Recently we purchased 5 servers. It has 4 10GB ports + 1 1GB Management port, as follow:

4x 10GB ports per server (2x traffic, 2x ISCSI), and (1x 1GB management port)

However, we are trying to see if it's possible to connect these servers to a 1G switch, since they are not the same.

1G Switch vs 10G server ports

Now, my questions is, would it see a mismatch and basically nothing but errors in the communication?

I know some server boards are hard coded to run 10G but I believe most can downgrade to match the switch port. However if it can't upgrade, what would be the best solution?

  • Are the 10G ports fiber or copper?
    – Ron Trunk
    Feb 21 '20 at 14:35
  • would you be able to explain both scenarios for me? copper and fiber ?
    – Roham
    Feb 21 '20 at 14:53
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
    – Ron Maupin
    Dec 17 '20 at 15:39

There are two basic kinds of 10G Ethernet ports:

8P8C aka RJ45

just connect to 1G 8P8C (1000BASE-T), pretty much all 10G ports are downward compatible with 1G

8P8C port


You'd need to check whether 1G SFP copper modules are available and which ones are compatible. A copper modules on one side allows you to connect to an 8P8C port on the other.

SFP ports1000BASE-T copper module

If the SFP+ ports are not compatible with 1G copper modules (1000BASE-T) then you'll need fiber SFPs, one compatible with the server, one compatible with the switch, both using the same Ethernet type. The most reasonable type should be 1000BASE-SX for multi-mode fiber.

fiber SFP

If the SFP+ ports are not compatible with 1G at all you'll need a switch with 10G SFP+ ports and use either 10GBASE-SR or DACs (direct-attach copper).

  • Thanks Zac, the vendor said we can run that 10G adapter at 1G speed, we'd need a transceiver to do that. The transceivers are not cheap however. As a suggestion, we could simply replace the PHY card on the back of the server with a 1G adapter. This is a more cost effective approach. When we move to the 10G you would put the original PHY card back in. What would be your comment on this please?
    – Roham
    Feb 27 '20 at 3:48
  • Of course, using a 1G NIC is an alternative. Sometimes lights-out management functions are somewhat limited which generic adapters, and the fully supported part might not be too cheap either. Note that there's a large market for "third-party compatible" SFP modules and DACs that may or may not be another alternative for you to the "original" module.
    – Zac67
    Feb 27 '20 at 7:22

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