Score:0

Connecting an SFP+ port to a QSFP28 switch

cn flag

Background - I am working with a client trying to get a new Dell R540 server onto the client's network. They provided me with a single port on their Cisco Nexus 93240YC-FX2 Switch to connect the server to. The server has two 10GE SFP+ ports and we have a SFP+ 10GbE Twinax Direct Attach cable to work with.

It took some time to identify why the server was not registering that the cable was connected to the switch. The server provides 48 x 1/10/25-Gbps and 12 x 40/100-Gbps QSFP28 ports. So it would appear the issue is that the 10GE SFP+ port cannot communicate with the provided QSFP28 port.

Question - How do I connect the server to the switch and get them to communicate? Would it be simply programming the switch port? Or do I need an adapter? Or are they just completely incompatible?

Any help is appreciated, thank you!

Score:0
ru flag

When using any SFP/SFP+/QSFP/... port you need to make sure that the plugged module is compatible with the port. A physical fit is not enough. Some devices only accept modules branded to the vendor. Sometimes appropriate port configuration is required as well.

Multiple options:

  • plug the SFP+ DAC to an SFP+ port, not a QSFP one
  • buy a QSFP-to-SFP+ fanout
  • buy a QSFP-to-SFP+ adapter and use an SFP+ DAC
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