Configure multiple subnets and metrics

[Gistek I. S.]

Hi,
I want to configure the network for my proxmox server.
The server has 6 interfaces (2 at 10Gbps and 4 at 1Gbps).
I want to use one 10Gbps and one 1Gbps interface to connect the server to the LAN (by a switch) and two 1Gbps interfaces to connect the server directy to the firewall with diferentes subnets to have some VM's connected directly to the firewall out of the LAN

I also want the server to use the interfaces in this order for the external traffic:

1. First the 10Gbps interface connected to the LAN (also the first for the LAN traffic)
2. Second the 1Gbps interface connected to the LAN (also the second for the LAN traffic)
3. Third one of the 1Gbps interface connected directly to the firewall (only used for the external traffic)
4. Fourth the other 1Gbps interface connected directly to the firewall(only used for the external traffic)

With this configuration what I want to achieve is having two networks in each VM; one for the LAN and the other for the external traffic, to divide the external and internal traffic.

Adittional info:

• LAN subnet: 10.115.100.X
• Firewall ip in LAN subnet: 10.115.100.100
• Firewall external subnet 1: 10.115.102.X
• Firewall ip in external subnet 1: 10.115.102.100
  
• Firewall external subnet 2: 10.115.103.X
  
• Firewall ip in external subnet 2: 10.115.103.100

The "/etc/network/interfaces" looks like this:

auto lo
iface lo inet loopback

iface enp35s0f0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 10.115.100.1
        netmask 255.255.255.0
        gateway 10.115.100.100
        bridge_ports enp35s0f0
        bridge_stp off
        bridge_fd 0
#Switch office 1

iface eno1 inet manual

auto vmbr1
iface vmbr1 inet static
        address 10.115.100.2
        netmask 255.255.255.0
        gateway 10.115.100.100
        bridge_ports eno1
        bridge_stp off
        bridge_fd 0
#Switch office 2

iface eno2 inet manual

auto vmbr2
iface vmbr2 inet static
        address 10.115.102.155
        netmask 255.255.255.0
        gateway 10.115.102.100
        bridge_ports eno2
        bridge_stp off
        bridge_fd 0
#Firewall office 1

iface eno3 inet manual

auto vmbr3
iface vmbr3 inet static
        address  10.115.103.155
        netmask  255.255.255.0
        gateway  10.115.103.100
        bridge_ports eno3
        bridge_stp off
        bridge_fd 0
#Firewall office 2

iface eno4 inet manual

iface enp35s0f1 inet manual

How can this be done???