Proxmox SDN (Software-Defined Networking) defines networks once at datacenter level and pushes them to every node. Instead of editing bridges by hand on each server, you create zones and VNets in the web UI and VMs simply attach to them.
Before you start
- Proxmox VE 8.1 or newer, where SDN is included by default (
pveversion). - The
source /etc/network/interfaces.d/*line present at the end of/etc/network/interfaceson each node, which SDN needs. - For DHCP in simple zones: the
dnsmasqpackage installed on every node.
Key Proxmox SDN terms
| Term | Meaning |
|---|---|
| Zone | The type of network separation: Simple, VLAN, QinQ, VXLAN or EVPN |
| VNet | A virtual network inside a zone; appears to VMs like a bridge |
| Subnet | An IP range on a VNet, with gateway, optional SNAT and DHCP range |
Create a simple zone with NAT
- Datacenter → SDN → Zones → Add → Simple. Give it an ID such as
lab, tick automatic DHCP if you want it, and save. - SDN → VNets → Create: name it (for example
labnet) and pick the zone. - Select the VNet and add a Subnet:
10.20.0.0/24, gateway10.20.0.1, tick SNAT for internet access, and add a DHCP range if enabled. - Go to Datacenter → SDN and click Apply.
- Attach a VM's network device to bridge
labnet.
A simple zone is local to each node; VMs on different nodes are not connected by it.
VLAN and VXLAN zones
- VLAN zone: choose an existing VLAN-aware bridge (such as
vmbr0), then create VNets with a tag. The switch must carry those VLANs. - VXLAN zone: enter the node IPs as peers; VNets get a VXLAN ID and span all nodes over your existing network. Lower the VM MTU (commonly to 1450) to fit the VXLAN overhead.
Note: Nothing changes on the nodes until you click Apply. Review pending changes first.
Troubleshooting
- VNet not shown on a node: the
interfaces.dsource line is missing or Apply failed on that node; check its task log. - No DHCP leases: install
dnsmasqand check the subnet's DHCP range. - VXLAN traffic drops large packets: MTU too high inside VMs.
Frequently asked questions
Do I have to use SDN?
No. Classic bridges still work (bridges and VLANs); SDN is helpful for clusters.
Can the firewall work with SDN VNets?
Yes, VM firewall rules still apply on their network devices.
Which zone type should I start with?
Simple for single-node labs, VLAN if your switches already use VLANs, VXLAN to stretch networks over routed links.