Symptom

When a first-generation Nexus 9000 series switch has "no service unsupported-transceiver" configured alongside FEXs, FEX fabric interfaces will enter a "FEX-fabric sfp invalid" status after the switch is reloaded. `show interface brief` Eth1/44 1 eth access down XCVR not inserted auto(D) -- Eth1/45 1 eth fabric down FEX-fabric sfp invalid auto(D) 121 Eth1/46 1 eth fabric down FEX-fabric sfp invalid auto(D) 122 Eth1/47 1 eth access up none 10G(D) -- Eth1/48 1 eth access up none 10G(D) --

Conditions

This issue is observed under the following conditions: 1. Affected switch is a first-generation Nexus 9000 series. Nexus 9000 series switches with the Cisco Cloud Scale ASIC are not affected by this issue. 2. Switch has "no service unsupported-transceiver" present in the running-config. `show running-config’ no service unsupported-transceiver 3. Switch has one or more FEXs connected and configured to FEX fabric interfaces (which are physical interfaces or port-channels with "switchport mode fex-fabric" configured on them) `show running-config` interface Ethernet1/45 switchport mode fex-fabric fex associate 121 channel-group 121 interface Ethernet1/46 switchport mode fex-fabric fex associate 122 channel-group 122

Workaround

To proactively prevent this issue from happening, ensure that "service unsupported-transceiver" is configured instead of "no service unsupported-transceiver". Note that "service unsupported-transceiver" is default configuration on Nexus 9000 series switches. An example of how to configure "service unsupported-transceiver" is shown below. switch# configure terminal switch(config)# service unsupported-transceiver switch(config)# end switch# To reactively work around this issue if it has already occurred, apply the following workaround: 1. Configure "service unsupported-transceiver" as shown above. 2. Administratively shut down affected interfaces with the "shutdown" command. switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# interface ethernet1/45-46 switch(config-if-range)# shutdown switch(config-if-range)# end switch# 3. Administratively bring affected interfaces back online with the "no shutdown" command. switch(config)# interface ethernet1/45-46 switch(config-if-range)# no shutdown switch(config-if-range)# end switch#

Further Problem Description