Will a 10GbE SFP+ NIC accept a 1G single-mode SFP optic?
3
The poster was building a server that needed a 1 Gbps single-mode fibre uplink and wanted a PCIe card with two to four SFP cages so any optic could be used later. The core doubt: switches usually accept plain 1G SFP optics in SFP+ ports, but is the same true for 10GbE server NICs, or would the NIC refuse the slower module? No specific error was seen yet; this was a pre-purchase compatibility question about mixing SFP (1G) optics with SFP+ (10G) network adapters.
- Hardware: Mellanox ConnectX-2 EN, Mellanox ConnectX-3 EN
- Transceivers: generic 1G single-mode SFP
- Form factor: SFP, SFP+
Symptoms / messages:
pre-purchase compatibility question
1G optic in 10G NIC port
Comments 2
Most 10GbE SFP+ NICs do accept 1G SFP optics; the Mellanox ConnectX series (ConnectX-2 and ConnectX-3, 10GbE variants) was confirmed to work with standard SFP optics.
Make sure the card is a real 10GbE SFP+ model: 40GbE ConnectX-3 cards with QSFP cages will not work with SFP optics, not even through a QSFP-to-SFP adapter.