Nexus 93108TC-FX3P: QSFP-100G-CU1M link only comes up when speed is set before inserting the cable
Two Cisco Nexus 93108TC-FX3P switches on NX-OS 9.3(11) are connected with genuine QSFP-100G-CU1M DACs but the link never comes up. The compatibility matrix says the cable is supported from NX-OS 9.3.5. The port config is a plain 'switchport mode trunk' / 'no shutdown', and 'show interface eth1/54 transceiver details' identifies the cable correctly: 'type is QSFP-100G-CR4', 'name is CISCO-LEONI', 'part number is L45593-D218-D10', 'cisco product id is QSFP-100G-CU1M', 'cisco part number is 37-1666-01', 'DOM is not supported'. Four different cables were tried and FEC was disabled, without success. When trying to hard-code the port, the poster found that the speed/duplex/negotiation commands are not even available while the cable is inserted.
- Hardware: Cisco Nexus 93108TC-FX3P
- Transceivers: QSFP-100G-CU1M (CISCO-LEONI L45593-D218-D10)
- Form factor: QSFP28, DAC
Symptoms / messages:
link down on QSFP-100G-CU1M between two Nexus 93108TC-FX3P
DOM is not supported
speed/duplex/negotiation commands not available while the cable is inserted
disabling FEC did not help
Comments 2
Set speed and duplex manually under the interfaces. Since the speed command gets rejected while the DAC is plugged in, I removed the cable, configured 'speed' on the port first, then reinserted the cable - and the 100G link came right up.
I checked the Cisco TMG compatibility matrix - this is supported since NX-OS 9.3.5. Could the cable be bad? Are the ports admin down? Does the switch even recognize the cable?