WAN load balancing with single Ethernet

I have setup multi wan connection with mwan3 packet and it's work with multiple Ethernet and wireless.
The problem, how can I use single eth cable to make dual wan. I have two modem connected on tha same switch as wan switch and it has different ip class for every modem.

What I'm this is my progress

  1. Activate wan with wan interface and seting up ip class modem A
  2. Activate load balancing with this interface
  3. Check ping status with and replayed from open wrt and connected device routed to wan
  4. Activate wanc with wan interface
  5. Setting up ip interface with ip class modem C
  6. Activate load balancing with wanc
  7. successfully ping from open wrt with ping -i wanc
  8. The problem, device connected routed to wanc cannot ping ip class modem c and

Any advice?

Note: wanb usually used with lan port to modem at now disabled.

You need a smart/managed switch so that you can assign each WAN to a VLAN. Then you'll setup trunk ports on both the switch and the OpenWrt router in order to allow multiple VLANs to exist on a single cable.

Oo, so this is not possible to do with ip subneting with multiple IP gateway

It is plausible that it could work in the right circumstances (for example, no DHCP server, no PPPoE, simply static IP addresses), but I honestly don't think it would work (or work properly). Regardless, doing this without VLANs is the wrong way to go about it. Anytime you are putting multiple networks on the same cable, it should be done with VLANs.

It's not.

You somehow need to get two different two modems working over a single cable (here a switch becomes a necessity), and for that to really work, you need to configure each of them for a different VLAN (and at this point it needs to be a (L2-) managed switch, instead of an unmanaged one). Modem and router aren't using IP to talk to each other, so their subnetting doesn't even matter (apart from access to the modem's management interface, which is optional).

Yes I just need static IP to work.

Vlan switch is not option at right now.
The modem switch used to connect two modem from different location. I do decentralized load balancing device from every location

It's either a VLAN capable switch - or two cables all the way between modem(s) and router.

The modem is Nat . And this is work fine when we are setting up with two different wifi router(as AP an nat) conecting on switch with each one connected to gateway modem .
So isi it possible to do with one open wrt device


You need different VLANs for each modem, and some way to get two ethernet devices share one cable, hence L2 managed switch (3 ports needed). Or two independent cable runs between modems and OpenWrt router.

It is not advisable to run multiple subnets on a single wire .
But it does work . I have ran multiple subnets on unmanaged switches.

Brodcasts do get transmited to everyone, but only those listening on specific
subnets will accept and respond.

In other words your two modems can be on two different subnets internaly, connected
to an unmanaged switch, and openwrt can be connected to same switch
with single wire from wan port, and wan port can have two layer3 interfaces in different subnets
with a gateway pointing to respective cable modem.

But vlan solution is more reasonable, if you have a managed switch.

If someone knows of actual conflicts , please speak up.

yes it shouldo , but my open wrt didnt work, only 1 WAN can conected in the same switch,

Configure OpenWrt interfaces statically using different subnets.