Can't configure bridge for VMs to see NAS: "The network 192.168.0.0/24 is already in use by another interface."

[plastic1982]

LT Nominating Commn re Sean Thomson
I am trying out Truenas SCALE, running 22.02.1. My server specs are as follows:

MB: Supermicro M11SDV-8CT-LN4F

Proc: AMD EPYC 3201 SoC

16GB Supermicro SATA DOM

6 x 8TB WD Red

4x 1GbE with Intel I350-AM4

I have set up the NAS aspect of the system and it works perfectly on my local network. I have set up a Windows 10 VM and an Ubuntu 22.04 VM, which both work, and have WAN access. My issue is that I cannot access the NAS storage from the VMs.

I have tried to set up a bridge interface so that my VM can see the NAS, using the below reference guide, but I am stuck because my networking settings keep giving me the same error no matter what I do.

https://www.truenas.com/docs/scale/scaleuireference/virtualization/accessingnasfromvm/

My motherboard has an IPMI NIC, and 4 Intel gigabit NICs called “eno1” through “eno4”

Eno1 presently has DHCP active, and has an assigned IP4 of 192.168.0.148/24

Eno2 presently has an IP alias of 192.168.0.140/24

Eno 3 and 4 are not active

I am trying to set up a bridge so my VMs can see my NAS, but if I uncheck DHCP on eno1, and try to set the IP4 as 192.168.0.148/24, it gives the error “The network 192.168.0.0/24 is already in use by another interface.”

If I try to set up a bridge and try to set the IP4 as 192.168.0.140/24, it gives the error “The network 192.168.0.0/24 is already in use by another interface.”

Basically, no matter what I try, I cannot set an IP alias. I don’t really know how it let me set the one for eno2. If I can’t see the NAS from my VMs, my use case is severely hampered. Can someone tell me how to solve this “The network 192.168.0.0/24 is already in use by another interface.” Issue so I can get my bridge working?

 

[neofusion]

I don't think you can do this.

Something similar has been discussed in many places of the forum. Here is one example:

Questions pertaining to network interfaces and their validation errors

About 2-3 weeks ago, I stopped being able to access the NAS drive on my network. Pinging the IP addresses of the ethernet ports returned 100% packet loss. I spent a great deal of time troubleshooting, including swapping wires, resetting router settings, etc. Unable to diagnose the problem, I...

www.truenas.com

By the way, double check the first line of your post, looks like something else snuck in there, probably inadvertently.

 

[morganL]

Eno1 presently has DHCP active, and has an assigned IP4 of 192.168.0.148/24

Eno2 presently has an IP alias of 192.168.0.140/24

Eno 3 and 4 are not active

I am trying to set up a bridge so my VMs can see my NAS, but if I uncheck DHCP on eno1, and try to set the IP4 as 192.168.0.148/24, it gives the error “The network 192.168.0.0/24 is already in use by another interface.”

If I try to set up a bridge and try to set the IP4 as 192.168.0.140/24, it gives the error “The network 192.168.0.0/24 is already in use by another interface.”

Basically, no matter what I try, I cannot set an IP alias. I don’t really know how it let me set the one for eno2. If I can’t see the NAS from my VMs, my use case is severely hampered. Can someone tell me how to solve this “The network 192.168.0.0/24 is already in use by another interface.” Issue so I can get my bridge working?

The OS doesn't really support having multiple IP addresses on the same subnet.

Resource - Multiple network interfaces on a single subnet

We've had a number of people over the years bring up the topic of multiple network interfaces on a single subnet. Often done by Windows administrators or storage admins, where it works to varying degrees, this is sadly not proper IP networking...

www.truenas.com

 

[plastic1982]

Thank you both for pointing out some resources. It's clear that I can't have two NICs running on the same subnet, but I guess the solution is still not clear to me. My goal was to have one NIC dedicated to the NAS, and the other dedicated to the VMs. It seems that my possible solutions are:

1. Link Aggregation to increase bandwidth and have both sides of the system run over the single aggregated link.
2. Unplug one NIC and have both sides of the system run over a single link, presuming a single gigabit is good enough
3. Have the NICs run on different subnets.

I suppose option 3 is the best option to achieve my original goal of one NIC for each side of the system. I guess I am not well versed enough in networking to know how to do this. Can anyone point me to resources on how to properly set up networking?

 

[Patrick M. Hausen]

If you want one NIC for the NAS and one for the VMs then

• assign the IP address to the NIC for the NAS
• create br0 interface with the other interface as the member for the VMs
• don't assign an IP address to that second interface or the bridge
• connect both interfaces to the same switch (or VLAN if you have that)

The bridge is just a layer 2 connection like a vSwitch in VMware. No layer 3 address needed. Each VM comes with its own address in the same subnet. I am not familiar enough with SCALE to know if you need anything special for the second interface to be "active" without an IP address assigned. In CORE you would put "up" into the options field.

 

[plastic1982]

I have this working now, but I seem to have broken my applications now. (?) Thanks for all your help