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Can you have an AMD with mixed interfaces running at different speeds?


I'm looking to install an AMD and was wondering:

1) Can we use a copper NIC card and a fibre NIC card on the same AMD, knowing that the copper will run at 1Gbps and the fibre at 10Gbps?

2) Can we mix physical mediums in general on the same AMD (copper, fibre)?

3) Can you mix speeds in general keeping the medium the same on the same AMD(some 1Gbps, some 10Gbps)?

4) Are there any drawbacks to any of those combinations, i.e. can we still utilise custom drivers? Can we still take advantage of HS AMD architecture?

Many thanks!



Hi Matt

Sure - you can mix speed and media as you please. The only thing that matter is that you have the exact same chip on the NIC. From the top of my head, I think you check this with the command LSPCI -nn or if it was -v ,and then you might net a few filters or pipes to weed out all the unnecessary stuff.

Good to know.

In looking at the HS AMD (L) spec, we only support one chipset (Intel 82599), that does not allow for a 1Gbps copper interface with equivalent chipset. So I'm assuming there is a caveat there?


Yes - Didn't know that either!

But the PDF seems to indicate that you can at least have different speeds:

According to the Intel® 82599 10 GbE Controller Datasheet (see Section, Link is configured by setting the speed in the AUTOC.LMS field, selecting the appropriate physical interface in AUTOC.1G_PMA_PMD, AUTOC.10G_PMA_PMD_PARALLEL, and AUTOC2.10G_PMA_PMD_Serial and is completed by restarting auto-negotiation by setting AUTOC.Restart_AN to 1b.

Then you "only" have to get a media converter 🙂


Seems like it's not always possible to run different speeds on the same NIC:

"The 82599 supports 10 GbE operation, 1 GbE operation and 100 Mb/s Ethernet operation
on the MAUI interface. The 82599 can support different or the same link speeds (10 Gb/
s, 1 Gb/s and 100 Mb/s) and protocols on each of the two MAUI ports. The 82599 also
supports automatic crossover and polarity correction on each of the MAUI ports to
eliminate the need for crossover cables between similar devices. The 82599 also supports
auto-negotiation when configured for backplane Ethernet to automatically select between
KX, KX4 and KR.
When in 10 GbE operating mode, the MAUI interface can be configured as any of the
• A four lane XAUI interface.
• A four lane 10GBASE-BX4 interface.
• A four lane 10GBASE-KX4 interface.
• A four lane 10GBASE-CX4 interface.
• A single lane 10GBASE-KR interface.
• A single lane SFI interface.
When in 1 GbE operating mode, the MAUI interface can be configured as any of the
• A single lane 1000BASE-KX interface.
• A single lane 1000BASE-BX interface.
• A single SGMII (1 Gb/s or 100 Mb/s) lane over a KX or BX compliant electrical

But it takes down to 10 Mbps

Based on conversations, it looks like you can run a mix of copper and fibre cards, but will not be able to use the custom driver.

Using the native, both will work. Disadvantages being all that are expected with using native driver (a reduced throughput, more CPU usage, etc.).

The performace difference between the drviers has decreased over the years so if you are not planning on melting the wire, then I guess native would work.

But I would try the custom first 🙂

I always try and melt the wire ;), but agreed that unless you are trying to punish the upper bounds of the 20Gbps limit of the large AMD and are passing moderate amounts of traffic, it should work properly.