config issue with multiple VLAN and cisco device

S

sandeep_kr05

New Member
Oct 8, 2025
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Current Setup Overview


  • Servers:
    3-node cluster, each with 2 NICs configured in a bond setup (LACP).
  • Switch:
    Cisco 3750 Layer 3 switch.
  • VLAN Configuration (Multiple VLANs):
    1. Management / Proxmox Bare Metal
      • VLAN ID: 110
      • Subnet: 10.89.4.0/24
      • Gateway: 10.89.20.3
    2. VM Network 1
      • VLAN ID: 20
      • Subnet: 10.20.30.0/24
      • Gateway: 10.20.30.3
    3. VM Network 2
      • VLAN ID: 30
      • Subnet: 192.168.1.0/24
      • Gateway: 192.168.1.3

Requirement / Issue:


I have a multi-VLAN setup for different network segments, and the Cisco switch ports connected to Proxmox nodes are already configured as trunk ports.


I want all VMs across different VLANs to be accessible from outside (via routing or NAT as needed), based on the existing trunk configuration.

Config proxmox server :
auto lo
iface lo inet loopback

auto eno1
iface eno1 inet manual

auto eno2
iface eno2 inet manual

iface eno3 inet manual

iface eno4 inet manual

auto bond0
iface bond0 inet manual
bond-slaves eno1 eno2
bond-miimon 100
bond-mode active-backup
bond-primary eno1

auto vmbr0
iface vmbr0 inet static
address 10.89.20.51/24
gateway 10.89.20.3
bridge-ports bond0
bridge-stp off
bridge-fd 0
bridge-vlan-aware yes
bridge-vids 2-4094

auto vmbr0.110
iface vmbr0.110 inet manual

source /etc/network/interfaces.d/*
root@proxmox2:~#

Config Cisco Switch :

interface GigabitEthernet0/23
switchport trunk allowed vlan 105,120,130,160,170
switchport trunk encapsulation dot1q
switchport mode trunk
!


Looking for guidance or best practices on how to properly configure this in Proxmox (e.g., /etc/network/interfaces, Linux bridges, VLAN awareness, etc.).
 
readyspace said:
Hi, have you started your configuration in Proxmox VE nodes? If so, can you share the config in there?
Click to expand...
Config proxmox server :
auto lo
iface lo inet loopback

auto eno1
iface eno1 inet manual

auto eno2
iface eno2 inet manual

iface eno3 inet manual

iface eno4 inet manual

auto bond0
iface bond0 inet manual
bond-slaves eno1 eno2
bond-miimon 100
bond-mode active-backup
bond-primary eno1

auto vmbr0
iface vmbr0 inet static
address 10.89.20.51/24
gateway 10.89.20.3
bridge-ports bond0
bridge-stp off
bridge-fd 0
bridge-vlan-aware yes
bridge-vids 2-4094

auto vmbr0.110
iface vmbr0.110 inet manual

source /etc/network/interfaces.d/*
root@proxmox2:~#
 
Thanks for sharing your config — you’re almost there.

A few quick points:
  1. Keep only one bridge (vmbr0) — you already made it VLAN-aware, so no need to create vmbr0.110 unless the Proxmox host itself needs an IP inside that VLAN.
  2. For your VMs:
    • Use bridge vmbr0
    • Set the VLAN tag (e.g. 20 or 30) in the VM’s hardware network settings.
    • That’s all you need for multi-VLAN setup.
  3. Bond mode:
    • Your Proxmox uses active-backup, but your switch looks like it expects LACP (802.3ad).
    • Either change Proxmox bond mode to 802.3ad, or disable LACP on the switch and keep active-backup.
    • They must match.
  4. Routing:
    • Let your Cisco 3750 handle inter-VLAN routing and gateways — keep Proxmox at Layer 2 only.
After that, VMs in different VLANs should reach their gateways and work normally.
 
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