156-836 · Question #101
Which setting is required in order to connect an appliance with 40Gbps downlink interface and DAC to the Orchestrator MHO-140?
The correct answer is A. On Orchestrator: Change QSFP mode from 100Gbps to 40Gbps. The MHO-140 Orchestrator uses QSFP/QSFP28 ports (ports 49-55) that default to 100Gbps mode but support 40Gbps connections via DAC cables to appliances with 40Gbps downlink interfaces. The required command set maestro port <Port ID> qsfp-mode 40G must be run on the Orchestrator…
Question
Which setting is required in order to connect an appliance with 40Gbps downlink interface and DAC to the Orchestrator MHO-140?
Options
- AOn Orchestrator: Change QSFP mode from 100Gbps to 40Gbps
- BOn Orchestrator: Change port type from uplink to downlink
- COn Appliance: Change a port speed to 10Gbps
- DNo change required
How the community answered
(37 responses)- A89% (33)
- B3% (1)
- C3% (1)
- D5% (2)
Explanation
The MHO-140 Orchestrator uses QSFP/QSFP28 ports (ports 49-55) that default to 100Gbps mode but support 40Gbps connections via DAC cables to appliances with 40Gbps downlink interfaces. The required command set maestro port <Port ID> qsfp-mode 40G must be run on the Orchestrator to change the QSFP mode from 100Gbps to 40Gbps for compatibility. No appliance- side changes or port type modifications are needed, as downlink ports natively support this after reconfiguration.
Topics
Community Discussion
8
Ingrid P.May 29, 2026The answer is A. The MHO-140 Orchestrator ships with QSFP ports defaulting to 100Gbps mode, and when you connect a 40Gbps DAC, you must manually switch the QSFP mode down to 40Gbps on the Orchestrator side, otherwise the link will not come up because the ports are negotiating at mismatched speeds.
Lena V.May 31, 2026Worth adding for the exam: QSFP links on the MHO-140 do not autonegotiate speed the way copper ports do, so the test will likely expect you to know that the failure mode is a hard link-down, not a speed mismatch warning, which is why candidates mix this up with standard SFP+ behavior.
Samuel O.Jun 8, 2026The B distractor got me the first time I read this because in physical networking you do think about port roles, but the MHO-140 Orchestrator has QSFP ports that default to 100Gbps mode and a DAC connecting a 40Gbps appliance just will not negotiate correctly until you manually set that QSFP to 40Gbps mode on the Orchestrator side, so A is the move.
Nina C.Jun 25, 2026So I got this one right but I want to make sure I understand the why, not just the what. The MHO-140 uses QSFP ports that default to 100Gbps mode, and since DAC cables are passive and just carry whatever speed both ends negotiate, if the appliance is only doing 40Gbps on its downlink side, the Orchestrator has to be brought down to match, otherwise the link just will not come up. That points to A, because the change has to happen on the Orchestrator side to match what the appliance is already running. My question is, does the Orchestrator let you set that QSFP mode per port, or does changing it affect all ports in that group at once, because I could see that mattering a lot if you have a mixed environment with some 100Gbps and some 40Gbps appliances hanging off the same Orchestrator?
Anastasia B.Jun 27, 2026Port type has to flip to downlink on the Orchestrator, that is B.
Samuel O.Jun 27, 2026Anastasia, actually the answer is A, because the port facing the Orchestrator is the uplink side, not the downlink, so the device below it is the one whose port type gets set to uplink to reach the controller above it. Think of it like a switch stack where "uplink" always points toward the management plane, not away from it.
Lena V.Jun 1, 2026Tested this in our lab last month, the MHO-140 auto-negotiates the DAC connection and recognizes the 40Gbps downlink without any manual mode changes on either side, so D is correct and the other options are just distractors meant to trip up people who overthink the hardware config. The exam wants you to know that modern orchestrators handle this transparently, no intervention needed.
Ingrid P.Jun 3, 2026Lena, I get why D feels intuitive, but the exam is specifically testing that the MHO-140 requires you to explicitly set the port mode to 40G before the DAC link comes up, which is exactly what A covers. Auto-negotiation handles speed sensing on copper RJ45 ports, not on DAC or direct-attach interfaces, so that distinction is worth a card of its own.