Broken Proxmox VLAN aware?

catha1201

Member
Mar 12, 2021
9
2
6
I have spent days trying to find a solution to my problem - and would like to share my knowledge with you, as I do not hope that others run into the same problem.

I have a special advanced VLAN setup, as my ISP delivers an IP trunk with VLAN to me, which is delivered on the same physical switch1 as other servers. (bad combo, I know) I divide ports into VLANs so that ISP1 enters port 1/VLAN100, - and ISP2 enters port2/VLAN101 - and from there a trunk to physical switch2, where Proxmox server1 is located.

Inside proxmox there is a network card with vmbr0 with vlan aware. On proxmox1 there is a Pfsense firewall which is my router/L3 with all VLANs located (users vlans 2,3,4,5 - and ISP vlan 100 and vlan 101)

No problems so far... all interfaces on IPv4 are up, all traffic routes fine between vlans and public internet. VMs and physical PCs run fine without problems on IPv4. Everyone gets an assigned IPv4 address from the pfsense dhcpv4 server. Everyone is happy.

Since my ISPs have a Native IPv6 network with Carrier Grade NAT, I thought I would add IPv6 and run Dual IP so I could take advantage of IPv6.

Pfsense setup is simple enough and all interfaces receive a /64 (my ISP provides a /48) and everything seems to work - right up until I have to use DHCPv6 and Router Advertisements.

No clients - neither VMs nor physical PCs receive IPv6 addresses from the DHCPv6 server, and no routes are established. After an extended period of a few hours, the PC/VMs receives SLAAC addresses, but no routes.

I'm a big question mark, and start looking through my VLAN table to see if I've made a mistake, but no, it doesn't seem that way, so I jump into proxmox and create Linux VLANs for all VLANs. No result.

Several reboots of proxmox servers, switches and firewall later - same result. No IPv6 addresses via DHCPv6, but strangely SLAAC. No PC/VM will not route on IPv6 either. All PC/VMs work flawlessly on IPv4.

I throw up a new pfsense as physical machine and gone is the problem with exactly the same configuration.

The problem must be in proxmox networking, and so I use every conceivable option to get it to work on IPv6, but find that Open vSwitch has none of these problems. I move all configuration to Open vSwitch with VLANs - and gone is the problem! :)

All VMs/PCs receive IPv6 addresses from DHCPv6 server with RA.

Does this mean that Proxmox/Linux vlan aware is broken regarding IPv6?

Is there anyone who can poke holes in my "broken vlan aware" theory for me?

BTW; i can reproduce this situation in test server, test switch etc every time
 
I am having this exact same issue here. It's beyond me, how I can fix this. I'm seriously considering switching to ESXi, I just got my IPv6 prefix and I cannot for the life of me figure out how I can fix this. Truly infuriating.
 
I am having this exact same issue here. It's beyond me, how I can fix this. I'm seriously considering switching to ESXi, I just got my IPv6 prefix and I cannot for the life of me figure out how I can fix this. Truly infuriating.

Did you use OpenvSwitch? And which brand is your router/FW handing out the DHCPv6 addresses?
 
Did you use OpenvSwitch? And which brand is your router/FW handing out the DHCPv6 addresses?
I’ve literally just tried OVS. Right this moment, before receiving this. Unbelievably, it works. I can ping, dig, I’ve got full functionality, DHCPv6 and SLAAC. I swear, I’d almost given up on it. FYI, I’ve got a pfSense VM.

Now there’s the question of why Linux Bridges don’t work with IPv6 and tagged VLANs, but that’s beyond my technical ability to solve.
 
I’ve literally just tried OVS. Right this moment, before receiving this. Unbelievably, it works. I can ping, dig, I’ve got full functionality, DHCPv6 and SLAAC. I swear, I’d almost given up on it. FYI, I’ve got a pfSense VM.

Now there’s the question of why Linux Bridges don’t work with IPv6 and tagged VLANs, but that’s beyond my technical ability to solve.

Good for you, but in my case it works on and off, which is even more influriating. When the DHCPv6 lease runs out, it stops working again, until I restart the service.
 
Good for you, but in my case it works on and off, which is even more influriating. When the DHCPv6 lease runs out, it stops working again, until I restart the service.
Unfortunately, I don’t use DHCPv6 on my tagged VLAN interfaces, but on my untagged one it does work well.
 

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