How to add Default Gateway not on the same network?


#1

Hello,

I’m using a Peplink Balance One. I just tried to configure a Static IP WAN with a Default Gateway not within the same network. This is useful with some WAN devices that take LAN addresses (example 192.168.100.1) but act as a IP bridge, letting the other endpoint (in this case the Peplink) to take a public IP address with subnet mask /32. The user interface is warning me about the configuration but is letting me doing it. How do I continue now? If I could, I would right away add a static route for the single IP address 192.168.100.1 on the specified WAN interface, but I the interface won’t allow to add such static route. I tried adding an Enforced Outgoing Policy like this:

Source: Any
Destination: IP Address 192.168.100.1
Protocol: Any
Algorithm: Enforced
Enforced Connection: -> The WAN interface connected to the “bridge” device

But it didn’t work either. How I make it work? Is this use case supported at all?


#2

@ceztko

Would you able to provide a hand drawing diagram explaining your setup ?


#3

Yes. I would also like to correct my previous post: my current setup is a WAN gateway with a data link bridge between the ppp interface and its eth0 interface. The gateway is configurable so the ppp interface wan’t take the ip address. The diagram follows:

What I initially described is a WAN gateway with an IP bridge that similarly won’t take public address on the ppp interface. This solution was sometimes used years ago by so called “soft bridge” modems and they were easy to configure since they provided the correct route to the gateway LAN address trough DHCP. I don’t use these modems anymore but the concept was similar and it was easier to explain. Diagrams follow also for this setup:

Both gateways, with data-link or IP bridge, needs a route to reach the 192.168.100.1, which is in a unknown network. This could be configured as a static route on the single IP address trough the WAN1 device (which I don’t think it can be done with the Peplink user interface), or WAN1 could take another non primary LAN IP address, but as far as I know also the latter is also not possible as Peplink can configure only public /32 additional IP addresses.


#4

Sorry if i get you wrong …

Are you looking the Management IP for you IP Bridge ?

Do you think the Management IP option for PPPoE WAN will help for your case ?


#5

Unfortunately this assumes I’m initiating a pppoe connection on my peplink, which sadly is not my scenario. The WAN1 gateway is initiating a pppoe connection on a ONT (Optical Network Terminal) which was configured by the ISP and sadly I was not able to mimic on the peplink (when I tried it, I got “no pppoe service detected” on the Peplink). On the Peplink I have a Static IP configured, set with primary IP address a LAN address which is being NAT-ted trough the gateway, which is currently taking the public address on its ppp interface. The public IP address is then configured as additional public IP address in the Peplink. This seems exotic, but kind of works since on the WAN1 gateway a data link bridge is configured so everything coming from ppp will sink in the eth0 interface of the gateway and arrive to the Peplink. This is suboptimal as the primary IP address of the Peplink is not a public ip address, outbound packets are being NAT-ed and and I’m seeing compatibility problems. As said previously, I can disable NAT and I can tell the ppp interface to not take the public IP address and so I can have Peplink reserve it: the missing link would then have a way to tell Peplink with a Static IP WAN configuration how to reach a gateway which is not in the same network, which is the main question asked here. “Management IP address” would work but it’s only available for the pppoe configurations. What would help here could be:

  1. the ability to add arbitrary additional IP addresses in the Peplink WAN interface when using Static IP configuration, not limiting it to public /32 addresses;
  2. the ability to add a static route that will tell Peplink how to reach the a single IP address on the specific WAN interface;
  3. I could add VLAN interface with IP address in the same LAN network of the WAN gateway, assign it to a LAN port in the Peplink and connect a second link to the WAN gateway. It seems exotic and dirty. I didn’t try it but it could work…
  4. Any other suggestion it come up in your mind that may help here.

Honestly, I would expect Peplink to support either 1) and/or 2), since they would be the cleaner solution and especially 1) would be very easy to implement on Peplink side, as it’s partially already implemented for pppoe connections, as you just suggested to me.