CSCwo18785: 'ERROR: The transceiver doesn't support this speed' with a third-party 200G DAC on Nexus 9332D-GX2B
4
The poster, validating their product against Cisco Nexus 9000 switches (a Nexus C9332D-GX2B chassis), is blocked by bug CSCwo18785: configuring 200G on a QSFP-200G DAC fails with 'ERROR: The transceiver doesn't support this speed'. The cable is a Mellanox MCP1650-H002E26 200GbE DAC; connected back-to-back between two NVIDIA ConnectX-7 NICs in an Ubuntu 24.x server, without the Cisco switch, it auto-negotiates to 200 Gbps normally. The poster asked for the current status of the bug, which build contains the fix and when it would be publicly available.
- Hardware: Cisco Nexus 9000 C9332D-GX2B, NVIDIA ConnectX-7 NIC (Ubuntu 24.x server)
- Transceivers: Mellanox MCP1650-H002E26 200GbE QSFP56 DAC
- Form factor: QSFP56, DAC
Symptoms / messages:
ERROR: The transceiver doesn't support this speed
cannot configure 200G on third-party QSFP-200G DAC
CSCwo18785
same DAC negotiates 200G between two ConnectX-7 NICs
Comments 4
Accepted: a respondent stated the bug is acknowledged as CSCwo18785 with a fix targeted for a release then in testing (they cited IOS-XE 17.9.3 with public availability around late Q3 2025, although the poster's platform is a Nexus running NX-OS) and advised opening a TAC case for an interim engineering build or workaround.
A respondent noted the bug is listed as Fixed but its conditions say it is only seen with third-party 200G DAC cables, so Cisco may not prioritise shipping the fix.
A respondent explained that a bug with status Fixed but no Known Fixed Releases means developers have fixed it but no customer release contains it yet; TAC can provide an ETA.
Another respondent recommended 'show interface transceiver support-list', 'show interface <x> capability | include speed' and 'show idprom interface <x>' to check for speed, connector type, wavelength, FEC and transceiver-type mismatches, noting Cisco added these commands to make such mismatches visible.