If you are seeing this error message when configuring a Cisco FEX with more than 1 uplink to the same switch, follow the below setups to troubleshoot
Switch(config-if)# sho int e1/11
Ethernet1/11 is down (FEX identity mismatch)
Syslog Messages During configuration
2019 Apr 11 16:23:02 Switch %FEX-5-FEX_PORT_STATUS_NOTI: Uplink-ID 2 of Fex 0 that is connected with Ethernet1/11 changed its status from Discovered to Created
2019 Apr 11 16:23:02 Switch %FEX-5-FEX_PORT_STATUS_NOTI: Uplink-ID 2 of Fex 102 that is connected with Ethernet1/11 changed its status from Created to Configured
Switch(config-if)# 2019 Apr 11 16:23:09 Switch %ETHPORT-5-SPEED: Interface Ethernet1/11, operational speed changed to 10 Gbps
2019 Apr 11 16:23:09 Switch %ETHPORT-5-IF_DUPLEX: Interface Ethernet1/11, operational duplex mode changed to Full
2019 Apr 11 16:23:09 Switch %ETHPORT-5-IF_RX_FLOW_CONTROL: Interface Ethernet1/11, operational Receive Flow Control state changed to off
2019 Apr 11 16:23:09 Switch %ETHPORT-5-IF_TX_FLOW_CONTROL: Interface Ethernet1/11, operational Transmit Flow Control state changed to off
2019 Apr 11 16:23:09 Switch %FEX-5-FEX_PORT_STATUS_NOTI: Uplink-ID 0 of Fex 102 that is connected with Ethernet1/11 changed its status from Configured to Fabric Up
2019 Apr 11 16:23:09 Switch %FEX-2-FEX_PORT_STATUS_CRIT: Uplink-ID 2 of Fex 102 that is connected with Ethernet1/11 changed its status from Fabric Up to Identity-Mismatch
Why Is this happening??
When a FEX connects to a Nexus switch the Nexus Switch assigns the FEX an ID. If the switch tries to assign a different ID to different port on the same FEX, the “Identity-Mismatch” will occur.
Verification by running “Show interface fax-fabric”
As the below shows, FEX with serial number: FOX1930GDBQ was assigned two different FEX IDs:
- 102
- 104
FEX ID 104 was assigned first. When 102 was assigned, it caused a mismatch.
sho interface fex-fabric
Fabric Fabric Fex FEX Fex
Fex Port Port State Uplink Model Serial
---------------------------------------------------------------
101 Eth1/3 Active 1 N2K-C2232PP-10GE SSI1634047R
101 Eth1/4 Active 2 N2K-C2232PP-10GE SSI1634047R
103 Eth1/5 Active 1 N2K-C2248TP-E-1GE SSI16270C8Z
105 Eth1/6 Active 1 N2K-C2232PP-10GE SSI15510STZ
104 Eth1/10 Active 1 N2K-C2248TP-E-1GE FOX1930GDBQ
102 Eth1/11 Identity-Mismatch 2 N2K-C2248TP-E-1GE FOX1930GDBQ
105 Eth1/12 Active 2 N2K-C2232PP-10GE SSI15510STZ
--- Eth1/13 Discovered 1 N2K-C2248TP-E-1GE FOX1930GDE3
--- Eth1/14 Discovered 2 N2K-C2248TP-E-1GE FOX1930GDE3
How to Fix this?
Fix the cabling physically by swapping the cables to how you want it physically setup
If the desire was to be consistent in the cabling diagram, then it would be best not to deviate from a standard since standards are hard to come by these days 🙂
Reconfigure it based on our it’s already cabled
If there is less of a standard, then just reconfigure the switch
- Default the interface
default interface e1/11
- configure the misconfigured interface e1/11 with the same configure from FEX ID 104 (interface e1/10)
-
Switch(config-if)# show run int e1/10 !Command: show running-config interface Ethernet1/10 !Time: Thu Apr 11 16:27:05 2019 version 7.3(2)N1(1) interface Ethernet1/10 description FEX104 grid DL37-1G switchport mode fex-fabric fex associate 104 no snmp trap link-status channel-group 104
-
- Now the FEXs are happy
-
Switch# show interface fex-fabric Fabric Fabric Fex FEX Fex Fex Port Port State Uplink Model Serial --------------------------------------------------------------- 101 Eth1/3 Active 1 N2K-C2232PP-10GE SSI1634047R 101 Eth1/4 Active 2 N2K-C2232PP-10GE SSI1634047R 103 Eth1/5 Active 1 N2K-C2248TP-E-1GE SSI16270C8Z 105 Eth1/6 Active 1 N2K-C2232PP-10GE SSI15510STZ 104 Eth1/10 Active 1 N2K-C2248TP-E-1GE FOX1930GDBQ 104 Eth1/11 Active 2 N2K-C2248TP-E-1GE FOX1930GDBQ 105 Eth1/12 Active 2 N2K-C2232PP-10GE SSI15510STZ 102 Eth1/13 Active 1 N2K-C2248TP-E-1GE FOX1930GDE3 102 Eth1/14 Active 2 N2K-C2248TP-E-1GE FOX1930GDE3
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