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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 at 14:35
  • would you be able to explain both scenarios for me? copper and fiber ? – Roham Feb 21 at 14:53
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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

SFP+

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).

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  • 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 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 at 7:22

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