Nic passthrough to truenas vm and mac address

juju01

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May 16, 2020
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I want to passthrough a dedicated 10G nic port to my truenas scale setup. I typically setup the static ip address by mapping a mac address to the static ip in my dhcp server. Not sure how this will work with the passthrough nic. I know the mac address of the NIC port. However, not sure where to assign it in truenas scale. I see I can assign a static ip directly in truenas, without specifying a mac address - but not sure my dhcp server will pick this up? Any pointers on how to do this will be appreciated.

ps: I know alternatively, I can just setup a new bridge and assign that to the vm. thats what I have done now. Is there a performance hit by going this route vs passing the nic through ?
 
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Not sure how this will work with the passthrough nic.

I have not verified it, but I would highly expect, that if you PCIe-passthrough the NIC to a VM, its corresponding real MAC-address is also in that VM on that specific NIC, because it is bound to the hardware/physical NIC?!

Or do you talk about SR-IOV?

Maybe I simply misunderstand something?

ps: I know alternatively, I can just setup a new bridge and assign that to the vm. thats what I have done now. Is there a performance hit by going this route vs passing the nic through ?

Do you actually see a performance hit? (With your 10 Gb NIC in mind.)

The performance of a Linux bridge normally depends on the CPU-performance of the host.
So, if you do not have a potato-CPU, you should get at least 20 Gb/s.

An advantage with staying with the Linux bridge for the TrueNAS-VM would be, that traffic from/to other guests that are on that same bridge, does not need to leave the physical network interface and is therefore not restricted to the, in your case, 10 Gb/s from the physical NIC; of course, depending on your host-CPU.

Would recommend to simply measure it for your specific environment (to and from the different clients and servers) with e.g.: iperf3.