Multiple ISP connections to the same WAN interface

Routing & Switching
1

Hi Rene,

I would like to understand that if I have only 1 WAN interface and if I want to connect 2 ISP links to the same interface - How can I achieve it?

3

Maybe something similar to router on a stick.

4

Hello Amit

If you have a single physical WAN interface, there is no way to connect two ISPs to that directly. You have the very basic problem of each ISP delivering a physical cable to your premises, and you have only a single interface. You simply can’t connect both cables to the same interface.

If you want to achieve something like this, you will need an intermediary device between your WAN interface and the two ISP circuits. This would most often be a router but may also be a switch or firewall depending upon the topology you choose, and the types of connections to the ISP.

If you want to find out more about edge network topologies, take a look at these related lessons:

I hope this has been helpful!

Laz

5

If I use a L2 switch between the 2 ISPs and my router - Can I create sub-interfaces to achieve this?

6

Hello Amit

Yes, that would be a solution. You can create two VLANs on the L2 switch and configure a router on a stick. That way, the router will have two subinterfaces on the physical interface, each one connected to one of the ISPs. You can then decide how to distribute connectivity to the ISPs from your router. For more info on configuring router on a stick, take a look at the following lesson:

In your scenario, you can consider the two hosts as the two ISP routers.

I hope this has been helpful!

Laz

1 Like
7

Thanks Laz for the clarification

1 Like