amel

I agree with the suggestion from Edwin that trying to combine links with such different performance characteristics and latency can be problematic. One suggestion would be to configure a default route pointing at the higher capacity link and configure a floating static default route pointing at the lower capacity link.

But you asked how to share the links and the question deserves an answer. The easy way to do it is to configure two static default routes with one pointing to the high capacity link and one pointing to the lower capacity link.

I like the suggestion from Mike about using Policy Based Routing in a situation like this. And I have done that at a customer site that had a high capacity link and a lower capacity link. We configured it so that the high capacity link was the usual default outbound link for traffic and the lower capacity link was a backup link to use if the primary failed. We then configured PBR to identify traffic from certain source addresses and send them over the lower capacity link. It works quite well.

Let me point out that in doing this, PBR will take care of your outbound traffic. You would need to arrange something to get the return traffic on the proper link.

HTH

Rick