Multiple management IPs on 2 NICs

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doxymoron

New Member
Apr 1, 2024
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I was trying to add a second management IP to another NIC in proxmox, but when I created it, it does not seem to be attached to the new NIC. For example this is what I setup:

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To me it seems simple, each NIC has it's own IP. But both IPs are attached to vmbr0/eno8403. If I unplug that NIC, both IPs stop working. Am I looking at something wrong? Thanks.
 
In general, it is not recommended to have several interfaces using the same subnet, as this can cause routing problems.

What is the use case, is it really necessary?

Also, if you do an ip addr and an ip r before/after disconnecting the NIC, what do you see?
 
ZyX said:
In general, it is not recommended to have several interfaces using the same subnet, as this can cause routing problems.

What is the use case, is it really necessary?

Also, if you do an ip addr and an ip r before/after disconnecting the NIC, what do you see?
Click to expand...
I really wasn't trying to do this permanently, I only had remote access, and I was simply trying to create a second IP on another NIC. Then access via the new IP, and remove the old one. When I disconnect the cable connected to eno8403, vmbr0 link shows down. But vmbr1 link still shows up...but is not pingable/accessible.
 
Is there a router between the proxmox and your computer? Are you on a different network ? Is the default gateway on vmbr0?

If so, and the eno8403 interface is disconnected, then your proxmox no longer has a default gateway, you need to remove the default gateway from vmbr0 and put it on vmbr1.
 
Last edited:
doxymoron said:
No router, just a switch. Currently there is no default gateway set in proxmox.
Click to expand...
After removing the NIC, can you try clearing the arp table with ip -s -s neigh flush all and then try contacting the proxmox again?

Also, have you tried doing a tcpdump to see if the packets actually reach the proxmox after removing the NIC? And if they do, does the proxmox try to respond and if so via which interface?
 
There is still no connectivity after removing NIC and running that command. I have not gone that far with it yet, I was just looking to see if I had configured something incorrectly.
 
But I was trying to use multiple IPs on different interfaces, and it was creating it on the same interface.
 
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