ISP with two external IP Ranges

Hello,

hope anyone can help me with my request.

In our environment we have an ISP provider. The ISP provides us with two external IP networks. We currently have 2 vDoms set up. 1x for the first network, and 1x for the second network. We currently have only a default route to the first network created 0.0.0.0/0.0.0.0 to gateway 1. The problem that we have is on which way we can route also the traffic to the second gateway. What options do I have the right to use the second gateway.

thanks for your help

regards