When breakout is configured when in this state, traffic forwarding on other interfaces in the module also can be affected

Conditions

A QSA module with 10G transceiver is inserted without breakout configuration is inserted in 40G port of an F3 series line card.

Workaround

If already in this condition, remove QSA module and reload switch. Prior to insertion of QSA module, configure breakout using command

interface breakout module <> port <> map 10g-4x

Further Problem Description